Behringer EP 4000 EUROPOWER - clipping too early

[xavlaur]

Hello ! I have 2 Behringer amplifiers with below problems:
Behringer EP 4000 EUROPOWER - no.1 - premature clipping
It enters clipping too early (red LED clipping on), at around 15W, it starts to distort, if I reduce the potentiometer the red LED still stays on for a few seconds and still distorts - after a few seconds the red LED goes out and no more distortion , but only at low signal.
There is no DC on output and no idle current.
DIP_SWITCH does not change the premature clipping behavior.


Behringer EP 4000 EUROPOWER - no.2 - distortions
The left channel distorts strongly
Transistors checked as diodes = ok. Currently, some of the diodes checked = ok. I'll check the rest.
There is idle current - 0.5 A and DC on 3.5V output, without the possibility of adjustment from the 3 semi-adjustable.
If I turn on the load, the DC output drops to 0.05V and I have an audio signal on the X21 / pin 7.
No load, no audio signal on X21 / pin 7.
As you rotate the VR4 upward, the distortion disappears for a second as if the transient mode were to ensure proper polarization.

[lazyman]

Check Mosfets for rail switching, 50n06