|
I have an HP 16500C logic analyser. Actual unit tests fine in the diagnostics but unfortunately the two 16557D cards in it have suffered the green death and fail diagnostics. Does anyone have any of these cards for sale that test good? Or what might be some alternate cards to them that don't have the same problem for sale? It is a real shame as the rest of the unit is in excellent condition and I need it for some hobby work I am doing. I asked around in test instrument group but seems more logical for me to ask here. I've removed the plastic sliders and the glue. Fixed some bad tracks. Boards may have problems with the vias. At point to go further I think I would need schematics or just to buy some working/tested boards. Suggestions for alternate boards that do not have this problem??
--
|
Hi Damien,
There are no schematics available that I've ever seen.? And I don't know of any analysis cards that don't have this problem to some extent.? All the analysis cards I've seen have components on the bottom, and therefore the plastic runners to "protect" them from getting raked off.
You don't say what country you're in, but right now on ebay there are two 16557D cards for sale in the USA for USD$49.95 each (+ shipping) in "Used" condition, which means they are claimed as working by the seller.? If you get them and they don't work, you can return them as "Not as Described", whether the seller accepts returns or not.? For the ones I see (item #305031279984), the seller accepts returns anyway.
That's inexpensive for these cards, and a factor may be that they don't have cables, but presumably you don't need those anyway.? What do you have to lose.
You could also try buying one, and if it works use it as a comparison to fix yours.? It's much easier to fix these corroded cards if you can compare to a working one.
Another tack is if you know someone with a 16700 mainframe, you can plug in your 16557D cards and turn on some fairly verbose debugging during self-test which may lead you to the problem.? I'm not familiar enough with the 16500C to know if it has something similar.? Maybe someone else can comment on its debugging capabilities.
-mark
|
Thanks. I did find an article on fixing these boards buti it was a slightly different revision of the board. I've ordered up a decent scope so I can see the tracks better. I wonder if anyone can give me some details about the vias. The problems I have identified appear not to be with the hollow via type pins that go all the way through ( which have some sort of protective coating on them ) but with the kind that appear to join pads together. From the article I read they apparently have solder in them that can be sucked out but the ones on this board seem like they are solid. Anybody that has any insight in to doing this repair I would be interested to hear from.?
On Thu, Nov 16, 2023 at 5:57?AM Mark Litwack < mlitwack@...> wrote: Hi Damien,
There are no schematics available that I've ever seen.? And I don't know of any analysis cards that don't have this problem to some extent.? All the analysis cards I've seen have components on the bottom, and therefore the plastic runners to "protect" them from getting raked off.
You don't say what country you're in, but right now on ebay there are two 16557D cards for sale in the USA for USD$49.95 each (+ shipping) in "Used" condition, which means they are claimed as working by the seller.? If you get them and they don't work, you can return them as "Not as Described", whether the seller accepts returns or not.? For the ones I see (item #305031279984), the seller accepts returns anyway.
That's inexpensive for these cards, and a factor may be that they don't have cables, but presumably you don't need those anyway.? What do you have to lose.
You could also try buying one, and if it works use it as a comparison to fix yours.? It's much easier to fix these corroded cards if you can compare to a working one.
Another tack is if you know someone with a 16700 mainframe, you can plug in your 16557D cards and turn on some fairly verbose debugging during self-test which may lead you to the problem.? I'm not familiar enough with the 16500C to know if it has something similar.? Maybe someone else can comment on its debugging capabilities.
-mark
|
I recently repaired a handful of 16752 boards that are now in my 16903 mainframe. I repaired 4 out of the 5 boards I have, and just haven't gotten time to find the one last remaining broken track on the last one (and my mainframe only has 3 slots anyway, so I already have one extra working card than I have slots)
The issue I saw the most was corrosion right where the track goes to the opening in the solder mask for the pads / pins - especially on the resistor packs that are EVERYWHERE on the card. Even under a microscope, they're hard to tell there's an issue there.
If you look at the 2nd and 3rd pictures in that album - the little green blobs of corrosion right at the solder mask openings is what I'm talking about. You can see later where I scraped the blobs away, and the traces are completely open there and the pads are not connected at all.
On the worst card, I ended up removing nearly all of the 330 ohm resistor packs and inspecting carefully, fixing tracks, and putting all the resistor packs back.
The same is true for any traces that have "testpoints" in the middle of them, like can be seen on the left side of the 2nd and 3rd picture sin that album - there's an opening in the solder mask for the test points, and there can be corrosion there too. And if you reflow those test points, the solder itself is kindof powdery looking, and when you heat it some lumpy brown stuff comes out - I tried to reflow as many of those as possible that didn't look nice and shiny, and sometimes scrapped a little solder mask back on the edges and made sure the solder was making good contact to known good copper in the traces on both sides of the test points.
I'm not sure how similar the 165xx cards are to these 167xx cards.
In general, you won't find ANY of these cards that don't have some issues - even if you buy cards off of ebay that work now, they might be right on the edge of failing. I definitely did get some steep discounts for buying cards that were "used" (aka should be working) but turned out to be not working and failing the self tests.?
The self test with the detailed failure report in the 16700 / 16900 is invaluable for fixing these boards. If the 16500 mainframe has that too, that will definitely help.
My one word of caution is if you're testing 167xx cards in a 169xx mainframe, the chip identifiers (U53 etc) DOES NOT MATCH THE BOARDS. I had to inject some of my own faults to figure out the mapping between what the self test was saying and which chip on the board it was actually talking about (the purple wire wrap wire in some of those pictures). I think that's because the 167xx cards that are supported in the 169xx mainframe have equivalent 169xx cards that are similar, but not exactly the same. I'm guessing from the software side, they use the same drivers / same self test, but when they laid out the PCB for the newer 169xx variants of the cards, the chip identifiers were changed, and the self test is only accurate for the newer 169xx equivalent cards.
I also bought a new microscope on a boom arm mount to be able to deal with these cards - it was very useful as well - the boards were too big to be able to get to all of it under my old microscope, which has a pedestal stand.
