#26 pre amp
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 21st March 2013, 06:43 PM #2791 stajo   diyAudio Member   Join Date: Jun 2011 Location: Stockholm Cool. Your circuit looks like its working, at least the left. Right channel takes way to less current if measures are correct. Check grid leak there again, viltage between grid pin and kathode pin. How much does 15/20k drop?
merlin el mago
diyAudio Member

Join Date: Sep 2009
Location: Catalonia - Europe
Quote:
 Originally Posted by ikoflexer Your right channel idle current is 1.8mA? Either something is wrong with the circuit, or the tube is old. Exchange tubes between and measure again. Also, show the measured voltage between grid and ground.
How do you calculate 10R:9,79V? voltage gri to ground 0,001V

Last edited by merlin el mago; 21st March 2013 at 06:57 PM.

merlin el mago
diyAudio Member

Join Date: Sep 2009
Location: Catalonia - Europe
Quote:
 Originally Posted by massimo Sursum corda Pope Francis would say.... (Lift up your hearts)
Habemus 26

merlin el mago
diyAudio Member

Join Date: Sep 2009
Location: Catalonia - Europe
Quote:
 Originally Posted by stajo Cool. Your circuit looks like its working, at least the left. Right channel takes way to less current if measures are correct. Check grid leak there again, viltage between grid pin and kathode pin. How much does 15/20k drop?
DVM plus lead grid pin to DVM minus lead to cathode pin -9,6V

Last edited by merlin el mago; 21st March 2013 at 07:02 PM.

 21st March 2013, 06:59 PM #2795 massimo   diyAudio Member   Join Date: Dec 2002 Location: Milan, Italy Habemus XXVI
 21st March 2013, 07:02 PM #2796 merlin el mago diyAudio Member     Join Date: Sep 2009 Location: Catalonia - Europe Oooops I forgot roman numbers.
stajo
diyAudio Member

Join Date: Jun 2011
Location: Stockholm
Quote:
 Originally Posted by merlin el mago DVM plus lead grid pin to DVM minus lead to cathode pin -9,6V
Then cathode is positive to ground (and now grid also), as it should be. Slow down now. Look, measure and maybe listen to your circuit.

 21st March 2013, 07:07 PM #2798 merlin el mago diyAudio Member     Join Date: Sep 2009 Location: Catalonia - Europe So can't change the right channel tube as Iko suggested?
merlin el mago
diyAudio Member

Join Date: Sep 2009
Location: Catalonia - Europe
Quote:
 Originally Posted by stajo Cool. Your circuit looks like its working, at least the left. Right channel takes way to less current if measures are correct. Check grid leak there again, viltage between grid pin and kathode pin. How much does 15/20k drop?
20K drops 92,5V
15K drops 96,1V

 21st March 2013, 07:17 PM #2800 iko   diyAudio Moderator     Join Date: May 2008 Location: Toronto If you take the tube from the left channel and put it in the right channel, and if you still measure 0.18V across the 100R resistor, then the problem is not an old tube in the right channel.

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