[rsfphil]

I'm going to replace the power tubes on my Scott LK72-B and was told I have to adjust the bias and the DC balance. I know how to adjust the bias, but I have no idea how to adjust the DC balance. Can anyone out there help me? Any help will be greatly appreciated. Thanks.

[Hank]

I just tried to log onto the HH Scott forum area that has user manuals, but I could not access it.  I tried to email the forum's founder and the email was returned.  I'm wondering if that great site is not being monitored now.
Anyone know?

[JohnR]

Schematic is here: http://www.freeinfosociety.com/electronics/schematics/audio/pictures/hhscottlk72b.jpg

[Scott F.]

What follows is part of an old thread over at the HH Scott website. I cut and pasted it into a Word doc years ago when I was rebuilding an old 299 (that I never finished  ).


Below is the actual H. H. Scott suggested DC Bias Balance procedure

"Equipment Needed - Oscilloscope and/or AC VTVM, 16-ohm resistive load of
adequate wattage (some wirewound resistors have considerable residual
inductance and these should be avoided).

The DC balance pot for each output stage is located between the output tubes
for that (respective) stage. These controls should be adjusted when the
output tubes age appreciably or are replaced. To set these controls use the
following procedure:

(a) Connect the 16-ohm resistor across the (speaker) output terminals of
the channel under test.

(b) Connect the oscilloscope and/or AC VTVM across the resistor, and turn
the horizontal selector of the scope to "LINE."

(c) Remove the phase/inverter tube (6U8/6GH8) of the output stage under
test.

(d) Adjust the proper DC Balance Control for a minimum 120 cycle response
on the scope or minimum reading on the AC VTVM.

(e) Repeat the entire procedure for the other amplifier stage."

Hope that helps