Electronics > Repair
Series defect on agilent 167xx boards?
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dorkshoei:

--- Quote from: FrodeM on April 18, 2024, 07:16:31 pm ---I just though this might be worthwhile to mention..

Got a 16534A today, with crusty rails. Fortunately, no matter how bad it looked, the card passed the GUI selftests

--- End quote ---

You need to see if it will pass calibration using the T cable described in the manual.       I have one that passes self-test that totally fails the calibration procedure with a fatal error.
MarkL:
I have a bunch of 16534A cards, and almost all of them had corrosion on the mounting bracket for the ADC.  I removed the bracket, removed the corrosion with a wire brush, and sealed the bracket with clear insulating varnish (Sprayon EL600).  And of course removed the plastic runners and their evil adhesive from the board.

It would be great to discover the actual chemical reaction that's happening so it can be neutralized properly.

And 100% agree with dorkshoei.  I've had self-test pass but calibration fail on a number of cards.  A couple of the boards had out of spec rail voltages from the local voltage regulators because of bad output voltage setting resistors.  Replacing the resistors fixed the rail voltages and allowed them to pass calibration.
FrodeM:
I spoke too soon, after removing the rails it no longer pass selftest.

Today I went over with flux, a soldering iron and a microscope. Three of the thin lines that just looked discolorated at a spot ended up disintegrating, so I had to fix that. I also reflowed most components with visible corrosion on the solder pads. Two vias had corrosion into them, but one were connected to one planar layer and seems to make connection. For the other I found fresh metal before the in-board junction.

I will test it tomorrow, since I need to fix the power-supply of the analyzer again. Despite the grid voltage should be 230V according to the power company, during nighttime it can at times be as high as 240V. Either it's that that blows the regulators, or the PSU has an inherent design defect that triggers if you turn the analyzer off and then on again only a few minutes later.
FrodeM:

--- Quote from: MarkL on April 19, 2024, 12:24:57 am ---I have a bunch of 16534A cards, and almost all of them had corrosion on the mounting bracket for the ADC.  I removed the bracket, removed the corrosion with a wire brush, and sealed the bracket with clear insulating varnish (Sprayon EL600).  And of course removed the plastic runners and their evil adhesive from the board.

It would be great to discover the actual chemical reaction that's happening so it can be neutralized properly.

--- End quote ---

Ok, put in the spare PSU. Good news is that the card passes self-test again after the repairs. Crossing my fingers for the calibration.

*Edit*
I reset to default and ran the calibration again after the screenshot, and it seems to pass fine, yay!
darkroom:
How are you guys removing the evil rails/glue from the bottom of the boards?  One site I read said IPA, but I am curious if heat will work?  Thanks!
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