Bad channel in RCA Victor Console - diyAudio
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Old 8th April 2010, 01:24 AM   #1
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Default Bad channel in RCA Victor Console

I bought this old console at a thrift store for $20.
It has an awesome wooden cabinet. But the channel in the left was dead.
I brought it home many months ago, and I am working on it in the present.
The problem is in the amplifier chassis. I cut out the two capacitors and replaced them with new capacitors. The local shop didn't have the right ones so I put a few of them in paralel for each normal capacitor I replaced.

The unit had ports in the rear where you can hook on two external speakers, but for the people who done use them, these connections are bridged.

After the cap change, and fiddling with the connections, the left channel came back a little.

The right channel is rich and powerful, but the left is feable, and when I turn the bass up I get a flabby bass sound.

The two output tubes are 6BQ5 tubes for the Left and Right.

I tried switching them and no effect. I also sanded and tightened up the tube socket and tube pins. No help with my problem, but a good idea anyways.
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Old 9th April 2010, 01:32 AM   #2
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What could be wrong guys? I am dying to know why one channel is weak at best, and the other is strong and rich. Help!

I ran though the resisters, and I don't see any open ones.
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Old 9th April 2010, 01:46 AM   #3
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Are there any cathode bypass caps? Perhaps they've dried up,and the gain has dropped.
The caps you replaced,I assume were the power supply filter caps?
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Old 9th April 2010, 04:58 AM   #4
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Originally Posted by DigitalJunkie View Post
Are there any cathode bypass caps? Perhaps they've dried up,and the gain has dropped.
The caps you replaced,I assume were the power supply filter caps?
I'm totally frustrated. I'd ALLMOST like to throw it though the door of an audio repair store and let them fix it.

Just kidding.
No the caps are connected to the two output tubes. I tried testing all the resisters in the amp, and they are mostly spot on in values, and some are a little off. Nothing dramatic. Not enough to make the left channel weak.

When I turn the balance to the extreme left, and crank the volume way up, I can hear sound but it is tinny and lack any bass.

Last edited by CivicProtection; 9th April 2010 at 05:03 AM.
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Old 9th April 2010, 05:51 AM   #5
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Hello,

is the cathode capacitor properly connected? One bad solder joint and you have a strong feedback. Have you checked the voltages?

George
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Old 9th April 2010, 07:02 AM   #6
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Originally Posted by Gorgomat View Post
Hello,

is the cathode capacitor properly connected? One bad solder joint and you have a strong feedback. Have you checked the voltages?

George
I checked all the solder joints going to the left channel output tube.

I desoldered the new capacitor and put in the old wax one, no change. Then I put the new one back in. Could this be a bad left channel output transformer?
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Old 9th April 2010, 07:16 AM   #7
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Have you checked the winding dc resistance with a multimeter?
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Old 9th April 2010, 07:18 AM   #8
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Originally Posted by CivicProtection View Post
I checked all the solder joints going to the left channel output tube.

I desoldered the new capacitor and put in the old wax one, no change. Then I put the new one back in. Could this be a bad left channel output transformer?
I take it you don't have any test equipment? A scope and signal generator would make short work of it. The transformer _could_ be bad but I've never heard of one failing - however I don't know of many tube amps compared to the number of SS amps. It wouldn't take a lot of time to swap the transformer electrically and verify it's good/bad. I would bet a small amount that the transformers are OK.

G
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Old 9th April 2010, 07:59 AM   #9
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Originally Posted by stratus46 View Post
I take it you don't have any test equipment?
I have a digital multimeter.
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Old 9th April 2010, 11:32 PM   #10
jjman is offline jjman  United States
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You're testing with external speakers, yes?
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