Thanks. I did find an article on fixing these boards buti it was a slightly different revision of the board. I've ordered up a decent scope so I can see the tracks better. I wonder if anyone can give me some details about the vias. The problems I have identified appear not to be with the hollow via type pins that go all the way through ( which have some sort of protective coating on them ) but with the kind that appear to join pads together. From the article I read they apparently have solder in them that can be sucked out but the ones on this board seem like they are solid. Anybody that has any insight in to doing this repair I would be interested to hear from.?
On Thu, Nov 16, 2023 at 5:57?AM Mark Litwack < mlitwack@...> wrote: Hi Damien,
There are no schematics available that I've ever seen.? And I don't know of any analysis cards that don't have this problem to some extent.? All the analysis cards I've seen have components on the bottom, and therefore the plastic runners to "protect" them from getting raked off.
You don't say what country you're in, but right now on ebay there are two 16557D cards for sale in the USA for USD$49.95 each (+ shipping) in "Used" condition, which means they are claimed as working by the seller.? If you get them and they don't work, you can return them as "Not as Described", whether the seller accepts returns or not.? For the ones I see (item #305031279984), the seller accepts returns anyway.
That's inexpensive for these cards, and a factor may be that they don't have cables, but presumably you don't need those anyway.? What do you have to lose.
You could also try buying one, and if it works use it as a comparison to fix yours.? It's much easier to fix these corroded cards if you can compare to a working one.
Another tack is if you know someone with a 16700 mainframe, you can plug in your 16557D cards and turn on some fairly verbose debugging during self-test which may lead you to the problem.? I'm not familiar enough with the 16500C to know if it has something similar.? Maybe someone else can comment on its debugging capabilities.
-mark
--
|
Looking at this from the point of view of making PC boards:
Corrosion on the surface kills one track.? That can be cured several ways and rather easily.
If corrosion covers a via, or a lead for a part, then life can be more complicated.
The board manufacturing process makes what's effectively an eyelet between the top and bottom layers.? The inner layers have their own eyelet (effectively).? When the board is assembled, the plating through process connects all these layers with the hole plating.
Corrosion can break this bond between layers.? To fix this, you must know where the inner layers (if any) connect.? That can be a problem unless you have a working board (and can trace it) or a schematic.
Harvey
toggle quoted message
Show quoted text
On 11/16/2023 5:53 PM, Damien Towning wrote: Thanks. I did find an article on fixing these boards buti it was a slightly different revision of the board. I've ordered up a decent scope so I can see the tracks better. I wonder if anyone can give me some details about the vias. The problems I have identified appear not to be with the hollow via type pins that go all the way through ( which have some sort of protective coating on them ) but with the kind that appear to join pads together. From the article I read they apparently have solder in them that can be sucked out but the ones on this board seem like they are solid. Anybody that has any insight in to doing this repair I would be interested to hear from.
On Thu, Nov 16, 2023 at 5:57?AM Mark Litwack <mlitwack@...> wrote:
Hi Damien,
There are no schematics available that I've ever seen.? And I
don't know of any analysis cards that don't have this problem to
some extent.? All the analysis cards I've seen have components on
the bottom, and therefore the plastic runners to "protect" them
from getting raked off.
You don't say what country you're in, but right now on ebay there
are two 16557D cards for sale in the USA for USD$49.95 each (+
shipping) in "Used" condition, which means they are claimed as
working by the seller.? If you get them and they don't work, you
can return them as "Not as Described", whether the seller accepts
returns or not.? For the ones I see (item #305031279984), the
seller accepts returns anyway.
That's inexpensive for these cards, and a factor may be that they
don't have cables, but presumably you don't need those anyway.?
What do you have to lose.
You could also try buying one, and if it works use it as a
comparison to fix yours.? It's much easier to fix these corroded
cards if you can compare to a working one.
Another tack is if you know someone with a 16700 mainframe, you
can plug in your 16557D cards and turn on some fairly verbose
debugging during self-test which may lead you to the problem.? I'm
not familiar enough with the 16500C to know if it has something
similar.? Maybe someone else can comment on its debugging
capabilities.
-mark
--
Damien Towning
|
Thanks for that. That is really helpful. When I looked at the issue as documented here :? I see that my board is a different revision. It is like they realised they had a problem and moved things around. So most of what is under the plastic runners is now visible tracks without via. Only a few seem to have got caught up in the green death. When the microscope turns up I think I will be able to take pictures with it and put them up somewhere. That comment about the resistor packs is a good pointer because at one of one of these rails is indeed a resistor pack. It looked clean but maybe it isn't. I am thinking about getting a solder sucking gun to pull the solder out of any bad via etc. Since it sounds like I will be doing a lot of that!??
On Fri, Nov 17, 2023 at 11:48?AM Harvey White < madyn@...> wrote: Looking at this from the point of view of making PC boards:
Corrosion on the surface kills one track.? That can be cured several
ways and rather easily.
If corrosion covers a via, or a lead for a part, then life can be more
complicated.
The board manufacturing process makes what's effectively an eyelet
between the top and bottom layers.? The inner layers have their own
eyelet (effectively).? When the board is assembled, the plating through
process connects all these layers with the hole plating.
Corrosion can break this bond between layers.? To fix this, you must
know where the inner layers (if any) connect.? That can be a problem
unless you have a working board (and can trace it) or a schematic.
Harvey
On 11/16/2023 5:53 PM, Damien Towning wrote:
> Thanks. I did find an article on fixing these boards buti it was a
> slightly different revision of the board. I've ordered up a decent
> scope so I can see the tracks better. I wonder if anyone can give me
> some details about the vias. The problems I have identified appear not
> to be with the hollow via type pins that go all the way through (
> which have some sort of protective coating on them ) but with the kind
> that appear to join pads together. From the article I read they
> apparently have solder in them that can be sucked out but the ones on
> this board seem like they are solid. Anybody that has any insight in
> to doing this repair I would be interested to hear from.
>
> On Thu, Nov 16, 2023 at 5:57?AM Mark Litwack
> <mlitwack@...> wrote:
>
>? ? ?Hi Damien,
>
>? ? ?There are no schematics available that I've ever seen.? And I
>? ? ?don't know of any analysis cards that don't have this problem to
>? ? ?some extent.? All the analysis cards I've seen have components on
>? ? ?the bottom, and therefore the plastic runners to "protect" them
>? ? ?from getting raked off.
