			August 15, 1979
HP-13 Series						Bulletin No:
DC Power Supplies						HP-13-1

		         Using HP-1144A as Bench Supply

When using the HP-1144A as a bench supply to check the  HP-13 series of
DC power supplies, the crowbar circuit in the  HP-1144A may cause the 20A
fuse to blow at turn-on.  This is due to high turn-on current of the 
HP-13 causing the  HP-1144A regulator circuit to compensate for sudden
output voltage drop.  This, in turn, causes an instantaneous voltage
increase to the crowbar circuit and causes the  20A fuse to blow.

So, when using the HP-1144A to test the HP-13's, disconnect the cathode
of the SCR Q4 to disable the crowbar circuit.

Be sure to reconnect the cathode lead to Q4 after servicing the HP-13.
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