Just seen your post crossed over with mine.
Quote:
Originally Posted by OldTechFan96
FET Installation:
I am sure that I have the FETs installed correctly. None of the junctions are touching.
Y position is set dead centre.
IC in:
Pin 1- 1.9V
Pin 14- 2V
IC out:
Pin 7- 2V
Pin 8- 4.9V
Now the EY voltages are unbalanced:
EY1- 8.1V
EY2- 21.9V
R198 is getting very hot and IC001 feels like it is getting warmer than it should.
Thoughts as to what is causing trouble:
FET has been installed incorrectly. Will try other permutations.
BF256 is not a suitable replacement for TIS69.
EY output balance potentiometer has been fiddled with in the past. I'll wait for further comment before I attempt adjusting this.
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Ok, so input voltages are pretty close to one another (only 0.1v variance) although noted that they are some 1.5v higher than expected. However, the output at pin 8 of the IC considerably higher than at pin 7, which is amplified at EY1 and EY2. Before we draw te conclusion that the chip is fried, what are the VCC voltages at pins 5 & 10? Pin 5 should be at -5v, and pin 10 at +6.8v. If not, then one of the corresponding zenner diodes (Z001 or Z002) might be at fault.