Fisher KX200 d'Arsonval meter adjustments

[Glensound]

A friend of mine has just resurrected his KX200 amp and was wondering about the balance / bias meter adjustments. Does anyone know what the optimum settings will be and how to adjust the d'Arsonval meter?

 

[dcgillespie]

Other than the zero adjustment on the meter itself, it is the 390 Ohm resistor that calibrates the meter to the correct setting. However, that calibration is very hard on the output tubes. I recommend lowering it to 240 Ohms, which will then cause each tube to operate at a quiescent current of 35 ma when adjusted to the set line, assuming that the meter itself is operating properly.

Dave

 

[Glensound]

Thanks for the info on the resistor change...

As for the operation of the meter itself, I find it kind of odd with the red areas... so does this mean that the ideal is to have the meter at 12 o'clock center for all bias and balance screwdriver settings? How does this work? Picture of the actual meter and screwdriver setting is enclosed.

 

[Westy56]

You want the corresponding hash mark settings for the balance and bias.
If you were setting the AC balance, you'd be good according to the pic.
The bias will need to be set on the bias mark to the right of the balance mark..