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Old 11-01-2011, 12:18 PM
bob91343 bob91343 is offline
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Join Date: Nov 2010
Posts: 745
No difference in hum while touching 6Q7 cap indicates a problem in the audio section. If there is a change when tuning, it seems the IF may be oscillating.

Check deeper for errors. This is why I never advocate a total recap - too many chances for error. Once it works, you can change a part at a time to make sure you aren't screwing up.

Check that the B+ is adequate. You'll need a voltmeter for that. See if the ripple is excessive; you will need a 'scope for that unless you have a spare electrolytic capacitor to parallel the existing one. If the hum goes away, you need to fix the power supply.

One sneaky way to check the B+ is to run the radio, pull the power plug, then quickly short the B+ to ground with a screwdriver. Should get a major spark.
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