|
Check the voltage on the first grid (pin 7). This should be ZERO. Any positive
reading here indicates some leakage from the plate of the previous stage (through
a defective capacitor C14 or C19). Another thing to check is to make sure that
the speakers are connected to the correct taps as found when you got the set.
The present conditions are giving you about 8.5 W plate dissipation, while the
tubes are rated for 12, so I would say that if sound through the speakers is
acceptable, you could leave things as they stand, and just go around the
four audio tubes and measure all the specified voltages. This will give us a
global picture of the operating conditions of the audio stages. You might
also try substituting the brand new tubes (6AQ5s first, then 6AU6s) and see
what this does to the voltages. Worn tubes can do funny things...
Last edited by electroking; 07-13-2010 at 04:06 PM.
Reason: corrected spelling
|