Re: HP 16500C looking for logic analyser boards that are functional
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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
>
>
>
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