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Topic: Dickerson amp problem |
Marc Weller
From:
Upland, Ca. 91784
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Posted 13 Oct 2005 5:16 pm |
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I have a pre war Dickerson amp which sounds great for about the first 20 minutes of play then begins to distort. It makes no unpleasant noises, has terrific tone until it gets hot. Seems to have the original tubes, they are not glass, but rather bakelite or some similar appearing plastic. Any suggestions?
MW
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Alan Kirk
From:
Scotia, CA, USA
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Posted 14 Oct 2005 4:25 am
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There is a product called "Circuit Cooler" or "Freeze Spray" that is used to cool individual components when troubleshooting a problem that occurs only after warm up. Not sure if you can use it on older, high-voltage amps. Someone else will chime in on that.
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Jack Stoner
From:
Kansas City, MO
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Posted 14 Oct 2005 5:49 am
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With the age of the unit, it can and most likely is (1) tubes and (2) power supply.
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Jay Fagerlie
From:
Lotus, California, USA
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Posted 14 Oct 2005 6:24 am
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Hi Marc,
Jack is on the right path....
In these old amps (I have one also) one thing to check is the bypass cap on the bias resistor for the output tube. Some companies had a habit of mounting the cap right next to the cathode bias resistor and the hot resistor has an effect on that cap.
If you are handy with a voltmeter, monitor the bias voltage at the cathode and see if it changes as it warms up, same with the B+ supply. If bother of these voltages stay pretty constant, I'd try the tubes....BTW the B+ voltage will be very high (be carefull!!!) and the bias voltage will be very low.
Jay |
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Keith Cordell
From:
San Diego
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Posted 15 Oct 2005 6:44 pm
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| Aw, it's not fixable... just send it to me for a proper burial... |
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