| Author |
Message |
Dan Nicotera
Guest
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 Posted:
Wed Nov 09, 2005 5:42 am Post subject:
Hum in one channel only HF86 amp??? |
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I've rebuilt an EicoHF86 power amp and I am getting hum in the right channel
only!!
It has all new caps, resistors etc.
If you pull the 12dw7 on the channel that's humming, the hum goes away.
I have redone the heater wiring again, tried a different power transformer
for the ac heaters, swapped out the coupling caps...I'm running out of ideas
here to try.
The left channel is dead quiet, and I have less than 10mv of AC component in
the DC B+ for that driver/phase splitter tube. That rules out the power
supply.
The have the input shorted to ground.
Any other ideas???
Dan
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Boris Mohar
Guest
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| Posted:
Wed Nov 09, 2005 4:57 pm Post subject:
Re: Hum in one channel only HF86 amp??? |
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On Tue, 8 Nov 2005 21:56:12 -0500, "Dan Nicotera" <dnicoter@rogers.com>
wrote:
| Quote: | I've rebuilt an EicoHF86 power amp and I am getting hum in the right channel
only!!
It has all new caps, resistors etc.
If you pull the 12dw7 on the channel that's humming, the hum goes away.
I have redone the heater wiring again, tried a different power transformer
for the ac heaters, swapped out the coupling caps...I'm running out of ideas
here to try.
The left channel is dead quiet, and I have less than 10mv of AC component in
the DC B+ for that driver/phase splitter tube. That rules out the power
supply.
The have the input shorted to ground.
Any other ideas???
Dan
|
Heater to cathode leakage on that tube. Did you try swapping 12DW7?
Regards,
Boris Mohar
Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca
void _-void-_ in the obvious place |
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Dan Nicotera
Guest
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| Posted:
Thu Nov 10, 2005 3:42 am Post subject:
Re: Hum in one channel only HF86 amp??? |
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Yes I've tried swapping tubes.
It must be either picking up the 60 cycle in the first stage or it's a
ground loop of some kind!!
Dan
"Boris Mohar" <borism@sympatico.ca> wrote in message
news:pdl3n19jg03ra5kvo97j5rn3e8e1btlrbf@4ax.com...
| Quote: | On Tue, 8 Nov 2005 21:56:12 -0500, "Dan Nicotera" <dnicoter@rogers.com
wrote:
I've rebuilt an EicoHF86 power amp and I am getting hum in the right
channel
only!!
It has all new caps, resistors etc.
If you pull the 12dw7 on the channel that's humming, the hum goes away.
I have redone the heater wiring again, tried a different power transformer
for the ac heaters, swapped out the coupling caps...I'm running out of
ideas
here to try.
The left channel is dead quiet, and I have less than 10mv of AC component
in
the DC B+ for that driver/phase splitter tube. That rules out the power
supply.
The have the input shorted to ground.
Any other ideas???
Dan
Heater to cathode leakage on that tube. Did you try swapping 12DW7?
Regards,
Boris Mohar
Got Knock? - see:
Viatrack Printed Circuit Designs (among other things)
http://www.viatrack.ca
void _-void-_ in the obvious place
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