68kMLA Classic Interface

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Documenting my IIfx repair

Posted by: Hotdog Zanzibar on 2011-10-08 22:15:28 As I said Thursday, my Classic died the same day as its creator. When I opened it to see if it was a simple matter of cleaning the motherboard, I found one badly-corroded battery and chassis inside. Surprisingly, the Classic had worked just a day prior, when I was doing some software tinkering. I was amazed it would even run with that much corrosion. So this got me to thinking that I should start checking all of my oldest systems for capacitor leaks, burst batteries, etc. Centris 650 = check. Battery was good, no capacitors to worry about. Board & PSU was clean. IIsi = check. Capacitors are good, battery was removed a couple years ago. Clean. Tonight, I brought out the IIfx. Popped it open and was pleased to see both batteries in good shape. Plugged it in, attached a monitor, keyboard, etc, and pressed the power button -- nothing. No chime, no fan, not a sound. There are only two capacitors on the board, from what I can tell: Both show signs of leaking, so I decided to pull the board and wash it. Now, the batteries look good, but they both have "90-09" stamped on them. The machine's build date is September 1990. So these batteries are probably quite dead. This would also keep it from booting, although I would think the PSU would at least turn on. I examined the PSU and there's no sign of any damage, and it's pretty clean. So right now, I'm assuming the problem is either the capacitors or the batteries. Incidentally, both batteries have this weird nick in the positive end: Yet there's no fluid or corrosion anywhere. I removed all the RAM and the ROM SIMM for cleaning. What about the processor? I don't want to try removing it if I don't need to (or am unable to). Is there anything else I should remove before I run it thru the dishwasher?

Posted by: zuiko21 on 2011-10-09 14:43:51 Hi! As far as I know, dead batteries on a Mac II / IIx won't be able to turn on the Power Supply. Not sure about the IIfx, though, but worth a try with fresh batteries before doing anything else. I think you can leave the processor while washing the board... I let mine on my IIx mobo, and now works great! Good luck anyway,

Posted by: 24bit on 2011-10-09 15:31:26 If you have no 3,6 Li's ready, a 9V block should provide trickle power to your psu too, if you want to check if batteries are the problem. Should be easy enough to meter your old batteries too. About the board cleaning, how do you feel about isopronanol? Best wishes!

Posted by: Dennis Nedry on 2011-12-11 11:28:41 Mac II, IIx, and IIfx all require both good batteries to turn on, either that or a jump start directly to the power supply. I am not aware of any single-battery Macs that need good batteries to turn on. The IIci and IIsi do not require a good battery. Some require an on-off-on sequence to turn on with a dead battery, such as all 610/660AV/6100 style Macs. This is why I remove all batteries from all Macs, there is no sense risking an explosion when I can just work with the quirks and fix a few settings each time.

Posted by: Hotdog Zanzibar on 2012-08-05 20:35:20 Still doing this... got sidetracked when I got a new job. The IIfx is still in pieces on my workbench, but I've kind of made room for a Quadra 840AV project I'm working on...

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