>It works if the gate is open. But if it is shorted to gnd/vcc, you're in >trouble :)
Yea. In my case the chip was quite cool, so I figured it wasn't shorted and took the risk. On reflection checking vcc/gnd with a multimeter would be a more definitive way of checking for a short of that nature. Tez On Wed, Dec 23, 2015 at 10:10 AM, Alexandre Souza < alexandre.tabaj...@gmail.com> wrote: > It works if the gate is open. But if it is shorted to gnd/vcc, you're in > trouble :) > > Enviado do meu Tele-Movel > Em 22/12/2015 19:09, "Rik Bos" <hp-...@xs4all.nl> escreveu: > > > > > > > > -----Oorspronkelijk bericht----- > > > Van: cctalk [mailto:cctalk-boun...@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 > > > > > > Hi, > > > > > > I've written up my recent third Apple II repair, this time an Apple > IIe. > > > > > > http://www.classic-computers.org.nz/blog/2015-12-22-appleiIIe-no-video.htm > > > > > > 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 > > > > -Rik > > > > >
