Thunder 1 RVT project, half power from rectifier tube

Danohss

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Working on a Thunder 1 RVT, only getting 180 volts out of the rectifier tube, it's a brand new JJ. Any ideas? Line voltage going in is 120 to 130, did a downstream cap job but none of that work should effect the rectifier output voltage. Dropped the old Guild r drifter tube on the concrete, no way to put the old one back in now to check it. Can't imagine a brand new JJ would be the problem anyhow. Someone before me has replaced the 47 ifs electrolytic that connects to pin 3, looks fine, grounds all check out good. Hum pot has no effect on volts out. Any ideas or guidance would be greatly appreciated.
 

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Working on a Thunder 1 RVT, only getting 180 volts out of the rectifier tube, it's a brand new JJ. Any ideas? Line voltage going in is 120 to 130, did a downstream cap job but none of that work should effect the rectifier output voltage. Dropped the old Guild r drifter tube on the concrete, no way to put the old one back in now to check it. Can't imagine a brand new JJ would be the problem anyhow. Someone before me has replaced the 47 ifs electrolytic that connects to pin 3, looks fine, grounds all check out good. Hum pot has no effect on volts out. Any ideas or guidance would be greatly appreciated.

Check ac voltage on pins 1 and 7, then dc voltage on pin 3. you should be getting about 350-360 DCV according to the schematic.
Might be a bad recto, even if it's new. Might be a dead winding on the pt.
 

Danohss

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I have 350 volts AC coming out of the transformer to the rectifier, and heater volts are 3.6 VAC.
 

Danohss

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Any chance that 47 ufd cap ( schematic shows a 50 ufd) could be the culprit? looks to be very new, doesn't show any dc volts leaking through.
 

Danohss

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Nope, it's 3.3 volts on the heaters, probably the root of the problem but I can't figure out why the heaters are low.
 

Danohss

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Put this amp away for awhile, now it's back on the bench and I'm still scratching my head. Wondering if the hum balance pot could be bad, keeping heater volts low, halving the output of the tube?
 

JohnW63

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I wish I had a schematic to follow along with this conversation. I had some years of electronic classes in college, but have been in IT ever since.
 
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