I'll second Jeff's suggestion. Most of the sockets used in commercial stuff have tin-plate pins, with which contact degrades over time. Like Jeff, I've had cases where merely unplugging a seeming-defective part and then reinstalling it was all the "repair" that was needed. This can also apply to edge connectors.

The other possibility if a "replug" fixes a recalcitrant circuit is one or more flaky solder joints connecting the socket to the board are present.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

Yep, I've had that happen too, where only partially pulling ICs out of their sockets (not even all the way out) and pushing them back in fixed it.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

We used to regularly do that on Basic Four minicomputers, especially the DRAM chips used in the smaller units (bigger ones used SIPPs, which had their own special problems). Most of the time, I'd just give a chip a firm push, which was enough to clear up any dodgy connections. Clients would be amazed at my "wizardy" when the machine would boot after me apparently having done nothing except touch one or two chips.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!

From:

http://lowendmac.com/2015/apple-iii-cha ... t-failure/



Mike B.

On the topic of tarnished pins and bad connections, at least a few people have found a need to plug and unplug a connector onto their Acorn's Tube port a couple of dozen times before it comes reliable. Now, those ports will be well over 30 years old and never used until recently, so it's a bit of an extreme case - but in this hobby we do come across pretty old components and equipment.

I've definitely dealt with my fair share of having to reseat chips, restoring some computers in my free time.

Sadly though, I put the old processor back in, and the behavior returned. No sweat though, I will get another one and the GAL chip to restore my Apple IIe, and enjoy my now working breadboard computer! I have to figure out what to do with it now, but I can make it do more than just my monitor now, at least.

Thanks everyone for the continued help over the past year or so. Glad to say I'm done pulling out my hair out over this thing for now.