Re: DC503 Not Working


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).

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