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Amplifier "pop"

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Terrance Wolf

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Carver PM900, great amp except it "pops" loudly when I turn it on or off. No inputs, no surge suppressor...loud "POP." The big EV speakers can take it, I think, but the audience cannot. How can I fix this? I'm not an engineer and any help is greatly appreciated.
 

dr pepper

Well-Known Member
Most Helpful Member
Welocme.
Carver make reasonable amps.
Had a quick look at the manual the amp has speaker protection, you shouldnt get a thump or pop at least at turn on.
A second or so after turn on do you hear a click from the prtection relays?, maybe that section isnt working properly.
 

Terrance Wolf

New Member
Thanks Dr. for your kind and thoughtful reply. No click a second after turning on, just the loud pop immediately. I've taken another tack here, I've ordered a speaker selector switch. So, I'll turn the speakers off before switching the amp. We'll see...
Thanks again.
 

dr pepper

Well-Known Member
Most Helpful Member
Its near impossible to diagnose by proxy, however it sounds like the protection circuit isnt working, the transistor that drives the relay might have shorted or something along those lines.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
This is one of Carver's magnetic field amplifiers. There is a free service manual at www.hifiengine.com. You have to register.

There are two service bulletins for this amp listed in the service manual.
One is for a speaker buzz. PM900 s/n below 711
One is for speaker noise PM900 s/n 1003 to 90X30900001 (Has a silver line filter - Delta Electronic 20DBAG5, not a TDK black one)

If your using the XLR inputs, make sure S3 is set properly for US or DIN standard for pin 3 being hot. The other inputs are not affected.
 
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