Gibson Les Paul TV model

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UFO Builder
Junior tube assistant
Posts: 6
(1/31/04 9:59 am)
 Gibson Les Paul TV model
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 Hi, I just replaced the power transformer in an old 1957 Gibson amp. The circuit used is basically an early Champ layout, using 5Y3, 6V6 and 6SJ7 tubes. The replacement pt I used was physically the same size, with these specs: 325-0-325 @ 40mv, 6.3V @ 2A, 5V @ 2A. The problem I'm having is that the transformer seems to run too hot. The other day, I stuck a temp sender from an indoor-outdoor digital thermometer to it, and let it idle for an hour with all tubes in. The temp rose to about 140F in that time, and still seemed to be going up, although slowly. Right now it's idling with the 5Y3 out of the circuit, and the temp is only 95F. My question is this... would it help to install a rectifier tube with lower heater current demands than the 5Y3? What tube would work for this? Thanks in advance for any advice.
 
Tiny Daddy
I will work on all amps
Posts: 466
(1/31/04 11:45 am)
 Re: Gibson Les Paul TV model
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 140F is not too hot, my attic gets that hot in the summer. It may feel hot to your hand because anything much over 98.6 degrees feels too hot. 5AR4 draws slightly less filament current than 5Y3.
 
UFO Builder
Junior tube assistant
Posts: 7
(1/31/04 8:42 pm)
 Re: Gibson Les Paul TV model
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 I'll try leaving it on longer while playing through it and check the temp again. I just want to avoid frying my transformer.
To add to the info above, I replaced the filter caps and any other caps and resistors that were out of spec too far. It still has the original 10" speaker, and according to one Gibson amp website, the amp has an output of 3 watts.
A couple more questions... how much current does a 5Y3 tube heater filament normally require? And, is the HV winding of my pt (at 40mv) big enough to power this type of circuit?
 
Tiny Daddy
I will work on all amps
Posts: 466
(2/1/04 9:49 am)
 Re: Gibson Les Paul TV model
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 That transformer should work just fine in that amp. 5Y3 draws 2 amps of filament current.
 
UFO Builder
Junior tube assistant
Posts: 8
(2/2/04 4:56 pm)
 Re: Gibson Les Paul TV model
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 Thanks Tiny. The amp is working great and I've gotten past *The Fear* of frying it!
 
Jonas Gemini
Hey get your own solder
Posts: 287
(2/2/04 8:12 pm)
 Re: Gibson Les Paul TV model
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 UFO,

I am curious as to what is your B+ with the new tranny and the 5Y3? Thanks

Jonas
 
UFO Builder
Junior tube assistant
Posts: 8
(2/3/04 10:26 am)
 Re: Gibson Les Paul TV model
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 B+ voltage is 358V, measured at pin 4 of the 6V6 tube.
 
 
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