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Old 02-06-2017, 08:45 AM
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Electronic M Electronic M is offline
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Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,762
I think you are right about the B+ secondary being the issue...You can confirm it by connecting a DMM in 500 VAC mode to the center tap of the B+ winding and metering both plates with the power on...One probably is getting zilch voltage.

Really all you need to do is replace the B+ winding. If you've been able to measure the voltage to one of the plates from the original then you can try somethings....Get a variac and see how close to line voltage you can get your donor trans before it matches the output of the original and then see what B+ is with both 80 plates getting AC adjust for proper DC and see what the variac is set at. If you have the variac only up at %40 of line voltage then you could try disconnecting the line winding of the new trans and connect the heater winding of the new trans to the 2.5V heater winding of the original transformer.

Basically if you keep the original trans and want to use a new one you can juggle where you connect the new one and what windings you use to get the correct voltage step up ratio with respect to the line voltage....I've done stuff like this with newer sets. When you find something that works I'd recommend taking the temp of both transformers every 10min on the first power up then every half hour for 1-3 hours of run time to make sure the new config does not cause overheating. If nothing overheats your golden.
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