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View Full Version : PB12 information as requested



4313B
12-10-2004, 04:50 PM
http://manuals.harman.com/JBL/HOM/Service%20Manual/PB12%20sm.pdf

Donald
12-10-2004, 06:49 PM
Hmmm, now maybe I can fix my dead one.

4313B
12-10-2004, 07:02 PM
You too huh?

LE15-Thumper
12-11-2004, 01:02 AM
I have had the same unit my shop twice now in as many months. The FET outputs keep blowing and I don't believe it has to do with overdriving, But thanks to Giskard, (A real gentleman and a scholar by the way) I will get to the bottom of this. The included mods and bulletins had some mention if the fets. I will keep the group up to date.

Thumper

LE15-Thumper
09-28-2005, 04:20 AM
Well, this thing is a real freakin' nightmare. This cct is so unstable. There are two versions, one with an output module and one with FETs mounted on a heatsink.My experience is with the later. I spoke to Harman parts and they have no service support available on EITHER design. I was hoping to get an entirely new assy, but nooo. No stock on entire boards or the S64AMI output module.
All I can say is that these amps have some sort of inherent design flaw. They are everywhere in a state of disrepair. I wouldn't doubt if 50% or more are out of commision, PERMANENTLY ! I had mine idling just perfectly on my test bench, they draw about 10 watts idling ! Ran it on my test Sencore test jig at about 25 watts output and the thing was as cool as a cucumber. Re-installed it in the box, powered it up and nothing ! Took it out, all my FETS were shorted as well as the driver transistors. The woofer is fine BTW. Like I said, A real POS and PITA

Alex Lancaster
09-28-2005, 04:44 AM
:) I had a good experience with Harman service, they gave me a good deal on a new S120 PII, I had to mail them a cut up cone, but I reconed it here very cheaply and bought a 350W plate amp from Parts Express, o yeah the sub had a stinking and unobtainable AMI module, it was out of warranty, if it had been, they would send a new complete sub; so, try emailing JBL or Harman service, they might give You a deal, if not, get a plate amp for about $150; The problemwith using Your extra amp, is that You would need a xover, too much :bs: .

Hope it helps.