13 Sep
2013
13 Sep
'13
1:07 p.m.
Hi, All,
A list member recently sent me a broken Mac128 logic board. I quickly
found a bad solder joint from a previous repair where one of the
original 64Kbit DRAMs was replaced with a socket, but I'm still having
issues.
Hmm.. This worries me.
My experience is that Apple PCBs of that vintage are not the highest
quality and that it's quite easy to damage the through-hole plating.
Given that there was already a bad joint on the replacement socket, I
wonder if there's other damage.
Have you tried 'buzzing out' all the pins on the socket (and other RAMs
if you want to be sure) to wherever they should go (address muxes, data
bus, timing/control PALs). My first guess would be an open connection
somewhere.
-tony