Electronics > Repair

Series defect on agilent 167xx boards?

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benoar:
Hello everyone, new 167xx owner here and new participant to the forum.

Just got a broken 16750A that I am trying to fix: spotted a broken delay line before buying, did not care much about losing 1/4 of the inputs, but when it arrived it was also missing a ferrite, so no testing possible right now. I also looked at the corrosion and… it is quite bad. For example, attached is a photo of a broken trace by corrosion (tested, no continuity), and another one of the PCB after removing a runner, which peeled the solder mask on some areas. You can also see R519 badly corroded: it came off while removing the runner, too.

I cleaned it with IPA and then tried to tin the traces to protect them. but got more mishap while at it: ripped off a pad (test point) presumably because I was too quick and maybe forgot to dry the IPA, or my iron was too hot (370°C; went to 280°C and still working fine with SnPb); it “popped”, but I continued a bit and tore it off (I was thinking it was maybe because of some discharge because my shitty wallwart-supplied hobbyist Weller leaks current like hell; my ESD wristband tingles when it heats up sometimes…). Also accidentally cut another trace somewhere else with my knife when removing adhesive. Then injured myself with the knife and stopped for the moment. Another photo from the result of peeling the runner with a knife: solder mask is cut off in a lot of small places, not very nice. Maybe I should go the heat-gun way.

I will report if I get anywhere with that.

TK:
There lots of vias that are corroded and they internal traces could be damaged, making it extremely difficult to repair this boards

keitheevblog:
While I know this doesn't help any of you that already have corrosion on your boards, I've recently done some runner replacements and wanted to share an update.


* I'm silicone-conformally coating any potentially problem area underneath the removed runners, after cleaning, for future protection.
* I decided on 3M 442KW adhesive tape. I really like this tape, working beautifully. Don't order from digi-key, their stock is old. If you're in US, order from ULINE.
* I do think that being proactive with these is the prudent approach, but there is a risk during runner removal. Take your time.
My updated blog post is https://www.techtravels.org/2019/12/corrosion-near-underneath-hp-logic-analyzer-module-plastic-runners/.

Hope this helps!

nikodem:
Hi!

I seem to have the same problem. I've recently got a faulty 16750A, that when self-tested returned the following:



Unfortunately I don't know how to make any more sophisticated tests. If anyone could point me to a simplish tutorial about that or give some other info I would be very glad :).

And I have noticed the green globs of corrosion sticking from underneath the plastic sliders. I have removed some of them, and the sticky tape is totally dry.

So, my questions is - is it possible, that the self-test failures are due to the corroded tracks? Or is it obvious, that the reason is totally different? I'm asking this, before I spend few hours cleaning the board with IPA and/or acetone from this crap  ::).

keitheevblog:
Hey there,

Most of the tests that you're running via that GUI interface are the same tests. What you need to do is telnet into the box(Username:root, pw "uh,uhuh", access the shell, and run the pv command. You can hit ? for help, and most of it is self explanatory. You either select a specific module (or have it execute against all of them), and then pick which tests (or all of them) to run.

There are a couple ways to increase the verbosity of the debugging output.

Are you far enough along to know how to do those steps above?

EDIT: And yes, there's a VERY good chance that the test failures are directly related to the corrosion.

Keith

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