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Old 07-13-2010, 05:02 PM
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VintagePC VintagePC is offline
Tube bug got me 05/2010
 
Join Date: May 2010
Posts: 535
No difference with the tube changes... so I think that if we're within operating specs, I have myself a working set... I should note that there's some speaker hum when I measure the voltages on pin 7... I assume that's normal, since the meter is tying the pin to chassis ground.

Edit: I did find that changing the function switch to BC (as said on the schematic) lowers the voltage to about 14V... within the 20% tolerance.

However, I checked some of the other voltages. Pin 6 of the 6AQ5 should have 230V, but there is 265. Also, the 42V and 56V on the 6AU6s actually measure at about 10 and 20V. Wierd.

I doubt it's the cause, but I did note on the schematic that R35 (filter section of power in) masures only 228K as opposed to 270K.

Last edited by VintagePC; 07-13-2010 at 05:32 PM.
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