Qsc rmx 2450

e_c_mccollum · 12-13-2008, 05:33 PM

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 · 12-13-2008, 11:24 PM

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 · 01-13-2009, 01:08 AM

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 · 02-07-2009, 04:36 PM

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

Mark Black · 02-08-2009, 12:06 AM

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

12-13-2008, 05:33 PM	#1
e_c_mccollum Member Join Date: Apr 2007 Location: Brownsville, Texas Posts: 88	Qsc rmx 2450 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.

12-13-2008, 11:24 PM	#2
Enzo Senior Member Join Date: May 2006 Location: Lansing, Michigan, USA Posts: 10,366	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? __________________ Education is what you're left with after you have forgotten what you have learned.

02-07-2009, 04:36 PM	#4
Chrome Dinette Junior Member Join Date: Sep 2008 Posts: 15	How old is that amp? QSC has a lengthy warranty(3 years I think). __________________ www.youtube.com/sicherheit www.myspace.com/microwaves

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01-13-2009, 01:08 AM	#3
e_c_mccollum Member Join Date: Apr 2007 Location: Brownsville, Texas Posts: 88	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.

02-08-2009, 12:06 AM	#5
Mark Black Senior Member Join Date: May 2006 Location: Near Seattle, WA, USA Posts: 341	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

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