>
>? ? ?You don't say what country you're in, but right now on ebay there
>? ? ?are two 16557D cards for sale in the USA for USD$49.95 each (+
>? ? ?shipping) in "Used" condition, which means they are claimed as
>? ? ?working by the seller.? If you get them and they don't work, you
>? ? ?can return them as "Not as Described", whether the seller accepts
>? ? ?returns or not.? For the ones I see (item #305031279984), the
>? ? ?seller accepts returns anyway.
>
>? ? ?That's inexpensive for these cards, and a factor may be that they
>? ? ?don't have cables, but presumably you don't need those anyway.?
>? ? ?What do you have to lose.
>
>? ? ?You could also try buying one, and if it works use it as a
>? ? ?comparison to fix yours.? It's much easier to fix these corroded
>? ? ?cards if you can compare to a working one.
>
>? ? ?Another tack is if you know someone with a 16700 mainframe, you
>? ? ?can plug in your 16557D cards and turn on some fairly verbose
>? ? ?debugging during self-test which may lead you to the problem.? I'm
>? ? ?not familiar enough with the 16500C to know if it has something
>? ? ?similar.? Maybe someone else can comment on its debugging
>? ? ?capabilities.
>
>? ? ?-mark
>
>
>
> --
> Damien Towning
>
>
>
|
A solder sucking gun works good for through hole, but if your resistor packs are surface mount (like the ones on the 16752 boards are), get yourself a hot air tool if you don't already have one. You'll wonder how you did anything without it once you have one. Even one of the super cheapie 858D ones will get you a long way, but if you want to spend a little more to get a much nicer tool, I'd recommend a Quick 861DW or the roughly equivalent Atten ST-862D. For the relatively cheap price of those tools, they're really good quality.
The solder sucker gun and the hot air tool are really complimentary tools - each one is good at different things, but they can also work together. If you have through hole parts on huge ground planes without proper thermal vias, and the solder sucker gun just doesn't have enough heat to get things melting, pre-heat the whole area with the hot air, and then go in with the solder sucker to actually free the part.
Thanks for that. That is really helpful. When I looked at the issue as documented here :? I see that my board is a different revision. It is like they realised they had a problem and moved things around. So most of what is under the plastic runners is now visible tracks without via. Only a few seem to have got caught up in the green death. When the microscope turns up I think I will be able to take pictures with it and put them up somewhere. That comment about the resistor packs is a good pointer because at one of one of these rails is indeed a resistor pack. It looked clean but maybe it isn't. I am thinking about getting a solder sucking gun to pull the solder out of any bad via etc. Since it sounds like I will be doing a lot of that!??
On Fri, Nov 17, 2023 at 11:48?AM Harvey White < madyn@...> wrote: Looking at this from the point of view of making PC boards:
Corrosion on the surface kills one track.? That can be cured several
ways and rather easily.
If corrosion covers a via, or a lead for a part, then life can be more
complicated.
The board manufacturing process makes what's effectively an eyelet
between the top and bottom layers.? The inner layers have their own
eyelet (effectively).? When the board is assembled, the plating through
process connects all these layers with the hole plating.
Corrosion can break this bond between layers.? To fix this, you must
know where the inner layers (if any) connect.? That can be a problem
unless you have a working board (and can trace it) or a schematic.
Harvey
On 11/16/2023 5:53 PM, Damien Towning wrote:
> Thanks. I did find an article on fixing these boards buti it was a
> slightly different revision of the board. I've ordered up a decent
> scope so I can see the tracks better. I wonder if anyone can give me
> some details about the vias. The problems I have identified appear not
> to be with the hollow via type pins that go all the way through (
> which have some sort of protective coating on them ) but with the kind
> that appear to join pads together. From the article I read they
> apparently have solder in them that can be sucked out but the ones on
> this board seem like they are solid. Anybody that has any insight in
> to doing this repair I would be interested to hear from.
>
> On Thu, Nov 16, 2023 at 5:57?AM Mark Litwack
> <mlitwack@...> wrote:
>
>? ? ?Hi Damien,
>
>? ? ?There are no schematics available that I've ever seen.? And I
>? ? ?don't know of any analysis cards that don't have this problem to
>? ? ?some extent.? All the analysis cards I've seen have components on
>? ? ?the bottom, and therefore the plastic runners to "protect" them
>? ? ?from getting raked off.
>
>? ? ?You don't say what country you're in, but right now on ebay there
>? ? ?are two 16557D cards for sale in the USA for USD$49.95 each (+
>? ? ?shipping) in "Used" condition, which means they are claimed as
>? ? ?working by the seller.? If you get them and they don't work, you
>? ? ?can return them as "Not as Described", whether the seller accepts
>? ? ?returns or not.? For the ones I see (item #305031279984), the
>? ? ?seller accepts returns anyway.
>
>? ? ?That's inexpensive for these cards, and a factor may be that they
>? ? ?don't have cables, but presumably you don't need those anyway.?
>? ? ?What do you have to lose.
>
>? ? ?You could also try buying one, and if it works use it as a
>? ? ?comparison to fix yours.? It's much easier to fix these corroded
>? ? ?cards if you can compare to a working one.
>
>? ? ?Another tack is if you know someone with a 16700 mainframe, you
>? ? ?can plug in your 16557D cards and turn on some fairly verbose
>? ? ?debugging during self-test which may lead you to the problem.? I'm
>? ? ?not familiar enough with the 16500C to know if it has something
>? ? ?similar.? Maybe someone else can comment on its debugging
>? ? ?capabilities.
>
>? ? ?-mark
>
>
>
> --
> Damien Towning
>
>
>
--
|
There's also a pretty extensive thread about the corrosion problem on eevblog - mainly focused on the 167xx cards, but the info is basically the same for the 165xx cards as well.
That's kind of the main thread, but there are some smaller threads too that have some good info.
