[time-nuts] HP 5370A A22 arming assembly circuit diagram error

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Wed Oct 25 18:47:17 EDT 2006


The positive supply connection to A22:U7 (LM339 quad comparator) is 
shown as ground in the circuit diagram.
This is surely incorrect as the inputs of U6B and U6C are connected to 
TTL(+5V VCC) signals.

Surely this is not the designers intention
The positive supply of A22:U7 should be +5V.

Is there a manual change correcting this schematic error that I have missed?

If A22:U7 positive supply is indeed ground, the circuit may still work 
but its reliability will be compromised by the relatively large currents 
flowing into A22:U7C&D input substrate diodes.

Bruce




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