Re: HP3400A Nonlinearities
The custom scale compensates for nonlinearity in the meter movement itself, not the instrument the meter is installed in.
Dave Wise
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There have been several posts recently both here and on other sites concerning the replacement of the chopper amplifier board in the HP 3400A meters.? I myself have made a couple of different ones over the years, both with different zero drift amplifiers
and one with an active filter for the meter circuit, and today I finally remembered that HP did the meter scales on a custom meter by meter basis to keep accuracy in the presence of system nonlinearities.? On thinking about it a bit, and looking over the various
schematics, my initial feeling is that the majority of any nonlinearities present are due to the thermocouple matching and response - does anyone else know more about this??
Hal
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Re: HP 8350B sweeper behavior
Hi all,
I can hardly believe what I saw when I took out the A6-board. A capacitor with only one leg... what the heck is so special about this one that its so different to all the others - and leaking, too!
Well, as a replacement for the odd value of 300uF I found a 470uF 40V that fit into the support. Now the CW-Filter switch is working and the spectrum looks clean until down to 100kHz span with 1kHz RBW.? Merci Yves!
Attached some pics of the cap. Enjoy!
cheers
Martin
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Re: HP 3400A Upgrade PCBs Available
David - you mention you are doing your own replacement for this board - if you are still in the design stage i would suggest you look at the OPA182 for the chopper amp - I used it in one I did a while back along with a very-much-overkill OPA197 for the output/meter driver (I had several available) and have had flawless operation - it's my daily driver on the bench.? Pretty much just duplicated HP's design other than the new parts and of course deleting the offset adjustment pot / quiescent current resistor required for the original MC3476.
Hal
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Re: HP 3400A Upgrade PCBs Available
On Sun, Nov 19, 2023 at 06:24 AM, factory wrote:
Also I've found there was an 03400-66512 Rev D board, but the manual fails to cover that. Has anyone got a good picture of that board showing both sides? As I'm currently working on making my own version of this board.
David
I'm *think* that I have one that has this revision - I'll check this evening and post pictures if I do. Hal
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Re: HP 3400A Upgrade PCBs Available
I have the 03400-90013 version from Artek and it is a very good and clear scan of the manual with full page schematics and bookmarks - typical Artek quality... maybe your copy was overwritten or something?? I've accidently deleted a file before and they cheerfully resent it to me.
Hal
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Re: HP 3400A Upgrade PCBs Available
Strange . Not listed as available. Must be sold out .?
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Re: HP 8350B sweeper behavior
Hi Martin,
One important detail. is that the CW filter is only active when the 8350 is in CW mode.
If the 8350 is set to a center frequency and zero span, its still in "sweep mode", and the CW filter is deactivated. The led on the CW filter button is still on, even if the filter is disabled due to the 8350 is in sweep mode.
Regards, Askild
On 20. Nov 2023, at 06:35, Yves Tardif <yves_tardif@...> wrote:
> if the trace is still noisy, whether or not you activate the CW filter...
Bonjour Yves,
The trace is as noisy with or without CW-filter. I already wondered what this CW button is doing at all :-)
When its on, the LED behind is not as bright as the others, perhaps there's a reason.
Thanks for the details, will check circuit diagram and inside!
cheers
Martin
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Re: HP 3400A Upgrade PCBs Available
On Sun, Nov 19, 2023 at 06:24 AM, factory wrote:
The original boards with edge connectors were nickel or gold plated, the ones I saw on ebay looked to be HASL, this could be a problem with the gold edge connector sockets, a warning from an ex-HP designer that they can get quite stuck here;
I prefer my HP TE to be original where possible, but I do have a 1976 prefix design Rev. that got modernized by HP with a 03400-66512 Rev C board from 1984.
I've got quite a few 3400As, can't remember the PSUs causing much trouble, except where an incorrect manual was used by a previous repairer & Ge/Si parts got mixed up, some diodes & resistors changed for biasing, all mine are using Ge power transistors, TO-3 parts are getting pretty much obsolete these days anyway, so finding genuine parts from reputable suppliers is a problem.
Wonder what people are doing with the old but still working A6 boards? Noting the large & small optical chopper assemblies were used in other HP analog meters & some DVMs.
