On Tue, Jul 28, 2020 at 12:39 AM, <email@example.com> wrote:
I finally printed the manual out and figured out what scan clock disable (pin
6) is. It is an input from the backplane connector (pin 27A). This should not
be low resistance to ground, either on the DC503 or on the backplane. It
probably won't be, however. I suspect that since there seems to be some
intermittancy involved, that something is marginally disrupting the
multivibrator. Check the driven circuits as Roger suggested. Otherwise
suspicion returns to the multivibrator, itself. Resolder all the connections,
clean the socket and IC pins carefully and, possibly for good measure, replace
the capacitors (I know they look OK DC wise).
I will do and check all what you guys very kindly suggested, and report back as soon as it’s done.
I will replace those two 0.1uF capacitors for good measure. All I have readily available at the moment are rated at 600V instead of the 100V the schematic calls for. Overkill and way much bigger as you can imagine, but that’s all I have. Will try to make them fit as the top board needs to sit on top without shorting them.