[vcf-midatlantic] Bag-o-chips sorting, storing, testing

[Herb Johnson]

> The TL866 device does fault checking rather quickly. No need to guess with
> in-circuit testing. 

Well, I don't "guess". I use, as I said, an oscilloscope if I have any 
doubts. I have the skills to consider, if a logic level is changing as 
it ought to; or if the signal suggests there's a pullup or pulldown 
problem. Likewise on outputs, if I get no change when I should get some 
changes. And: I can read the circuit logic if necessary, and determine 
what needs to be seen. This is what we old-people techs did in the era, 
with circuits of the era. It's still a useful vintage repair skill.

I don't trust a microcontroller, as in a TL866 device, to do much beyond 
some simple, slow logic-testing. It's go/nogo to be sure. And for quote 
"ten seconds work" on a $30 tester, I would not expect more.

But I'm not gonna test a box of loose chips, like some pick-and-place 
robot. I have all the 74LS00 chips I will ever need, without testing 
pulled ones. Their functions are easily determined, and they are very 
cheap.

I considered not posting the above. After all, it's about one set of 
skills versus another set of skills. People do what they are able to do, 
with tools they have.

But I posted, so those who use TL866 class testers can tell me "these 
are great, they do X Y and Z, really found subtle problems" and so on. 
Or not. I'd appreciate hearing about actual results. and: I don't hear 
much posting about "oscilloscopes" - they are surely out of common 
practice, but they are really useful in my opinion, and should be 
discussed in the matter of logic-chip-level vintage repairs.

One other thing.

These chips aren't going into any "parts bins" of unused chips, as 
suggested. Martin said "...into the VCF box ... long term storage". So 
no confusion, because they aren't "confused" with new chips anyway. 
That's a prudent decision, in my opinion. In my shop, old used parts and 
new parts are kept separate, for reasons already discussed.

Also: I haven't seen any accounting of the parts themselves. This may be 
a lot of fuss, over little.

I'll be curious to hear, what is actually found among these chips, what 
is usefully scarce versus all-too-common. A list in the "VCF box", keeps 
people from digging through just to find nothing desired. And now that I 
invested some interest in the matter, I'd like to see what came of it.

Regards, Herb Johnson


-- 
Herbert R. Johnson, New Jersey in the USA
http://www.retrotechnology.com OR .net
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