On Mon, Jan 23, 2017 at 11:38 PM, Adrian Graham <wit...@binarydinosaurs.co.uk> wrote: > On 23/01/2017 21:38, "Tony Duell" <ard.p850...@gmail.com> wrote:
>> Oh... The trace isn't open-circuit, is it? Check it with the >> multimeter. Given the >> corrosion damage to the tape drive I could well believe PCB problems of a >> similar nature. > > I've measured resistance from all points to all points, there's 9: > > 74LS373 (output, new socket checked for solder bridges, new chip) > 4x 2764 EPROM (new chips, no new sockets yet) > MC3242A (new chip, no new socket yet, this one had bad verdigris) > 74LS139 > 74LS21 > 74LS365 > > and it's 0.6ohm max. Are you telling me that if you put 2 logic analyser inputs on 2 points on the same trace (which tests as continuous with an ohmmeter) that said 2 LA channels don't show the same thing? If so, the LA needs repairing! Given the problems I've had with even clean old sockets, I would have replaced those. Corroded sockets must be worse. And I can't believe they used turned-pin sockets in something like this. -tony
