Webcor Holiday Coronet record player

Agellius

Agellius

Active Member
I just bought this thing from an antique store, I just wanted something to play 78s on. It's apparently 1950s vintage. I tried it out in the store and it sounded good and the mechanism and all the controls seemed to work.

But when I got it home and played a record there was this loud bass hum. I didn't notice any hum at all in the store. Records play and they sound fine. There's just this hum.

Anyway it's an as-is sale of course. Being totally new to tube equipment I was wondering if anyone could give me a clue where to start looking for the cause of the hum. Would changing out some or all of the tubes be a good place to start?

Any info would be much appreciated. Thanks.
 
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First step - pull the plug from the wall and flip it 180*. If that doesn't fix it...someone will come along with some good advice.
 
Some tube amps have a potentiometer for hum control. If it's there, it will be a knob or rotatable shaft marked "hum." However, I'm going to guess that you have a capacitor or resistor way out of spec, most likely a cap.
 
More than likely the selinium rectifier and filtering caps have gone bad. If you intend to really use it, replace all electrolyic caps, replace the rectifier (tube and/or selinium), check values on the carbon resistors and replace whatever is off and then give 'er a spin. If it's had a lot of play, the input and output tubes may need replacing as well. Check the insulation on the power cord and replace if cracked.
 
Thanks for all the suggestions. I'm going to try them insofar as I understand them. Thankfully it's a very simple-looking setup compared with later solid-state units.

One more thing in case it helps with the diagnosis: The hum is constant -- it doesn't change when you turn the volume up and down but stays the same all the time.

Also, does the fact that there was no hum in the store, but there was hum when I got it home, indicate anything in particular? Is there something that could have got jarred on the ride home, resulting in hum?

Thanks again.
 
If I was to guess, by the time you got home and fired her up again, the filtering caps gave up the ghost. After re-capping, it will play stronger and be quieter. Don't dismiss what I said about suspect resistors though. Those suckers can be real noisy.
 
I have now done the following:

1. replaced the rectifier tube

2. replaced all electrolytic caps

3. tested all the resistors -- only one was out of spec and I replaced it

4. replaced the power cord

The only other thing I can think of that is within my competence is replacing the remaining tubes, of which there are three more: two 35C5's and a 12AX7.

Will that be a waste of time most likely? Is there another suggestion that sounds more likely?

I have a Photofact "service manual" with a schematic, but I can't claim to be able to read schematics. I have been told that it could be a faulty ground but I just don't know how to check that. Would it help if I scanned and posted the schematic?

Thanks again for any help.
 
Those tubes really are rarely bad. Plus many Webcors are re-branded Mullards and very highly sought. That 12AX7 alone could be worth close to or more than you paid for the entire unit. :yes:
 
Andyman:

That's good to hear. I bought it mainly just to have something to play 78s on. I admit I was suprised how good it sounds despite the hum, I never knew 78s could put out such nice, clear sound.
 
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