Use an O'scope to Bal DC

 


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Last Edited:
12-Sep-2004

 
This is the DC Balance Adjustment procedure for the 222C Integrated Stereo Amplifier, quoted directly from the H.H. Scott "Service Bulletin."

"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."

 

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