DECstation 220 - Out of Ideas?

Rob Jarratt robert.jarratt at
Wed Jun 28 01:22:49 CDT 2017

I removed the 74LS125 and tested the resistance of the board connections with it out of circuit, the suspiciously low resistances remain. So either there is a fault somewhere else, or it really was designed to be like this and the cause of the signal not going low enough is something else.

I have found following the traces on a two-sides board like this with tracks that are relatively small and relatively densely packed to be awkward. Are there any clever tricks or is it simply a matter of laboriously turning the board over lots of times and trying to work out where the vias on one side come out on the other side?



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