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Topics - Superpunky

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Amplifier Discussion / Fender Frontman 212R with distorted sound
« on: March 01, 2021, 10:39:48 AM »
Hi forum,

I have a Fender Frontman 212R (not FM212R) with an issue of distrorted/crackling sound when the guitar is played. The distortion/crackling happens only when the guitar is played, when the source is muted there is no sound on the speakers. Both speakers are working correctly.
The issue persists connecting the guitar on the Power Amp also, so there's something wrong in the power amplifier section (lower right section in this schematic). https://idoc.pub/documents/fender-frontman-212r-schematic-ylyxvo69mznm

I tested all the capacitors on board and they seem to be ok. Solderings seem to be ok as well.

Did this happen to any of you? What tests should I do to find out the issue?


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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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