These are also some good pages with good info / pictures:
A solder sucking gun works good for through hole, but if your resistor packs are surface mount (like the ones on the 16752 boards are), get yourself a hot air tool if you don't already have one. You'll wonder how you did anything without it once you have one. Even one of the super cheapie 858D ones will get you a long way, but if you want to spend a little more to get a much nicer tool, I'd recommend a Quick 861DW or the roughly equivalent Atten ST-862D. For the relatively cheap price of those tools, they're really good quality.
The solder sucker gun and the hot air tool are really complimentary tools - each one is good at different things, but they can also work together. If you have through hole parts on huge ground planes without proper thermal vias, and the solder sucker gun just doesn't have enough heat to get things melting, pre-heat the whole area with the hot air, and then go in with the solder sucker to actually free the part.
Thanks for that. That is really helpful. When I looked at the issue as documented here :? I see that my board is a different revision. It is like they realised they had a problem and moved things around. So most of what is under the plastic runners is now visible tracks without via. Only a few seem to have got caught up in the green death. When the microscope turns up I think I will be able to take pictures with it and put them up somewhere. That comment about the resistor packs is a good pointer because at one of one of these rails is indeed a resistor pack. It looked clean but maybe it isn't. I am thinking about getting a solder sucking gun to pull the solder out of any bad via etc. Since it sounds like I will be doing a lot of that!??
On Fri, Nov 17, 2023 at 11:48?AM Harvey White < madyn@...> wrote: Looking at this from the point of view of making PC boards:
Corrosion on the surface kills one track.? That can be cured several
ways and rather easily.
If corrosion covers a via, or a lead for a part, then life can be more
complicated.
The board manufacturing process makes what's effectively an eyelet
between the top and bottom layers.? The inner layers have their own
eyelet (effectively).? When the board is assembled, the plating through
process connects all these layers with the hole plating.
Corrosion can break this bond between layers.? To fix this, you must
know where the inner layers (if any) connect.? That can be a problem
unless you have a working board (and can trace it) or a schematic.
Harvey
On 11/16/2023 5:53 PM, Damien Towning wrote:
> Thanks. I did find an article on fixing these boards buti it was a
> slightly different revision of the board. I've ordered up a decent
> scope so I can see the tracks better. I wonder if anyone can give me
> some details about the vias. The problems I have identified appear not
> to be with the hollow via type pins that go all the way through (
> which have some sort of protective coating on them ) but with the kind
> that appear to join pads together. From the article I read they
> apparently have solder in them that can be sucked out but the ones on
> this board seem like they are solid. Anybody that has any insight in
> to doing this repair I would be interested to hear from.
>
> On Thu, Nov 16, 2023 at 5:57?AM Mark Litwack
> <mlitwack@...> wrote:
>
>? ? ?Hi Damien,
>
>? ? ?There are no schematics available that I've ever seen.? And I
>? ? ?don't know of any analysis cards that don't have this problem to
>? ? ?some extent.? All the analysis cards I've seen have components on
>? ? ?the bottom, and therefore the plastic runners to "protect" them
>? ? ?from getting raked off.
>
>? ? ?You don't say what country you're in, but right now on ebay there
>? ? ?are two 16557D cards for sale in the USA for USD$49.95 each (+
>? ? ?shipping) in "Used" condition, which means they are claimed as
>? ? ?working by the seller.? If you get them and they don't work, you
>? ? ?can return them as "Not as Described", whether the seller accepts
>? ? ?returns or not.? For the ones I see (item #305031279984), the
>? ? ?seller accepts returns anyway.
>
>? ? ?That's inexpensive for these cards, and a factor may be that they
>? ? ?don't have cables, but presumably you don't need those anyway.?
>? ? ?What do you have to lose.
>
>? ? ?You could also try buying one, and if it works use it as a
>? ? ?comparison to fix yours.? It's much easier to fix these corroded
>? ? ?cards if you can compare to a working one.
>
>? ? ?Another tack is if you know someone with a 16700 mainframe, you
>? ? ?can plug in your 16557D cards and turn on some fairly verbose
>? ? ?debugging during self-test which may lead you to the problem.? I'm
>? ? ?not familiar enough with the 16500C to know if it has something
>? ? ?similar.? Maybe someone else can comment on its debugging
>? ? ?capabilities.
>
>? ? ?-mark
>
>
>
> --
> Damien Towning
>
>
>
--
|
To prevent board damage, hot air reworking stations should always be used in conjunction with under board heaters. Under board heaters gently preheat the entire area of the board being worked on to a component and solder safe temperature of around 100-150C. This preheating action makes the hot air gun work fast, without the usual damage from overheating. -Chuck Harris On Fri, 17 Nov 2023 03:27:23 -0800 "Andrew Hakman" <andrew.hakman@...> wrote: A solder sucking gun works good for through hole, but if your resistor
packs are surface mount (like the ones on the 16752 boards are), get
yourself a hot air tool if you don't already have one. You'll wonder
how you did anything without it once you have one. Even one of the
super cheapie 858D ones will get you a long way, but if you want to
spend a little more to get a much nicer tool, I'd recommend a Quick
861DW or the roughly equivalent Atten ST-862D. For the relatively
cheap price of those tools, they're really good quality.
The solder sucker gun and the hot air tool are really complimentary
tools - each one is good at different things, but they can also work
together. If you have through hole parts on huge ground planes
without proper thermal vias, and the solder sucker gun just doesn't
have enough heat to get things melting, pre-heat the whole area with
the hot air, and then go in with the solder sucker to actually free
the part.
|
Using the microscope took some pictures.?
I think in this revision of the board they might have known they had a problem in that only one resistor pack looks to have been exposed to the carnage. I fixed two bad tracks but the rest seem okay. Now with the 'solid' vias(?) should I just be able to heat those up and suck the solder out. Where they join tracks when I scrape em up they just look like copper? If I am supposed to suck those out and reflow em I definitely have something to go work on. With the microscope I can see about four of those that clearly have problems. For the resistor with the corroded leads I was just going to try cleaning those leads up with fresh solder. Do I need to lift that resistor off entirely do you think ? My feeling is the board can be saved if I just know what to do. I can mend a track fine. But these vias that seem solid are new to me.?
