Fender power chorus clean channel low output

[Steveierob]

hi, 1990s fender power chorus (i believe it’s very similar to ultimate chorus) problem on clean channel:
it sounds perfect but just lacking in volume, drive channel is as loud as it was when new.

i saw a post from 2016 where nickb helped someone diagnose problem with channel selection due to failing jfet, anyone got any ideas of likely cause for this reduction in available volume on the clean channel?

this is an ultimate chorus schematic, I can’t find one for the power chorus anywhere and fender refused to send me one when I emailed them

https://www.manualslib.com/manual/10...?page=9#manual

Any info gratefully received

steve

[The Dude]

Here's the schematic. Fender was kind enough to provide test points throughout indicating signal levels. I would insert a test tone and follow the schematic through to see where signal is low. If you have a scope, use it. If not use a DVM set to AC volts.

[Steveierob]

Thanks very much for the schematic, I will take your advice - just hope my old scope and signal generator still work!
btw, are you a registered tech? Fender told me that they would not give me the schematic

[The Dude]

I found it via a Google search. I no longer do Fender warranty work, although I did at one time.

[Steveierob]

Thanks again. When I completely wreck the amp, I’ll come back with more questions :-)

[Steveierob]

Hi again to the kind chap who sent the scan, Im trying to fix that amp and unfortunately the scan quality of the schematic is not great, I can barely read it - I am struggling to see test voltage figures.
do you have a pdf? Or is your original scan of better quality than the upload