Piggybacking 74LS logic chips to confirm a suspected fault
hp-fix at xs4all.nl
Tue Dec 22 15:09:38 CST 2015
> -----Oorspronkelijk bericht-----
> Van: cctalk [mailto:cctalk-bounces at classiccmp.org] Namens Terry Stewart
> Verzonden: dinsdag 22 december 2015 21:50
> Aan: General Discussion: On-Topic and Off-Topic Posts
> Onderwerp: Piggybacking 74LS logic chips to confirm a suspected fault
> I've written up my recent third Apple II repair, this time an Apple IIe.
> One interesting aspect of this repair is that piggy-backing a logic chip helped
> confirm a faulty one. I'd only ever used this technique with RAM.
> I'm sure it only works if the chip has a particular type of fault, but it worked this
> time for me.
> Terry (Tez)
I use a HP 10529A logic comparator on regular basis for fault finding in ttl circuits.
It compares a reference chip with the CUT (Chip under test;) it's a very nice diagnostic tool.
It's a bit like piggy backing just a little more sophisticated :0
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