One thing I've never found is a decent readable manual for the later serial prefix of the 3400A, I tried the manual bundle from Artek, the 03400-OSM-90008 is a decent scan of the 1972 manual (marked part no. 01768 on the pages), the 1972 03400-90008 is available for free download, but I haven't checked how much it differs. But the 03400-90013 is the exact same one available by download from Agilent/Keysight, the scan quality isn't great.
Has anyone got a decent scan covering the later variants? i.e. A6 with part no. 03400-66512 Rev A & C,
Also I've found there was an 03400-66512 Rev D board, but the manual fails to cover that. Has anyone got a good picture of that board showing both sides? As I'm currently working on making my own version of this board.
David
David, I have a PDF of the 03400-90013 manual that I downloaded from Didier's manual site (serial prefix 2415), It contains a readable schematic & parts placement for the 03400-66512 A6 board.? Not sure if the A6 covered is the version you're looking for; I don't know how to identify the board version covered in the manual. Both of my 3400As have the optical chopper (and still working well), so I can't help with a picture of the board you want. It's the best scan that I've found for the 03400-90013 manual.?? http://www.ko4bb.com/getsimple/index.php?id=download&file=HP_Agilent/HP_3400A_RMS_Voltmeter/HP_3400A_RMS_Voltmeter_Service_Manual.pdf On the impedance converter; according to the circuit description in the manual, it's just a unity gain non-inverting amp with hi input impedance and low output impedance, so that stage should be pretty easy to replace with many of today's opamps.?? Cheers, DaveM
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Re: OT Weinschel/Aeroflex 8310 programmable attenuator
Probably not good for professionals, but cheap and usable for hobbyists.
Ciao.
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Re: HP 16500C looking for logic analyser boards that are functional
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
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There have been several posts recently both here and on other sites concerning the replacement of the chopper amplifier board in the HP 3400A meters.? I myself have made a couple of different ones over the years, both with different zero drift amplifiers and one with an active filter for the meter circuit, and today I finally remembered that HP did the meter scales on a custom meter by meter basis to keep accuracy in the presence of system nonlinearities.? On thinking about it a bit, and looking over the various schematics, my initial feeling is that the majority of any nonlinearities present are due to the thermocouple matching and response - does anyone else know more about this??
Hal
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Re: HP 8350B sweeper behaviour
Hi Chuck,
thanks for reminder on BT1 battery inside the HP8350B.
In the two units that I have both were still present and already
corroded but no damage done yet the HP 8350B.
If you wish to rebuild the memory backup function, on
there is
nice 3D model to print a fresh battery holder.
Regards
Rens | PA3AXA
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Re: HP 8350B sweeper behavior
On 20. Nov 2023, at 06:35, Yves Tardif <yves_tardif@...> wrote: if the trace is still noisy, whether or not you activate the CW filter... Bonjour Yves, The trace is as noisy with or without CW-filter. I already wondered what this CW button is doing at all :-) When its on, the LED behind is not as bright as the others, perhaps there's a reason. Thanks for the details, will check circuit diagram and inside! cheers Martin
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Re: HP 16500C looking for logic analyser boards that are functional
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.
>
--
|
Re: HP 16500C looking for logic analyser boards that are functional
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.
>
--
|
Re: HP 8350B sweeper behavior
Martin,
if the trace is still noisy, whether or not you activate the CW filter on
your 83522A, the circuit involved in this filter is very simple: on the A6
module, it is a U22 driver, a K1 relay and a capacitor C14, 330uF 40V.
