On Dec 17, 2016 12:09 PM, "Herb Johnson via vcf-midatlantic" < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I have a SASI XEBEC 104526 rev 4 that works ok when there is a fan blowing on it but overheats after a while. Is there a common component that fails more often in SASI controllers but not IDE and others of the era?
Short answer: I don't know, but here's how to diagnose heat-failing components: controlled heat and freeze. The trick is in finding the physical location.
I simply don't know if there's a common component on XEBEC products which fails. I do know there are heat-related failures on decades-old computers; so I look for such things when I repair them. Obviously one can just replace "hot" components, but they may not be the source of the problem. Long-term, excessive heat is an enemy.
Small hand-held IR thermometers are your friend. I bought one at Radio Shack decades ago for $50. Now they are $15; I'm still using my first one.
If you freeze-spray a hot component and the board operates again, you've established cause-and-effect.
A temperature-related failure mode can be a solder joint. Or a printed-circuit board through-hole which does not contain (enough) solder: the copper plating of the hole cracks over time and separates when hot or flexed. Components can crack too.
I isolate heat-failing components, by putting the board in a freezer, then I install the board back in the device, after heating a SELECTED portion of the board with a hair dryer. Heating different parts of the board, and smaller sections, in succession, should isolate the failing location.
"Teach a person to fish...."
Honestly I was just looking for anyone who worked on these when they were new. I guess I did not state my question clearly enough. The reason I was asking was to see if anyone found these clunky back then out of the box. SASI controllers seem to have been less reliable than other drive controllers, all else being equal eh? Thanks anyway. Bill