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I have a JBL PB12 the green lights are on but no sound?

Posted by donovan_3 on


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Bud Martin

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TV 954

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SOURCE: jbl PB12 powered sub woofer problem

These subs have had many problems, all associated with the amplifier section. PB 12's with an "M" as part of the ser. no. were assembled in Mexico and these are the ones with the amp problems. JBL fixed mine and sent it back no charge, BUT it cost me nearly $100 to send it to them in the first place. I have another one that has had no problems at all. Try sending it back for repair. At best you'll get a rebuilt unit back, at worst a substantial discount from the company for a new sub.

Posted on Aug 09, 2007



SOURCE: jbl subwoofer PB12

replace c42 100uf 16v capacitor

Posted on Apr 12, 2008


Joe Lamb

  • 463 Answers

SOURCE: pb12 makes thumping sound after warming up

Hello there..Thats normal only if your sub volume and the pre amp is turned up..Your amp is the cause of the speaker jump..Turn amp volume sub level down a few and check your wire from sub to amp..If all of that is good is a normal operation for pre amp warm up in sub if level is turn to max..Try unplugging amp freom sub then turn sub on stand alone(just sub outlet plugged in and no wires from base amp plugged in..If sub stops the its the amp making the problem..If it still is there then the pre amp is either dusty on inside or the outlet plug that it is plugged in doesnt have a good ground..Hope these help to solve your problem..Have a great day...

I’m happy to assist further over the phone at https://www.6ya.com/expert/joe_a3369546f8067589

Posted on Apr 03, 2009


  • 133 Answers

SOURCE: JBL Powerbass PB12 When left on, will make very loud sound

Before you spend a lot of money, try checking for these:

- poorly soldered or partially desoldered wires, connectors (power, signal input) or ANY other components (especially the ones that tend to heat up, like power transistors or voltage regulators - a component which has been heating up will cause the curcuit board around it to become somewhat darker)

- dirty or oxydized contacts on ANY of the connectors or switches

- partially or fully blown electrolytic capacitors (see if any are damaged, bulged or blown at the top, these surely need to be replaced)

- internally damaged tantalum electrolytic capacitors (probably there will be no apparent damage to these, but they may cause intermittent disturbances if they are bad).

It may as well be something else, but if your equipment was being used extensively during these 6-8 years, it is likely that some capacitors may have dried up or otherwise failed.

It is also likely that the sound vibrations caused loose connections or bad solder contacts on the circuit board since it is a powered sub with an integrated amp (many audio devices get to suffer from bad solder contacts just by heating up with years of use and even without being exposed to powerful sound vibrations).

I hope you can get it to work well again.


3rq8 (Triarcuate)

Posted on Sep 07, 2009

Testimonial: "Thanks! I wish I had your knowledge. I will take a close look,check everything you mentioned the best I can, and see if I want to repair or replace"


Bud Martin

  • 11361 Answers

SOURCE: JBL PB12 is 10 years old and I have red lights but no audio.

Service manuals: http://manuals.harman.com/JBL/HOM/Service%20Manual/PB10%20sm.pdf

My ClassD module shorted out (buzzing sound/blown fuse) and not availabled any more so this is what I did: http://s807.photobucket.com/albums/yy352/budm/JBL%20PB-12%20mod/
I would suggest to buy new one.

Posted on Apr 01, 2010

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JBL PB12 will have loud thump or pop!

First try to find the source of your problem. The easiest way would be to try your sub with a different audio source to see if the problem still occurs but is sounds more like there's a problem with the receiver.

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Perhaps it could be the capacitor as mentioned above - but it could be any number of other issues - if that don't fix it - send it to us - Edwards Electronics - Ebay - Check Auction - Thanks

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Here are the service manuals, you may what to read the service bulletin section. Most common failure in the PB10/12 is the blown ClassD amp module which you cannot get it anymore. This is how I fixed my: http://s807.photobucket.com/albums/yy352/budm/JBL%20PB-12%20mod/

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these a internal power control board defective, send to repair

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if your serial number starts with ha then it's probably a bad capacitor C72 . 6.8uf 100v np electrolytic. replace it with a higher voltage capacitor of the same value.

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