On Sat, Nov 18, 2023 at 12:07?AM Chuck Harris < cfharris@...> wrote: To prevent board damage, hot air reworking stations should
always be used in conjunction with under board heaters.
Under board heaters gently preheat the entire area of the
board being worked on to a component and solder safe
temperature of around 100-150C.
This preheating action makes the hot air gun work fast,?
without the usual damage from overheating.
-Chuck Harris
On Fri, 17 Nov 2023 03:27:23 -0800 "Andrew Hakman"
<andrew.hakman@...> wrote:
> A solder sucking gun works good for through hole, but if your resistor
> packs are surface mount (like the ones on the 16752 boards are), get
> yourself a hot air tool if you don't already have one. You'll wonder
> how you did anything without it once you have one. Even one of the
> super cheapie 858D ones will get you a long way, but if you want to
> spend a little more to get a much nicer tool, I'd recommend a Quick
> 861DW or the roughly equivalent Atten ST-862D. For the relatively
> cheap price of those tools, they're really good quality.
>
> The solder sucker gun and the hot air tool are really complimentary
> tools - each one is good at different things, but they can also work
> together. If you have through hole parts on huge ground planes
> without proper thermal vias, and the solder sucker gun just doesn't
> have enough heat to get things melting, pre-heat the whole area with
> the hot air, and then go in with the solder sucker to actually free
> the part.
>
|
It may be more complicated than it looks on the surface.
The plated through holes are often not what you'd think, being more delicate than not.
To visualize this, think a ham sandwich (just because) with a layer of cheese.? The layers are bread, cheese, bread, meat, bread.
Someone has very cleverly drawn a picture in icing on the top and bottom outsides of the bread.
This is how the layers stack.
Now, none of those layers are connected at this instant.
Punch a hole through the sandwich, exactly where you'd want a Via.
Then, rather than fill it with mayonnaise (apologies if you like mustard), paint the inside with a meat paste, it connects the edges of the meat layer and the edges of the cheese layer.
That's the board to board via plating.? It also connects the top to the bottom.
so what you end up with (on the board) is a plated through eyelet that shorts everything on the layers together.? This only happens when it's desired.
Now look at what happens with corrosion.
If the corrosion only makes it to the surface layer, then the top tracks may be damaged, they may not.? The problem happens when the corrosion goes down in the hole and eats away the connection between the via plating and the inner layer.? Even worse, the corrosion can get between the layers and eat away the tracks between the top and bottom layers.
An additional problem is that the corrosion can be conductive.
So with corrosion, if the connection to the via is broken top or bottom, you can readily fix it.? If the damage is internal, you must determine where the internal trace goes, and try to fix that.? This is with the hope that the corrosion has not shorted things out in the internal layers.? Some of the track to track spacing is quite small.
So it may not be as simple as you'd think.
You may be able to trace the? inner track by a process of elimination.? With a known good board (sorry), trace that track using a low voltage ohmmeter (less than a volt should be good), and see where that trace connects.? Since you're putting unwanted voltage on lots of pins, you do want a very low voltage (and current limited ohmmeter).
Others may have a better technique, but perhaps this explains why the fix may not work as well as you'd like.
Harvey
toggle quoted message
Show quoted text
On 11/19/2023 9:41 PM, Damien Towning wrote: Using the microscope took some pictures.
PCB 0 <>
PCB 1 <>
PCB 2 <>
PCB 3 <>
PCB 4 <>
PCB 5 <>
PCB 6 <>
I think in this revision of the board they might have known they had a problem in that only one resistor pack looks to have been exposed to the carnage. I fixed two bad tracks but the rest seem okay. Now with the 'solid' vias(?) should I just be able to heat those up and suck the solder out. Where they join tracks when I scrape em up they just look like copper? If I am supposed to suck those out and reflow em I definitely have something to go work on. With the microscope I can see about four of those that clearly have problems. For the resistor with the corroded leads I was just going to try cleaning those leads up with fresh solder. Do I need to lift that resistor off entirely do you think ? My feeling is the board can be saved if I just know what to do. I can mend a track fine. But these vias that seem solid are new to me.
On Sat, Nov 18, 2023 at 12:07?AM Chuck Harris <cfharris@...> wrote:
To prevent board damage, hot air reworking stations should
always be used in conjunction with under board heaters.
Under board heaters gently preheat the entire area of the
board being worked on to a component and solder safe
temperature of around 100-150C.
This preheating action makes the hot air gun work fast,
without the usual damage from overheating.
-Chuck Harris
On Fri, 17 Nov 2023 03:27:23 -0800 "Andrew Hakman"
<andrew.hakman@...> wrote:
> A solder sucking gun works good for through hole, but if your
resistor
> packs are surface mount (like the ones on the 16752 boards are), get
> yourself a hot air tool if you don't already have one. You'll wonder
> how you did anything without it once you have one. Even one of the
> super cheapie 858D ones will get you a long way, but if you want to
> spend a little more to get a much nicer tool, I'd recommend a Quick
> 861DW or the roughly equivalent Atten ST-862D. For the relatively
> cheap price of those tools, they're really good quality.
>
> The solder sucker gun and the hot air tool are really complimentary
> tools - each one is good at different things, but they can also work
> together. If you have through hole parts on huge ground planes
> without proper thermal vias, and the solder sucker gun just doesn't
> have enough heat to get things melting, pre-heat the whole area with
> the hot air, and then go in with the solder sucker to actually free
> the part.
>
--
Damien Towning
|
In my experience with these boards, the issues are usually around the edges of where the runners used to be - sometimes even a fair ways away from the edges. I don't know the chemistry of what's going on here, but people have suggested it has something to do with the adhesive and moisture exposure in the air over a long period of time, hence why the damage is around the edges.
Any of the vias that are "tented" (aka have solder mask over them) are _usually_ ok, it's the ones that have exposed solder that you need to watch out for. If you heat them, you'll see what I mentioned before about the solder has a very powdery / dry look to it, and a bunch of weird brown goopie chunks will come out of it - it almost looks like flux, but it's not flux. I think the solder actually looks ok-ish, but may not be conductive anymore in some instances. I heat those and reflow fresh solder into them, which helps get all the brown chunks out.
