Qsc rmx 2450

[e_c_mccollum]

I've got a RMX2450 amp that buzzes loudly on channel 2.

I have replaced NE5532 pre-amp chips. Currently repairing soldering and cleaning boards (very dirty). I have schematic and any ideas will be welcomed.

[Enzo]

First, is there DC offset on the output? I mean is this the loud buzz of a blown stage? or does it pass signal but buzzes as well?

Work without a load for now.

Are the power rails for that channel up to proper levels and clean? Are they symmetrical? in other words do you find the +/-35v to be +55 and -15 or whatever? How much ripple on each rail?

[e_c_mccollum]

Amp does'nt pass any audio signal other than buzzing. Pwr supply voltages do match closely to schematic, but voltage on Ne5532 (channel 2) is +9 to 12v(changes), -12v. ??? Supposed to be +/- 15v.

[Chrome Dinette]

How old is that amp? QSC has a lengthy warranty(3 years I think).

[Mark Black]

Here ya go (hope this works - first time I've tried...)

Oops - just re-read your post & realized you already have it - Oh well...

RMX2450 Schem.pdf