Bias Sensing circuit on SVT Classic.

[phsyconoodler]

Does anyone have any info on the bias sensing circuit in the SVT Classic amps?I have one that has an issue.The amp works fine and the current is correct,but the sensing LED's won't work properly on one side.The green one won't light up.The circuit is very complex and I've changed out the TLO72 and TLO74 IC's but it still isn't sensing properly.
  I'm not that great with solid state stuff which doesn't help much.
If anyone has experience with this issue I'd sure like some insight.
Thanks!

[PRR]

Link to schematic?

[scarlett amps]

be sure to check the 1 watt 10 ohm resistors. They occasionally die and then the leds dont work. if you need the complete schematics for this amp i have them, just send an email addy.
These amps are a complete pita to work on! i have fixed a dozen or more of them and they are never simple.
paul

[phsyconoodler]

Thanks for the insight Mr.Scarlett
 
PRR,
  I can E-Mail you the schematic if you like.

[phsyconoodler]

I found the problem!!
  On the output tube PC board there are some 220 ohm 1 watt resistors. R7 was open even thought it looks fine.Nasty to work on but easier once you just grin and bear it!
 

[scarlett amps]

yup those also blow often enough if a tube dies. What a pain to service!