Also sometimes the corrosion gets under the solder mask on the traces - the traces will look normal through the solder mask, but if you scrape the mask a little bit, you'll find powdery metal again.
Any trace that's suspect, try to find the components it goes to and do an end-to-end continuity check across the whole trace. You'll be amazed at what looks ok, but isn't.
My Observations: Picture 1:
Reflow the 4 large VIAs to the right of "OK" above where the runner was. Reflow the test pad in the middle of the track to the left of where the runner was (can barely see it in the picture on the left edge). Right at the corner of the right most track below where the runner was, there's a "green crusty" - anywhere you see green crusties, the track may be damaged under the solder mask. It looks like you may have scraped the mask back on another trace down there already, or maybe that's one that has an issue - it's a different color than the others. The 3rd one from the left where it's turning and going at an angle. Also have a look at the very bottom horizontal trace - the one that's parallel to and just outside of the runner area. It looks suspect.
Picture 2: Reflow the 3 large vias - the one that's under the runner for sure will produce the brown gunk. Try to flush out as much as possible and fill it with fresh solder.
Picture 3: Reflow the 3 large vias - be careful with the one on the right that's copper colored - once they look like that, they are very thin and very easy to lift off the board with too much heat. Also check that one where it transitions from the large via pad to the trace - scrape back the mask a little bit and make sure you get good solder adhesion back into the trace a little bit to that pad.
Picture 4: All of those test pads are suspect in the upper right quadrant of the picture - you can see how the ones closer to the runner look grey / have green crusties around them. The ones further away from where the runner is (lower right) look more normal - silvery and shiny. Reflow the suspect ones making sure to be making good contact to the traces on either side of the test pads.
Picture 5: Looks like picture 2, but slightly more visible in the picture - same comments
Picture 6: All of the large test pads look suspect. All the joints on the component on the very bottom left of the image are suspect (all green and nasty looking). The "brown" look under the solder mask of the trace right in the middle is suspect. There's also a green crustie on the trace to the right of the one with the brown mark - that could be on the surface, or it could be under the mask as well.
Picture 7: Basically the same picture as picture 6, but further down - again the component on the very left side of the image all connections are suspect. That's where I'd be checking right at the opening of the solder mask where the track turns into a pad for breaks. Most of the large vias / test point look bad.
Did you check into if the 16500 mainframe has self tests with detailed info? Those really help to narrow things down. It's very hard to tell visually what's actually bad and what isn't, and you can spend HOURS cleaning up stuff that looks bad on the board, but probably isn't actually creating any real problems.
Using the microscope took some pictures.?
I think in this revision of the board they might have known they had a problem in that only one resistor pack looks to have been exposed to the carnage. I fixed two bad tracks but the rest seem okay. Now with the 'solid' vias(?) should I just be able to heat those up and suck the solder out. Where they join tracks when I scrape em up they just look like copper? If I am supposed to suck those out and reflow em I definitely have something to go work on. With the microscope I can see about four of those that clearly have problems. For the resistor with the corroded leads I was just going to try cleaning those leads up with fresh solder. Do I need to lift that resistor off entirely do you think ? My feeling is the board can be saved if I just know what to do. I can mend a track fine. But these vias that seem solid are new to me.?
On Sat, Nov 18, 2023 at 12:07?AM Chuck Harris < cfharris@...> wrote: To prevent board damage, hot air reworking stations should
always be used in conjunction with under board heaters.
Under board heaters gently preheat the entire area of the
board being worked on to a component and solder safe
temperature of around 100-150C.
This preheating action makes the hot air gun work fast,?
without the usual damage from overheating.
-Chuck Harris
On Fri, 17 Nov 2023 03:27:23 -0800 "Andrew Hakman"
<andrew.hakman@...> wrote:
> A solder sucking gun works good for through hole, but if your resistor
> packs are surface mount (like the ones on the 16752 boards are), get
> yourself a hot air tool if you don't already have one. You'll wonder
> how you did anything without it once you have one. Even one of the
> super cheapie 858D ones will get you a long way, but if you want to
> spend a little more to get a much nicer tool, I'd recommend a Quick
> 861DW or the roughly equivalent Atten ST-862D. For the relatively
> cheap price of those tools, they're really good quality.
>
> The solder sucker gun and the hot air tool are really complimentary
> tools - each one is good at different things, but they can also work
> together. If you have through hole parts on huge ground planes
> without proper thermal vias, and the solder sucker gun just doesn't
> have enough heat to get things melting, pre-heat the whole area with
> the hot air, and then go in with the solder sucker to actually free
> the part.
>
--
|
Yes. I was coming to the errors in the diagnostics. I am waiting for a decent solder sucking station to turn up now. Now that you have pointed out some more of the bad VIA I can see how some I thought were okay were suspect. I am going to wait for the gun because I scraped a few back with a scalpel exposing the copper and I think I did an okay job but I can also see how easy it would be to lift em. Seems like a much more controlled action to suck the solder out of them with a proper tool first. Now for the errors in the diagnostic it is failing the PLD memory path test and it is failing the final ( Step four ) of the memory test on the board. I will power it up again tomorrow and take pictures of those errors. What I have been trying to figure out also is how to telnet in to the thing to get a shell. I was sure I read somewhere I could do this. I can assign it an ip address. I can port scan it and see it is running a time server. But I see not telnet service on a port and no ftp either. Perhaps these were software options that needed to be installed. I had a look through the user manual for it and didn't see much helpful on that. This is really a great learning exercise and even if these boards don't work out I will just keep going and order more till I get one fixed. I've not attempted the other board yet. I figured I would stuff up one at a time. But they both fail in the same way which is interesting. Same error messages.?
In my experience with these boards, the issues are usually around the edges of where the runners used to be - sometimes even a fair ways away from the edges. I don't know the chemistry of what's going on here, but people have suggested it has something to do with the adhesive and moisture exposure in the air over a long period of time, hence why the damage is around the edges.
