I bought this IIgs board that has some issues. It's missing two caps: C43 and C44. Can someone let me know what caps are supposed to go here?
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Obviously the battery is missing too. There are no leads. It is possible to still install one?
C43 22uF 16v
C44 22uF 16v
ROM3 usually has a battery holder vs just leads. So you can run new wires/leada to the vias where the battery holder should have been.
The board is pretty seriously damaged by the usual Maxell holocaust, although not the worst I have seen.
You can see that the soldermask has bubbled. That means that battery electrolyte has gotten under it and is attacking the copper.
To repair this board you need to completely remove the electrolyte, or it will cause continued corrosion. That corrosion will be even worse if power is applied.
It's easier to just use this kind of damaged board as a parts donor.
How is the electrolyte completely removed? So yes, I get it may be easier to scrap but I am curious about the process.
You would have to remove all of the components and either sand the soldermask (which is an acrylic lacquer) away to expose the copper, or strip it away using a solvent like DCM or THF. Then the copper can be washed to remove all traces of thionyl chloride.
At that point you would be able to start building back up, first by repairing any copper traces that were broken, and installing eyelets in place of corroded vias. Then paint on new green soldermask and reinstall/install new components after testing each trace for continuity.
The process would take several hours and success isn't guaranteed. This is called "Beyond Economic Repair" (BER) in the industry since ROM03 units without damage can still be bought for <$300. Eventually they will all run out and the price will start to climb, as it already has for Macintosh IIfx and SE/30 models that had the same exploding batteries installed.
Repair procedures can be found in IPC-7721 manuals, and supplies are available from companies such as CircuitMedic.
In looking for ROM 3 boards, I haven't found one yet - at any price. The area in this case appears to be very small. Obviously it could be deeper than it appears. Sigh.
I can't tell what used to be there. If I attempt to neutralize the leaky electrolytes, was it a lithium battery or was it an alkaline? ROM 03 would indicate it was likely an alkaline.
It originally used a 1/2A battery. I've only seen those in lithium personally.
Slight correction - it is actually a 1/2 AA 3.6V battery. And yes, all the one's I've seen are lithium also. The most common one I've seen in IIgs's is the Tadiran branded batteries (purple). They are still widely available for purchase.
I assume you've already tried to power up the board? What happens?
Sorry - should have mentioned...
When I power up the board, it alternates between the Config screen and self diagnositcs. I know that a bad ADB connection to the keyboard could result in the Config screen, but it would show whether or not the keyboard was plugged in. It appeared that the repeatable was that if there was absolutely nothing plugged in and the system "rested" overnight, I woiuld get the "Check system disk" screen, but if I plugged anything in (wDrive/3.5/5.25) it would go to the diagnostics and not recognize any drive plugged in. If the system was "warm" at all, then I got the Config screen and it will not accept any keyboard input to get past it.