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Old 5th November 2006, 04:05 PM   #1
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Default sparking Output transformer In Webcor 14x240 Amp

i was given a Webcor Holiday Coronet Record player a whilst back...
and scince the turntable is mechanically busted... id like to use it as a gituar amp...
i know this thing Need's a Iso transformer So i dont fry my ****..
but ive noticed that there seems to be an arcing inside the opt
(i temporayly wired up a diffrent turntable)
iat first it had a nice warm sound... then it would start to pop during playback... i did a visual insp... nothing... then i turned it on and put my ear up to the opt... Yes Its arcing inside
any hope? if not i could try to put something else there...

btw the tubes

rectofier is a 35w4
preamp seems to be a push pull it has a pair of 35c5
and the power amp is a 12ax7

id also like to know if i could use a
12at7 or
12av7 or
12au7
in place of the 12ax7
and while im at it ill ask if use my guitar is there any possible way to overdrive it safely...

sorry i dont have a schematic but here are some pics

[IMG]Click the image to open in full size.[/IMG]
[IMG]Click the image to open in full size.[/IMG]
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Old 5th November 2006, 06:01 PM   #2
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Well, if you can hear the transformer arcing, then it's definitely bad and will need replacing. And I would stick with the 12AX7. While the others you mentioned are similar in pin-out and filament current, they will provide less gain.

Victor
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Old 6th November 2006, 04:33 PM   #3
kevinkr is offline kevinkr  United States
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Sounds like the output transformer is bad, this problem can be the consequence of running it without a load (speaker) connected. Make sure that this can't happen after your replace the transformer. (Some inexpensive Hammond or Edcor ought to be suitable. I suspect something with an ~8K primary might be ok.)

This is a fairly dangerous amplifier to use for guitar, never use it without an isolation transformer as the chassis could be hot depending on the orientation of the line cord.

Note as well that you should probably replace the electrolytic caps in the power supply as well as the coupling capacitors.

You will want to stick with a 12AX7 in order to have enough gain for use with your guitar.
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