Tube Tech CL-1B Calibration Issues

[smilan]

I'm trying to calibrate a CL1-B and I think something is wrong with this unit.
First thing, when turning the unit on, with the meter showing compression the movement jumps to the max (over 3) and it takes more than 15 minutes for the movement to set on the 0 mark.
Second, when the threshold causes a gain reduction and then sets back to the OFF position it takes more than 10 seconds for the movement to reach back to the 0 mark.
I followed the calibration instructions and as far as compression everything seems to be calibrated correctly, the voltages at the input and output are sync with the VU meter, but as soon as I'm switching the meter to show input / output there's a mismatch between the VU reading to the voltages at the input and output.
It seems to me like something with the meter circuit is wrong, but I can't find a schematic for the sidechain board.
Maybe someone here have the schematic for the sidechain board? / have an idea how to make the meter calibrated well?
BTW, yesterday I sent an email to tube tech, but until now did not get a reply, maybe today I'll get some support from them.

 

[beatnik]

The La-2a metering also takes a few seconds to get back to 0 after gain reduction has been applied, maybe that is common with optical compressors

This is the service manual I have

 

[smilan]

The La-2a metering also takes a few seconds to get back to 0 after gain reduction has been applied, maybe that is common with optical compressors

This is the service manual I have

Thank you for the schematics!

Since P4 control over the time that takes to the movement to return to 0, and when there's maximum resistance between the +15V rail to the cathode of D4 the return is faster compering to less resistance between those points , there's a reason why not to increase the value of R10 a little and to bring the movement faster to 0?

 

[kags]

After several dB of compression, the LA2a can take almost 3 seconds to return to zero—simply based on the actual release time of upwards of 2 seconds. The CL1b can also have a release time of as long as 10 seconds. Could be the release is set improperly or the circuit is misbehaving. When set to the fastest release, after a few dB of gain reduction, the meter should return almost instantly to zero.