Bench Power Supply Issue

Thread Starter

Best_Intentions

Joined Jun 13, 2016
10
I have a Arksen DC Bench Power supply. The model is a 303D and is rated to 30 volts at 5 amps. This has worked fine for me until recently when it stopped allowing more than 9.1 volts to display on the voltmeter readout. The current is still fully adjustable and my multimeter confirms the voltage limitation of the supply. Does anyone have an idea of why this might be happening? I am not afraid of digging into the device to see if I can resolve it but I thought would get opinions on if I am wasting my time, etc. I am also prepared to buy a new supply and would also appreciate any recommendations of brands you might have experience with that have have provided good reliability. Thanks for any information provided.
 

SLK001

Joined Nov 29, 2011
1,532
Can you get 5 amps at 5 volts? Is the voltage 100% variable below 9 volts?

It sounds to me that one of your pots has gone bad.
 
I had a power supply once with a similar symptom. That supply had a bunch of transistors in parallel. Somebody who repaired it before didn't put the right transistors in. They stressed (when I stressed the supply) and would not allow it to go above a certain voltage, I think.

Take a quick photo of the inside and see if you can find a schematic. Many supplies were 723 regulator based. See what major IC part numbers you can find inside.
 

Thread Starter

Best_Intentions

Joined Jun 13, 2016
10
Thanks very much for all the replies. I do not have a ready schematic of this device unless there is a small one plastered to the inside of the cover which I have not yet removed. I have a laser printer to repair first but after that I will proceed to inspect the interior and try out your suggestions. Your help is appreciated.
 
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