Copicat Mark IV Echo - Low Feedback Level

[smilan]

Hi, I have a Copicat Mark IV Echo with a very low feedback (sustain) level.
I was managed to increase the amount of feedback by reducing the value of the 22k resistor (marked in green in the schematic) to 10K.
But compared to another copicat echo that I have (with a 22k in this position), the feedback level is pretty weak.
What else can making this issue?

 

[mrclunk]

Have you changed that coupling cap just below it?
If you haven't already, i'd change all the electrolytic caps. In my limited Copicat experience most electros are dry / leaky by now.

 

[smilan]

Have you changed that coupling cap just below it?
If you haven't already, i'd change all the electrolytic caps. In my limited Copicat experience most electros are dry / leaky by now.

I installed a new cap with no change in the feedback level. The original cap value was 6.8uF and the closest value I have here is 10uF, there's a chance that a smaller will increase the amount of feedback?

 

[mrclunk]

No, will just change the freq response a touch.
There's the cap on the sustain transistor base u could swap out?


What about the "swell' control, is that 'on'? Check the footswitch socket, think it'll be 'on' by default.

Actually isn't it the swell control that's doing the feedback??

Sorry, just thinking outloud here.
Some actual professionals will chime in soon...

 

[smilan]

Actually isn't it the swell control that's doing the feedback??

The swell control setting the amount of echo that will be added to the dry signal.
The sustain control sending the signal from the playback heads to the recording head to create a feedback loop.

 

[MagnetoSound]

So that cap off the SUSTAIN pot wiper is the next suspect.

 

[NoisyIndividual]

I assume you have adjusted the positions of the record and playback heads for optimum levels?