HP 53131A has dissolved rubber on board, How to clean?

[5065AGuru]

Hi, I just got a parts unit 53131A that was missing the power supply. I have a spare supply so I hoped I could get it working.
However the main board is covered in goop around the area that the rubber spacer of the power supply sat above.
Also on the bottom the area around where another spacer sat is covered with residue.
Looks like both spacers liquified and spread over the board!
I stuck probes onto the black goo on the top and it has a resistance of around 5 giga-Ohm. (1/8" spacing banana jacks)
Wondered if I could try powering it up as is or would I be safer to somehow clean off the goop!
Any suggestions on how to safely get it off without damaging anything???

Cheers,

Corby

[TERRA Operative]

That's looking rather... interesting on the top there.... I had the same with the rubber pad on the bottom. Isopropyl alcohol will clean it right up.

The melted rubber won't cause any short circuit etc, but best not to leave it there.



Also, if you have the means for recalibration, and a firmware earlier than version 3944, you can upgrade it, firmware images here.
If you have a firmware other than 3643 or 3944 and a chip programmer, please do share!

[5065AGuru]

Well I reassembled it without cleaning the board and installed the new power supply.
It comes up just fine and is working great!
I'll just say it's conformal coating!

How do I tell what firmware it has?

Cheers,
Corby

[TERRA Operative]

The firmware version can be displayed by holding down the 'recall' button and turning the unit on, also you can check the stickers on the 4 ROM chips.
It might be worth updating if you can, there were known bugs in the earlier firmwares.

If you are lucky, you'll have EEPROM chips (My 53132A did) so you can just flash the new firmware onto them, if you have one time programmable EPROM chips (like my 53181A had) you'll need to get new chips to program the new firmware into.
For reference, the EEPROM chips in my 53132A are 28F010 and the OTP EPROM's in the 53181A are 27C010, both in PLCC 32 packages. Any equivalent with -150 or lower number for the speed rating should work fine.



Be careful leaving the goop there, it may or may not end up corrosive...