very hot power supply resistors

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covil
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very hot power supply resistors

Post by covil » Tue Oct 04, 2016 5:53 pm

I have a jcm800 homebuilt, with two very hot dropping resistors 10k + 4k7 in series and a ugly but subtle distortion over the notes. It´s the resistors before PI node. Already, tried changing all 12ax7 and changed all electrolytic caps, but nothing changed. Checked plate resistors and mesured ok. I suspect something is drawing too much current near that node. But what? I think that when i find the culprit it may solve the ugly distortion.
Any tips? Is it normal for such high temperature on that rc?
Ps: The amp played fine for more than ten years.
best regards, Jorge.

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neikeel
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Re: very hot power supply resistors

Post by neikeel » Wed Oct 05, 2016 3:47 pm

Is the PI filter cap drawing too much current?
Neil

covil
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Re: very hot power supply resistors

Post by covil » Thu Oct 06, 2016 4:35 pm

second thing i´ve tried. First tried another 12ax7, second changed supply cap. It´s not a new cap but both pass on multimeter test( don´t own an ESR meter).
Last edited by covil on Thu Oct 06, 2016 4:38 pm, edited 1 time in total.

covil
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Re: very hot power supply resistors

Post by covil » Thu Oct 06, 2016 4:37 pm

If it´s a short on another node downstream or faulty cap , it should be that node resistor that overheat , yes?

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neikeel
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Re: very hot power supply resistors

Post by neikeel » Fri Oct 07, 2016 12:21 pm

covil wrote:If it´s a short on another node downstream or faulty cap , it should be that node resistor that overheat , yes?
Yes
Neil

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