Any of the vias that are "tented" (aka have solder mask over them) are _usually_ ok, it's the ones that have exposed solder that you need to watch out for. If you heat them, you'll see what I mentioned before about the solder has a very powdery / dry look to it, and a bunch of weird brown goopie chunks will come out of it - it almost looks like flux, but it's not flux. I think the solder actually looks ok-ish, but may not be conductive anymore in some instances. I heat those and reflow fresh solder into them, which helps get all the brown chunks out.
Also sometimes the corrosion gets under the solder mask on the traces - the traces will look normal through the solder mask, but if you scrape the mask a little bit, you'll find powdery metal again.
Any trace that's suspect, try to find the components it goes to and do an end-to-end continuity check across the whole trace. You'll be amazed at what looks ok, but isn't.
My Observations: Picture 1:
Reflow the 4 large VIAs to the right of "OK" above where the runner was. Reflow the test pad in the middle of the track to the left of where the runner was (can barely see it in the picture on the left edge). Right at the corner of the right most track below where the runner was, there's a "green crusty" - anywhere you see green crusties, the track may be damaged under the solder mask. It looks like you may have scraped the mask back on another trace down there already, or maybe that's one that has an issue - it's a different color than the others. The 3rd one from the left where it's turning and going at an angle. Also have a look at the very bottom horizontal trace - the one that's parallel to and just outside of the runner area. It looks suspect.
Picture 2: Reflow the 3 large vias - the one that's under the runner for sure will produce the brown gunk. Try to flush out as much as possible and fill it with fresh solder.
Picture 3: Reflow the 3 large vias - be careful with the one on the right that's copper colored - once they look like that, they are very thin and very easy to lift off the board with too much heat. Also check that one where it transitions from the large via pad to the trace - scrape back the mask a little bit and make sure you get good solder adhesion back into the trace a little bit to that pad.
Picture 4: All of those test pads are suspect in the upper right quadrant of the picture - you can see how the ones closer to the runner look grey / have green crusties around them. The ones further away from where the runner is (lower right) look more normal - silvery and shiny. Reflow the suspect ones making sure to be making good contact to the traces on either side of the test pads.
Picture 5: Looks like picture 2, but slightly more visible in the picture - same comments
Picture 6: All of the large test pads look suspect. All the joints on the component on the very bottom left of the image are suspect (all green and nasty looking). The "brown" look under the solder mask of the trace right in the middle is suspect. There's also a green crustie on the trace to the right of the one with the brown mark - that could be on the surface, or it could be under the mask as well.
Picture 7: Basically the same picture as picture 6, but further down - again the component on the very left side of the image all connections are suspect. That's where I'd be checking right at the opening of the solder mask where the track turns into a pad for breaks. Most of the large vias / test point look bad.
Did you check into if the 16500 mainframe has self tests with detailed info? Those really help to narrow things down. It's very hard to tell visually what's actually bad and what isn't, and you can spend HOURS cleaning up stuff that looks bad on the board, but probably isn't actually creating any real problems.
Using the microscope took some pictures.?
I think in this revision of the board they might have known they had a problem in that only one resistor pack looks to have been exposed to the carnage. I fixed two bad tracks but the rest seem okay. Now with the 'solid' vias(?) should I just be able to heat those up and suck the solder out. Where they join tracks when I scrape em up they just look like copper? If I am supposed to suck those out and reflow em I definitely have something to go work on. With the microscope I can see about four of those that clearly have problems. For the resistor with the corroded leads I was just going to try cleaning those leads up with fresh solder. Do I need to lift that resistor off entirely do you think ? My feeling is the board can be saved if I just know what to do. I can mend a track fine. But these vias that seem solid are new to me.?
On Sat, Nov 18, 2023 at 12:07?AM Chuck Harris < cfharris@...> wrote: To prevent board damage, hot air reworking stations should
always be used in conjunction with under board heaters.
Under board heaters gently preheat the entire area of the
board being worked on to a component and solder safe
temperature of around 100-150C.
This preheating action makes the hot air gun work fast,?
without the usual damage from overheating.
-Chuck Harris
On Fri, 17 Nov 2023 03:27:23 -0800 "Andrew Hakman"
<andrew.hakman@...> wrote:
> A solder sucking gun works good for through hole, but if your resistor
> packs are surface mount (like the ones on the 16752 boards are), get
> yourself a hot air tool if you don't already have one. You'll wonder
> how you did anything without it once you have one. Even one of the
> super cheapie 858D ones will get you a long way, but if you want to
> spend a little more to get a much nicer tool, I'd recommend a Quick
> 861DW or the roughly equivalent Atten ST-862D. For the relatively
> cheap price of those tools, they're really good quality.
>
> The solder sucker gun and the hot air tool are really complimentary
> tools - each one is good at different things, but they can also work
> together. If you have through hole parts on huge ground planes
> without proper thermal vias, and the solder sucker gun just doesn't
> have enough heat to get things melting, pre-heat the whole area with
> the hot air, and then go in with the solder sucker to actually free
> the part.
>
--
|
I'd like to echo Andrew's suggestion of testing the traces from end to end.
It is tedious, but testing each trace that runs under or near where the runners sat may find your problem.? A signal trace will usually surface somewhere on a via, and then go back under again after traveling some distance.? Use a set of fine and extremely sharp test probes to test the continuity.? Jam the probes into the end vias at an angle to pierce the solder mask so that it makes contact with the plating in the via hole.? Don't trust a trace is ok by visual inspection alone.
I have a set of Pomona 6275 with SS tips that I keep sharp with a hone for this task.? You could also make your own sharp probes from sewing needles if these are too expensive for your budget.
Note that most of the larger solder blobs are not vias at all (unless they have a hole in them), but are test pads.? As he also points out, it's a very common spot for corrosion attack since the bare copper is usually exposed around the edge of the solder blob.? You'll also notice that many of the solder blobs just go to a via and nowhere else.? Those are signal test points and not worth worrying about.? The solder blobs where the trace passes through it are the ones to make sure are incorporated in your end-to-end testing.
-mark
|
I think the 16700 and possibly the 16600, which run HPUX on a PA-RISC processor have a telnet client but not the 16500.
It does have some open ports but they don't respond to what i've tried (SCPI commands).
