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Zenith g725 (7G01)
2/19/2009 12:38:04 PMRobert Steiner
I have replaced all the wax caps ,all the electrolytics and replaced the selenium rectifier with a 1n5408 3a 1000v diode. the original wire wound res was a 10ohm 5 watt. I replaced it with a 68ohm 10 watt wire wound. At 120vac ,I have 124vdc at the 80uf electrolytic cap after the diode.What other voltages should I read at the other lytics. The radio has been running for a half hour now, Am sounds great picks up all stations. Fm sounds good ,picks up all stations good volume.some stations a slight distortion............Rob
2/19/2009 5:01:05 PMDoug Criner
Schematic: http://www.nostalgiaair.org/PagesByModel/537/M0025537.pdf

The schematic is calling for 130V where you measure 124V, so it looks like you're a bit low.

But rather than home-in on the voltages at the e-caps, better to go by the plate voltages, which are given for each tube. Those are the pay-off numbers.
Doug

2/20/2009 8:48:52 AMRobert Steiner
I changed the 68ohm wirewound res. to 50ohms and have 130.5 vdc. all the pin voltages are right on or within 1 or 2 volts. the radio sounds better. thanks ...Rob Schematic: http://www.nostalgiaair.org/PagesByModel/537/M0025537.pdf
:
:The schematic is calling for 130V where you measure 124V, so it looks like you're a bit low.
:
:But rather than home-in on the voltages at the e-caps, better to go by the plate voltages, which are given for each tube. Those are the pay-off numbers.
:Doug
:


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