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Author Topic: Kenwood PS-30 Power Supply Excessive Voltage Issue  (Read 12798 times)
K8AXW
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« Reply #15 on: May 16, 2012, 09:05:53 AM »

You seem to have found your problem.  Congrats!  However, the NL 16 volts is too high.  Can you adjust it down to 13.8VDC?  If so, then you have the first part solved. 

The second part is to load the power supply and see how your regulator controls the voltage.
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KA4POL
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« Reply #16 on: May 16, 2012, 10:25:35 AM »

Good to hear this. It is always difficult to make a remote diagnosis. The 16V output could well be from your previous trials to adjust it. Let us know if you could get the adjustment to make the output close to specs.
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ZS1SA
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« Reply #17 on: October 23, 2017, 07:08:38 AM »

I had the same 22 volt issue with one that I picked up. The problem was a faulty Q1 transistor which is a 2SC733.
I didn't have one of these in my junk box so I stuck in a general purpose 2N2222 PNP transistor and the supply now works properly. Note that the pin out for the 2N2222 is different from the original transistor so you will need to twist the leads around differently to get the proper connections in the PC board.
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WB0CJB
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« Reply #18 on: October 23, 2017, 07:31:06 PM »

With a load on the power supply the voltage will drop to 13.8 volts or so. I recently repaired a a PS-30 and confirmed its correct voltage using my TS-120S as the load. The power supply worked perfectly.

WB0CJB
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K8AXW
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« Reply #19 on: October 24, 2017, 09:44:02 AM »

Quote
With a load on the power supply the voltage will drop to 13.8 volts or so.

A regulated power supply is supposed to maintain it's set voltage throughout it's rated current!  (The voltage MAY drop a volt or so but no more)

To operate a piece of gear at 16 volts is asking for big time trouble. If the gear pulls the voltage down to 13.8VDC under load; then it's reasonable to assume that the voltage will continue down as the load increases.  This is not the characteristic of a regulated supply.

Set the voltage to 13.8VDC and put your load on it.  If the voltage sags then you either have the power supply overloaded or the regulator isn't working properly.
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KA5IPF
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« Reply #20 on: October 24, 2017, 07:16:51 PM »

The design of the PS-30 allows it to float to abt 16v with no load. Any load, even a 1k resistor will drop it to 13.8. I never tried to figure it out but that's the way it works.
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K8AXW
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« Reply #21 on: October 24, 2017, 09:17:24 PM »

Clif:  OK, I stand corrected!  This is good information to know because now I'll never consider buying a pizza sheet like the PS-30!  I own a Kenwood KPS-7A and it has basically the same regulator as the Astron power supplies.  I ASS-U-ME'd they would just adjust components for higher power as Astron does. 
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KM1H
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« Reply #22 on: October 25, 2017, 06:59:05 AM »

Im not a fan of NTE parts especially when regular versions are regularly available and usually cheaper.

For 9.1V zeners the 1N4739A is 1W at .25 from Mouser and the 5W 1N5346A is .47.

Ive been replacing all my 1W zeners with 5W as I run out and buy either 10 or 100 at a time depending upon "popularity" as common failure parts.

Carl
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