Something I saw while looking for strings in the binary system files indicated they might provide an RPC interface.
|
I have two things. The users reference and the programmers guide. From what I can glean in the users reference it should pop up some sort of programing interface via telnet.? From the user guide,?
"? Telnet or ftp: Initiate a session from your controlling computer. If you are
using telnet, be sure to specify socket 5025. If you are using ftp, log in as
control."?
"Telnet: Type programming commands in directly."?
It will also remote xterm but it seemed simpler just to get Telnet going first. I wonder if that functionality needed to come off something that needs to be installed via disk. The programming guide seems to imply one is sitting in a terminal and able to issue various instructions. Contains example code to feed it.?
On Tue, Nov 21, 2023 at 11:03?AM Adrian Godwin < artgodwin@...> wrote: I think the 16700 and possibly the 16600, which run HPUX on a PA-RISC processor have a telnet client but not the 16500.
It does have some open ports but they don't respond to what i've tried (SCPI commands).
Something I saw while looking for strings in the binary system files indicated they might provide an RPC interface.
|
I just wanted to be clear that when we were talking about the various VIA on the board this is the sort of problem I should be going after? I put red circles next to the things I was planning to go at with the solder sucker when it arrives.
Should I just go after basically all the through hole VIA in the area? What makes it confusing is they put some sort of green coating on the via which makes it hard to tell what is corrosion and what isn't!?
On Tue, Nov 21, 2023 at 11:34?AM Damien Towning via <connolly.damien= [email protected]> wrote: I have two things. The users reference and the programmers guide. From what I can glean in the users reference it should pop up some sort of programing interface via telnet.? From the user guide,?
"? Telnet or ftp: Initiate a session from your controlling computer. If you are
using telnet, be sure to specify socket 5025. If you are using ftp, log in as
control."?
"Telnet: Type programming commands in directly."?
It will also remote xterm but it seemed simpler just to get Telnet going first. I wonder if that functionality needed to come off something that needs to be installed via disk. The programming guide seems to imply one is sitting in a terminal and able to issue various instructions. Contains example code to feed it.?
On Tue, Nov 21, 2023 at 11:03?AM Adrian Godwin < artgodwin@...> wrote: I think the 16700 and possibly the 16600, which run HPUX on a PA-RISC processor have a telnet client but not the 16500.
It does have some open ports but they don't respond to what i've tried (SCPI commands).
Something I saw while looking for strings in the binary system files indicated they might provide an RPC interface.
--
|
Hi Damien,
On your photo, the four larger pads where you've placed a red dot are NOT vias.? They are examples of test points that bring signals to the bottom of the board.? They don't go anywhere else and are provided for probably automated testing, or possibly troubleshooting for HP technical folks.? There are a few pads of this larger size that also have a hole in the center of them in some of your other photos, and those ARE vias combined with a test point.
The three smaller pads you show with red dots are vias and they connect other layers not visible together (thru vias)? The green coating, like a transparent paint, is soldermask.? If the soldermask is intact with no white or green fuzz surrounding it or inside it, the via is probably ok (although not guaranteed).? If it helps, the green fuzz is corroded copper, and the white fuzz is corroded solder.
I'm not sure what the soldersucker is going to do for you in that photo.? You won't find find solder in those via holes.? And the larger test pads in the photo that have solder on them are not part of an operational signal path.
Instead of going after the vias first, I would recommend prioritizing your efforts to find and fix bottom layer tracks that have been severed, including on the component connections such as the resistor packs, and when they pass through a test pad.? I've fixed somewhere around 20 of these series modules by only repairing severed tracks.
I also have a similar number of dead boards, almost all with severe corrosion on multiple thru vias, and some of them so severe that the annular copper ring is completely gone.? Although it's not impossible to fix destroyed vias, at some point you should evaluate if a replacement card for $50 is worth your time so you can get on with your actual application for the 16500C.
So again, I would recommend end-to-end testing of all signal tracks from via to via as a first step before even warming up any soldering equipment.? And start with those in areas where corrosion is showing, and when the tracks cross under or near the former plastic runners.? Don't trust a visual inspection.
When you find a bad track, try to locate the bad section by by moving your probes closer and closer on the track.? You need very sharp probes to get through the soldermask.? When you've zeroed in on the bad section, mark it and move on to the next track.? (I use small red arrow stickers, Brady DIA-250-RD.)? Keep in mind there are sometimes multiple breaks in a track.? After you're done testing, go back and fix everything you found.
Since your boards were working at some point, you might only find one or two problems.
Also, did these two boards die with the exact same error and at the same time?? If so, it's not an impossible coincidence, but it does raise the specter of a problem elsewhere in the system.
-mark
|
Anyone still looking for 16500x boards, this just
appeared a day or two ago:
Have to be near Sacramento, Ca. to be practical,
this is a lot of bulk/weight to ship, plus it must be picked up
"in person".
Shame I'm not closer, I'd like one of the 1660
units for spare parts.
Bill Martin
On 11/15/23 10:57, Mark Litwack wrote:
toggle quoted message
Show quoted text
Hi Damien,
There are no schematics available that I've ever seen.? And I
don't know of any analysis cards that don't have this problem to
some extent.? All the analysis cards I've seen have components on
the bottom, and therefore the plastic runners to "protect" them
from getting raked off.
You don't say what country you're in, but right now on ebay there
are two 16557D cards for sale in the USA for USD$49.95 each (+
shipping) in "Used" condition, which means they are claimed as
working by the seller.? If you get them and they don't work, you
can return them as "Not as Described", whether the seller accepts
returns or not.? For the ones I see (item #305031279984), the
seller accepts returns anyway.
That's inexpensive for these cards, and a factor may be that they
don't have cables, but presumably you don't need those anyway.?
What do you have to lose.
You could also try buying one, and if it works use it as a
comparison to fix yours.? It's much easier to fix these corroded
cards if you can compare to a working one.
Another tack is if you know someone with a 16700 mainframe, you
can plug in your 16557D cards and turn on some fairly verbose
debugging during self-test which may lead you to the problem.? I'm
not familiar enough with the 16500C to know if it has something
similar.? Maybe someone else can comment on its debugging
capabilities.
-mark
|
