As the title states, I have a broken Behringer EP2500 amplifier that I'm trying to fix. It has some strange symptoms that I'm struggling to diagnose the cause of.
Channel 1 outputs an extremely distorted signal if the input signal rises below a very low level, as if the signal is being clipped. Neither the signal nor the clip LEDs illuminate. Adjusting the gain potentiometer changes the volume of the output but does not affect the level of distortion, as far as I can tell. The same thing occurs with Channel 2, except turning the gain potentiometer all the way down does not completely mute the channel.
After I tested the amp once, I tested channel 2 one more time but with the clip limit switch off and the gain all the way down. The speaker emitted a few high-pitched squealing noises and the clip light turned on until I unplugged the amp. When I tested channel one earlier, the clip limiter switch was off but this did not occur. The only cause for this that I can think of is some sort of oscillation caused by having both clip limiters off.
I've checked the fuses and output transistors but they all appear to be fine. A visual inspection of both sides of the circuit board doesn't reveal any parts that seem to be damaged.
Can anyone give me any pointers on where I should look next?
Thanks!
Channel 1 outputs an extremely distorted signal if the input signal rises below a very low level, as if the signal is being clipped. Neither the signal nor the clip LEDs illuminate. Adjusting the gain potentiometer changes the volume of the output but does not affect the level of distortion, as far as I can tell. The same thing occurs with Channel 2, except turning the gain potentiometer all the way down does not completely mute the channel.
After I tested the amp once, I tested channel 2 one more time but with the clip limit switch off and the gain all the way down. The speaker emitted a few high-pitched squealing noises and the clip light turned on until I unplugged the amp. When I tested channel one earlier, the clip limiter switch was off but this did not occur. The only cause for this that I can think of is some sort of oscillation caused by having both clip limiters off.
I've checked the fuses and output transistors but they all appear to be fine. A visual inspection of both sides of the circuit board doesn't reveal any parts that seem to be damaged.
Can anyone give me any pointers on where I should look next?
Thanks!