A501

[orange]

my a501 RAM expansion (rev 5) is broken  :-( . I tried replacing everything exccept chips, but it still doesn't work..
the battery has been removed after it leaked badly. BTW, can A501 work without batt?
all resistors and capacitors (except tantalum) are 100%fine
what could be wrong? strangely clock works great, but fast_ram=0 kb.




PS. yes, I know it probably isn't worth 2$, but it would be nice to see it working.

[TjLaZer]

I had a Microbotics card that also suffered from batt leakage.  It also did not work.  Fortunately all the RAM chips are socketted.  I removed the chips and cleaned the board and it works now.  I tested it with no battery and it worked.

[Argus]

There is probably acid damage to a trace that would be more trouble that it's worth to repair.  Too bad the A501 has such a problem and unfortunately battery leakage is not seen until it's too late, due to the soldered rf shield hiding routine inspection.  I've done a few lithium battery hacks to the A501s I have just so I don't have to worry about the battery leaking.

[orange]

but I have checked conductivity of all traces that have changed color, and its fine. BTW, I hope its not multilayer PCB, right?

[Bandaid]

On the older revision A501 (the one with the brownish PCB and 16 256Kbit X 1 DRAMS (120ns) there are only two layers in total (top & bottom).

I've recently modified my A501 to do the lithium coin battery mod.  I had to remove much of the copper around the solder pads where the NiCad was soldered, otherwise I would've needed a 100W soldering gun with all that heat-wicking copper in place.  Holding the board up to the light I can definitely say there are only 2 layers.  IIRC mine is a Rev 5 A501.