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Old 08-10-2011, 12:55 PM
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miniman82 miniman82 is offline
First Light: 1952-2011
 
Join Date: Jun 2009
Location: Great Mills, MD
Posts: 4,174
21-CT-55 power supply failure

The other day I installed the last of the new caps into the '55, so it's a good reliable runner now... or so I thought.

A couple seconds after it came on, the picture got all fuzzy with hum bars slowly drifting up the image. Voltage checks revealed B+ was 360 when it should be 400, and there's 36VAC of hum now. I suspected one of the new filters I installed might have bit the dust since they are only 80uf when they should be 200 (doubler circuit), but replacing them didn't fix it. I suspect the seleniums might have gone bad, so I'm going to replace them with new diodes. Trouble is new silicon outputs more voltage, so I need to know what value resistor to use. I could always just run the variac, but I don't want lower filament supplies. Can anyone with a CT55 tell me what they have done with the power supply?
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