Jet City Custom 22 Depth Mod

[RFMann]

I do not have and can not find schematics for my Jet City CUSTOM 22 (not to be confused with the original JCA 22H)

I wish to install the depth mod. While studying my circuit board and trying to determine the NFB resistor, I originally thought it was R59. However, I think that assumption may be wrong. While staring at this thing, it suddenly dawned on me that the Custom 22 might have a fixed depth circuit in it. I realized that R59 which I was earlier questioning as the NFB resistor, has a capacitor (C10) in parallel, this has me thinking that R42 is the NFB resistor. Can anyone tell me if this is accurate or not?

Secondly, If this am does have a stock fixed depth mod in it, is it worth going through the trouble of installing a variable depth control?

Thanks!

[alexradium]

You probably have a 4n7 cap with a 100k in parallel,just replace that resistor with a 1M audio pot

[RFMann]

You probably have a 4n7 cap with a 100k in parallel,just replace that resistor with a 1M audio pot

You are correct. That is a 4n7 cap and the resistor does indeed appear to be 100k. I am glad you suggested replacing that resistor with the pot as I was hoping to head in that direction. It will certainly make that mod a lot cleaner. Thank you for your help.

[DFuller]

It's absolutely having a tweakable control. Takes two seconds to install, too.

[reeder321]

Did you ever perform the mod? planning on doing it myself however all of the diagrams I have found are for the previous version of the head which doesn't have the cap in parallel on the board and they run their pot in series with the existing resistor and put a cap in parallel on the pot itself. I'm hoping that on the custom 22 its as simple as just removing the R59 and replacing with the 1 meg pot.