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Battery-bombed MicroVAX 3100/90

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Beanicles

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Apr 13, 2024
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I have a MicroVAX 3100/90 that sadly has suffered damage due to a leaking NiCAD battery.

I've cleaned the board as best I can with diluted vinegar then washed down with deionised water and IPA.

C14 and C15 don't look too great, and I've removed all of the RAM from those banks.

On powering on I get no serial output whatsoever, and the diagnostic/status LED's indicate 1000 1111 immediately and don't progress any further. Using a manual I found here: https://www.manualslib.com/manual/1617905/Digital-Equipment-Vaxstation-4000-90.html?page=398#manual (granted this is for a VAXstation 4000 but my Google ability wasn't finding a more appropriate manual that actual listed the interpretation of these LED's) I can determine that the device is "system board" but there's no further information as to which subsection 1111 refers to.

I've attached a photo of the damage PRIOR to cleanup to give an idea of the extent. Should I give this up as a lost cause, or is it worth me persevering with trying to recover it, do you think?

I'm comfortable with SMD rework at the pitch of components in the affected area, although solder behaves strangely when it's encountered the dreaded green battery crud.

Any advice, interpretation or input gratefully received.
 

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Too sad, I do have a 4000-105a, same board, same leakage. After weeks I got it to respond. Still it does not like the memory ...
3100-90 and 4000-100 are close, 4000/90 is different. Look for 3100-90, there is manuals. Look for the CPU type
 
Schroeder said:
Too sad, I do have a 4000-105a, same board, same leakage. After weeks I got it to respond. Still it does not like the memory ...
3100-90 and 4000-100 are close, 4000/90 is different. Look for 3100-90, there is manuals. Look for the CPU type
Click to expand...
Would you be able to elaborate on what steps you took to get it to respond?

I’ll try harder to find a diagnostics guide for my board…
 
Depends on your patience and level of skill. It looks like most of the Cypress parts and at least two DIMM sockets will have to be removed. I hope you have a good SMD hot air station.

Given that they are $500+ on ebay, I'd say it is worth it.

CW
 
I would try bathing the complete board in hot citric acid (approx 10min) to neutralize the alkaline, use a toothbrush to clean the affected areas. Then thoroughly rinse the board with clean water. Wait some days for all moisture to evaporate before switching on the machine again.

If this does not work out, I would try to get fresh parts and re-populate the affected areas including the RAM sockets.

I would not give up hope, there are a lot of Amiga 2000,3000,4000 with similar damages brought back to life successfully.
 
I would check every cap to make sure none of them have failed short. This one looks pretty messy

1713055437772.png

DougM
 
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