NiCd battery replacement in vintage computers
Mark J. Blair
nf6x at nf6x.net
Sun Feb 7 04:45:11 CST 2016
I found a reference which states that the NVRAM is used to hold SCSI controller parameters.
I decided to mount a CR123A holder inside the case on one of the slot filler panels. I had some through-hole PCB mount CR123A holders left over from a previous project. I machined a mounting base for the holder out of a chunk of Delrin on my little Sherline CNC mill, with a diode installed inside the base to protect the battery from being charged as well as providing reverse polarity protection. The CR123A cells I have sitting around are 10 years old, but one of them will do until I buy some fresh ones.
I physically debrided the corroded copper from the top layer. I hope the rot didn't get into inner layers, but at least it didn't make it to the bottom of the board.
I posted some pictures on Twitter:
I haven't hooked up the machine and booted it again yet, but I can see the RTC oscillator running off the CR123A cell with an oscilloscope.
Mark J. Blair, NF6X <nf6x at nf6x.net>
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