audio:mcintosh:mc240

MC30 thru MC275 all, if you have increasing distortion as the volume is increased check the second stage, V2, 12AU7 Phase Inverter, pins 1 and 6 must be at the same voltage (265V), if not replace the .22 uF capacitor on pin 7. The grid bias is derived from a 2.2 M ohm resistor, if this capacitor as any leakage it will upset the bias voltage resulting in the phase inverter outputs being unbalanced.
replace silicon rectifier with 1N4007 and 470 ohm resistor (check this, it's in the restoration video)
- change 1.8K series resistor to 5.1K, check bias for -45 or slightly higher (-46) when B+ is at 435V on the KT88. If you have a fully meterd variac it should draw 1.2A at 120V.
- While you are at it replace the bias filter, a 22uF 450V cap will stiffen it up and last forever. (? I think 12uF is stock?)
- The value should be about 470 Ohms, you may have to adjust it slightly to get -52V on pin 5 of the 6L6 with the voltage on pin 3 at 470V. I use a variac to make sure the plate voltage on pin 3 is at 470 before I measure pin 5.
If a pair of resistors is marked 1% in the schematic this means to each other not the listed value.
For all resistors in McIntosh, unless noted otherwise they are 10% tolerence.