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Topics - Superpunky

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Amplifier Discussion / Coxx GG-30 with low volume issue
« on: December 02, 2020, 08:29:57 AM »
Hi everybody,
I have a Coxx GG-30, a 30W combo solid state with a low volume issue which is driving me crazy :duh. The guitar can be heard only with all volumes (including equalization controls) at max level.
I tried to search for the schematics online, but they are impossible to find and there's not an official site. Maybe it's a rebrand?
The circuit board is based on an LM1875T and uses two 072D IC for pre and effects i guess (attached images).

Here is what I did/found:
- The low volume issue affects also the heaphones output
- The volume is low both on clean channel and with overdrive. I tried to use both inputs (high and low Z).
- I made a reflow of almost every soldering
- Potentiometers are OK
- The power supply is OK, +- 25V are everywhere needed
- I tested the resistors and they seem to be ok
- I tested all the capacitors onboard and none of them seems to be shorted
- Update: i tested both 072D. All 4 OpAmps are working correctly

Considering that I don't have an oscilloscope here at home, are there any tests that you can suggest to do to find out what's happening? Also, is there a way to find the schematics online?

Thanks!




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