Regards
Yves
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-----Message d'origine----- De?: yves_tardif@... <yves_tardif@...> Envoy¨¦?: 19 novembre 2023 20:18 ??: ' [email protected]' < [email protected]> Objet?: RE: [HP-Agilent-Keysight-equipment] HP 8350B sweeper behavior Martin, I'm back... My 8350B, on which I was testing, suddenly broke down, when it was turned back on, it was working 30 seconds earlier...what a coincidence! But, it wasn't too complicated: a capacitor shorted on the +5V power supply on the processor board. By removing the PCBs one by one, I was able to quickly locate the source of the problem. As for the noise on the 1GHz signal, my Spectrum probably has more flexibility, I adjusted the parameters to have exactly yours, based on the image you sent earlier today. Apart from the selectivity of the 10kHz resBW filter which is a little different, I would say that the noise floor is approximately the same as well as the amplitude, the signal shown on your Spectrum shows relatively a lot of noise. However, by default the CW filter should be activated on your plug-in, if this is not the case, do it and compare the result with the image (with/without CW filter). If the image looks like the one on the right with the CW filter ON, then there is no problem. If the CW filter was enabled when you created an image of your Spectrum, then there is a problem...but if so I think it will be quite simple to fix. Do the test and tell me the result, I will tell you which circuit is involved in this process. -----Message d'origine----- De?: [email protected]< [email protected]> De la part de Martin via groups.io Envoy¨¦?: 19 novembre 2023 13:39 ??: [email protected]Objet?: Re: [HP-Agilent-Keysight-equipment] HP 8350B sweeper behavior On 19 Nov 2023, at 18:50, Jeff Kruth via groups.io <kmec@...> wrote: What is interesting to me is the expectation of greater accuracy than was possible... I'm probably spoiled by these synthesised generators. When I was at school, many years ago, I build a generator myself. Certainly horrible performance, but I did not have any tools to measure that. Now I have the tools, so... But what about the noisy SA trace of the 83522A, compared to Yves's trace or the one from the older module? cheers Martin
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Re: HP 16500C looking for logic analyser boards that are functional
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
|
Re: HP 16500C looking for logic analyser boards that are functional
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.
>
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Re: HP 8350B sweeper behavior
Martin,
I'm back...
My 8350B, on which I was testing, suddenly broke down, when it was turned
back on, it was working 30 seconds earlier...what a coincidence! But, it
wasn't too complicated: a capacitor shorted on the +5V power supply on the
processor board. By removing the PCBs one by one, I was able to quickly
locate the source of the problem.
As for the noise on the 1GHz signal, my Spectrum probably has more
flexibility, I adjusted the parameters to have exactly yours, based on the
image you sent earlier today. Apart from the selectivity of the 10kHz resBW
filter which is a little different, I would say that the noise floor is
approximately the same as well as the amplitude, the signal shown on your
Spectrum shows relatively a lot of noise.
However, by default the CW filter should be activated on your plug-in, if
this is not the case, do it and compare the result with the image
(with/without CW filter).
If the image looks like the one on the right with the CW filter ON, then
there is no problem.
If the CW filter was enabled when you created an image of your Spectrum,
then there is a problem...but if so I think it will be quite simple to fix.
Do the test and tell me the result, I will tell you which circuit is
involved in this process.
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-----Message d'origine----- De?: [email protected]< [email protected]> De la part de Martin via groups.io Envoy¨¦?: 19 novembre 2023 13:39 ??: [email protected]Objet?: Re: [HP-Agilent-Keysight-equipment] HP 8350B sweeper behaviour On 19 Nov 2023, at 18:50, Jeff Kruth via groups.io <kmec@...> wrote: What is interesting to me is the expectation of greater accuracy than was possible... I'm probably spoiled by these synthesised generators. When I was at school, many years ago, I build a generator myself. Certainly horrible performance, but I did not have any tools to measure that. Now I have the tools, so... But what about the noisy SA trace of the 83522A, compared to Yves's trace or the one from the older module? cheers Martin
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HP3400A open hardware pcb -- Any interest?
I made a simple test case circuit board and connectors in 2012 and sold 240 of them with no complaints -- the 7k_flex_extender kit.
I have a couple of 3400As and might do a free published chopper board. Is the A2 impedance converter always needed?
And the power supply -- is the problem of obsolete nuvistors possible to fix with a daughter board?
I suppose a set of three boards at 57 EUR is an OK price, but would like it to be open so it can be improved easily, and cost even less.
Anyone interested? Please respond off list and I'll see if enough of a buying group can wait to get some open hardware.
This would of course take a while, so only those not in a rush need respond.
The price for a single bare board with gold flashed fingers sent to US addresses from Albuquerque can be 25 USD each including shipping.
I use free and open tools pcb-rnd and sch-rnd and will be able to translate the pcb design into KiCAD as well.
John Griessen
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Martin
Harold Foster
Emanuele Girlando
