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older power supply problems

Posted: Thu Oct 02, 2003 3:58 pm
by qdgjcl
I just got an older Power Designs Power Supply Model 6050A. When I turn it on the fault light flashes and when I check the output voltage with my meter I get nothing as I turn the voltage up. On the back of the unit it has some instructions and mentions the flashing fault light and something about over-voltage crowbar. Does anyone out there know anything about these power supplies?<p>Thanks<p>Brad

Re: older power supply problems

Posted: Fri Oct 03, 2003 10:28 am
by dacflyer
i'd have to see more of it to tell you for sure..
but a crowbar is basically a circuit that shorts the output of the supply to save your equiptment from being destroyed...<p>this could be because of over voltage or ac intruding into the dc...<p>they have this crowbar in peavy power amps also...
so that that no dc will fry your speakers..incase of a amp failure...the crowbar will kill the amp before your expencive speakers...some speakers cost more than the amp...especially when you get into them 18" ones,,,

Re: older power supply problems

Posted: Fri Oct 03, 2003 2:10 pm
by Dave Dixon
I think the manual is available at I hope this helps.
73's de Dave

Re: older power supply problems

Posted: Fri Oct 03, 2003 8:05 pm
by rshayes
Some lab power supplies had provision for remote sensing and/or remote programming. These usually had a barrier type of terminal strip on the back.

If the sense terminals are disconnected, there will be no feedback, and the output voltage will go to maximum. This would trip the overvoltage or crowbar circuit, which would then short circuit the output, holding the voltage close to zero. These circuits usually latch, and are reset by cycling the power off and back on.<p>Some power supplies were programmable by connecting an external resistor. The value of the resistor determined the value of the output voltage. If there is no resistor connected, the output would go to its maximum value and trip the crowbar circuit.<p>Operation with internal control may require jumpers on the terminal strip to connect the sense lines or to connect an internal programming resistor. Over the years, it is possible that these jumpers have been removed. There should be some instructions printed on the back panel if jumpers are required for normal operation.