EV sb a760 subwoofer, sm or schematic

[Vicus]

Hi, I have to repair the power amp of the subwoofer model sb a760. Someone have the schematic or the service manual? The schemtic of some similar amp would be usefull. It's a class H power amp, with 2SC5200 and 2SA1943 output transistor.

The faulty is in the base voltage: I have almost the negative rail.

[Vicus]

It seems like the Dynacord SUB 800A so I look into other Dynacord class H amplifier and I found that CL1600 is similar. I found a leaky medium power pnp transistor. After replace it the amp did work but after about 30 seconds the output transistor blows up. I hope that's due to the thermal runout, I don't attached the power device to the heatsink. From time to time also best ones do stupid things.

[g1]

Oops. Good luck. Hopefully not too much fresh damage.

[Vicus]

With new output transistor and the right setting of the idle current the amp works fine.