Mind print DTC Tube compressor calibration fault

[blindboybenton]

This one is beginning to do my head in.

It came in to me a while ago for a switch problem, Fixed that the owner said that one of tone filters wasn't working
I sorted that it was a pot. He always said it works ok but does not think its working 100%
Compressor_adjustment_E.pdf
Mindprint _DTC.pdf

Anyway on final test i noticed that Channel B when you turned the compressor on it wasn't compressing at the same as ChA
This is done with same signal injected into both with all the tone/filters off and Compressor levels all the same.
When you check output without compressor on. Both outputs are prefect

If i turn the Trim pot TR1 on both channels full clockwise i would expect that the signal output would be roughly the same but CHB is higher. Both sets of LEDS are spot on. I knew there is some adjusters for the LED display. They are working

Channel A is the top
without any compression
Replaced both tubes for brand new ones

This unit has had a lot of repairs in the past and is a nightmare to work on. One main board and 3 sub boards . Lots of ribbon cables hard wired and one end and connectors at the other. Ive gone thought the hard wired connectors and remade most of them. Very hard work trying to work on and scope out and compare, I don't have brilliant test kit. I have checked that its not my scope etc

Not sure if im doing anything wrong, but im sure there is something wrong. Out of my comfort zone

please if anyone can assist

Bassman

[blindboybenton]

Looks like nobody's going to help me ?

[gbono]

Have you tried chasing the signal through the channel B and comparing each node to channel A circuit? You might want to bring this topic over here since it really is a "solid state" (i.e OP amps) design with some tubes in the output: Amplifier Discussion

[blindboybenton]

Ive sort of tried, But the layout makes in very difficult due to the 3 sub boards . was hoping for a few idea's on looking at the map on where to look. I will make another tread in the forum above.

Thanks
Bassman

[Jazz P Bass]

The 'limiter' appears to be IC 7.

There are a few switches that have to be made for it to receive the correct signal.
Prove out the switrches first.

Then, I would recommend looking at IC 7's output & comparing it to the working channel.

[blindboybenton]

You are a star Jazz P Ive been avoiding this for weeks today i decided to take a look and i had forgotten what channel was missing behaving and looked at chA
and i saw a very small solder splash across a switch and now i can calibrate it and it working correctly.
Hopefully none of the ribbon cables have bust
Bassman