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Old 6th January 2011, 08:56 PM   #1
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Default HeathKit Euw-15 Tube power Supply failure.

Hey guys I just bought a Heathkit Euw-15 power supply from ebay, and the first time I powered her up, and used my DC volt meter to test her she was working just fine.

She is rated to about 350V when operating in HIGH DC mode.

Basically there are two switches one saying AC and the other High Power DC.

You flip them both on. However now when it is in the voltage regulation mode, it is putting out 520V!

THe voltage regulator potentiometer does nothing to change the voltage.

I tested the pot to see if its malfunctioning, and its not.

When I test the pot between the wiper and the outer blade it goes from 0 ohms to 100k as it should since it is a 100k lin pot.

But what I dont understand is how it could go from producing 350V max on the same DC line to 520V!

The capacitors are rated from 350V so I cant even run it for that long or at all. I dont want to damage the capacitors, everything is vintage.

Thanks help would be appreciated.
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Old 6th January 2011, 09:16 PM   #2
llwhtt is offline llwhtt  United States
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What you are seeing is probably the raw supply, the pass elements (tube or transistor?) are full on or shorted. Could be them or what's controlling them. I have one piece from the EUW series and the only place I could find the service manual was from Don Peterson at Data Professionals, did you get any literature with the unit?

Craig
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Old 6th January 2011, 10:51 PM   #3
kmtang is offline kmtang  Canada
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Download the schematic and check it out.

http://www.tech-systems-labs.com/schematic/EUW15.pdf

JOhnny
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Old 6th January 2011, 11:51 PM   #4
llwhtt is offline llwhtt  United States
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After looking at the schematic, where are you taking your readings from? If from gnd to +DC you'll need to strap the - and gnd together. If from - to + you should see what you are expecting if it's working properly.

Craig
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