POWER SUPPLY MALFUNCTION

[N9LCD]

I set-up my HP 6267B power supply to run my Icom IC-271A. I set output voltage at 14.00 volts and then set the crowbar voltage at approximately 15.00 volts. Output current was set at "maximum"; I wasn't running the supply in a constant current mode.

I checked the voltage with a DVM at the end of the power cable, 13.81 volts -- consistent with the 14.00 volt output.

BUT when I connected the -271A and turned on the power, the 6267B's output voltage shot up past 18 volts, until the crowbar tripped.

QUESTION: I've heard of and seen power supply output voltage drop under load because of poor regulation or defective components. But I never heard of a power supply's output voltage INCREASING under load. Does anybody have any suggestions what the problem could be?

NOTES:

HP 6267B specifications: 0 - 40 volts and 0 -10 amps output.

IC-271A specifications: 13.8 volts, 1.4 amps - receive with maximum audio output.

Thanks!

Jerry -- N9LCD

[N9LCD]

I tested the 6267B under load using a couple of 12-volt, 50 watt "marine" light bulbs as a dummy load.

Set the output voltage for 12 volts on the supply's volt meter. Rechecked it with my DVM, still 12 volts. Screwed in one light bulb. The output voltage shot-up to about 20.6 volts. So did the output voltage on the DVM. Current on the supply's ammeter was about 4.5 amps.

Shut her down fast!

Whatever the problem is, it isn't covered in the trouble shooting section of HP manual.

Oh well, Streets & San got two defective 6267B's to haul away next week.

N9LCD

[kd8geh]

Its a constant voltage and current sensing supply like mine. I think you may have a failed sensing resistor in the circuit. Look for the shunt in the schematic. Hope this might helps. Doesnt sound too bad.

73 and Good Luck

Dave