Electronics > Repair
Series defect on agilent 167xx boards?
MarkL:
--- Quote from: darkroom on August 28, 2024, 01:39:33 pm ---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!
--- End quote ---
Yes on the heat. My method, from earlier in the thread:
https://www.eevblog.com/forum/repair/series-defect-on-agilent-167xx-boards/msg3536942/#msg3536942
Keith has a detailed write-up which is pretty much the same:
https://www.techtravels.org/2019/12/corrosion-near-underneath-hp-logic-analyzer-module-plastic-runners/
aeg:
I use heat and dental floss to separate the rails from the foam tape, then heat and plastic cut from an old credit card to separate the foam tape from the PCB, then alcohol and a Q-tip to remove the remaining residue. For mushy foam, I found that scraping/pushing from the side was more effective than trying to peel it away in the long direction. Your mileage may vary.
FrodeM:
--- Quote from: darkroom on August 28, 2024, 01:39:33 pm ---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!
--- End quote ---
I usually use the edge of the removed plastic-rail runner itself to just scrape whatever residue is left off with a little bit of elbow-grease. That works fairly well, and the plastic is soft enough to not damage the silk-screen and solder-mask layers - even if you put a fair bit of force behind it.
As mentioned in the other techniques, the edge will get a little dull quickly. However that's not an issue for me since I don't tend to re-attach the runners.
darkroom:
Thank you for the replies!
I removed the rails on my 16717A boards with heat with ease. They literally peeled off nicely. Unfortunately (or fortunately I guess), no corrosion underneath...so that's not the issue with those boards.
I removed the rails on my 16754A board (up-resistor'd to a 16756A). The rails came off fine, but the "tape" was hard and crusty and took a LOT of work to get off. GooGone seemed to be the best to soften it up, then scrape it off with one of the 16717a wider rails beveled ends worked fine. Unfortunately, no corrosion under those rails either.
Both boards do have a few vias corroded, so I'll buzz those out.
The documentation for the 16754A says that in Timing mode it supports all channels, so I expected all four pods could be configured for timing mode. But only A & B can be configured for Timing mode. C & D has that option grey'd out. Anyone able to get all 64/68 channels working on a 1675xA board in Timing mode? Or is the documentation just wrong?
The document I am referring to is Agilent-16754A-Specifications-53790.pdf. It says:
"4 GHz “timing zoom” (simultaneous timing analysis on all channels) with 64 K memory depth"
And in the service manual:
" Full-Channel Mode Half-Channel Mode
Maximum Conventional Timing Rate 600 MHz 1.2 GHz
Sample Rate, Timing Zoom 4 GHz 4 GHz
Channel Count per Card 68 34"
I have 4 16754A boards on their way, and I will check them before modifying them.
darkroom:
I figured it out! In Pod Assignments, it showed two Analyzers. Analyzer 1 had pods A & B, and Analyzer 2 had pods C & D. There was no obvious way, to me at least, to get C & D to Analyzer A, nor did I guess I needed to. So, for some strange reason, I decided to try dragging C & D into Analyzer 1....and it worked! I now have all 64 channels available for timing! The only limit I see now is 32 channels per label. But I don't think I will run into that issue very often.
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