09-15-2013, 10:21 AM
Well, here I go again. It looks like the most problems I have are some kind of hum and they're all different.
This one is a Zenith 79H20. After a recap, all tubes tested as well as resistors. AM sounds great. After an alignment FM pulls in many stations. Between stations there is a steady hum. To confuse me even more, when I touch the volume control shaft (using an isolation transformer) the hum gets a bit louder. I've checked all ground connections. Could I have missed a resistor or a mica cap?
This really is a great sounding radio. Any ideas?
:
http://www.nostalgiaair.org/PagesByModel...025312.pdf
This one is a Zenith 79H20. After a recap, all tubes tested as well as resistors. AM sounds great. After an alignment FM pulls in many stations. Between stations there is a steady hum. To confuse me even more, when I touch the volume control shaft (using an isolation transformer) the hum gets a bit louder. I've checked all ground connections. Could I have missed a resistor or a mica cap?
This really is a great sounding radio. Any ideas?
:http://www.nostalgiaair.org/PagesByModel...025312.pdf
Eric
Lake in the Hills, IL
Member: Philco Phorum, ARF, ARCI & Radiomuseum.org
