Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Class D Switching Power Amplifiers and Power D/A conversion

Klipsch Subwoofer issues
Klipsch Subwoofer issues
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 14th August 2012, 04:34 AM   #1
lazzer408 is offline lazzer408  United States
diyAudio Member
lazzer408's Avatar
Join Date: Sep 2010
Location: Chicago
Default Klipsch Subwoofer issues

I bought this sub at a garage sale for $20 "as-is" (broken) and the story goes like this...

The original owner said it stopped working and he gave it to his friend to fix. His friend said he had it working again but it still had issues. He gave it back and it went out for the garage sale. It's powered by a 200w BASH amplifier.

What it's doing is this... It will sometimes power up and play but when something loud "thumps" it goes into oscillation and sounds like 2-bit digital audio. A squeel that fluctuates with the music signal. The volume control still functions when the problem is happening. It's mostly SMT on a dual-layer PCB and following traces is a pain because they keep switching layers.

What I noticed are two regulators that have been replaced, a 7812 and a 7912 but what's interesting is the supply to pin-1 of each regulator is +28v. I'm placing my dvm's negitive on pin-2 for testing. I would think the 7912 should be on a negitive rail but it's not. The output of the 7815 is +14.95v. The output of the 7912 is +13v and unstable. Interestingly, if you subtract the regulators rated output voltage (15v) from the supply voltage (28v) you get 13v which is what it's putting out on pin-3. Almost like it's working backwards. Maybe because it's on the wrong rail.

I wonder if the "tech" accidently put in a 7915 where a 7815 should have been. Considering the voltages I'm measuring, I'm tempted to drop in a 7815 and try it.

Any reason I shouldn't?

EDIT - nevermind I think thats ok. I forgot the negitive regulators swap pins 1&2 vs. the positive regulators. Positive regulators are 1in 2gnd 3out. Negitive ones are 1ground 2in 3out. In which case the 7915 is outputting 14.93v.

Guess I have to look for other issues.

Last edited by lazzer408; 14th August 2012 at 05:14 AM.
  Reply With Quote


Klipsch Subwoofer issuesHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Klipsch KSW10 Subwoofer metalwheel Subwoofers 0 29th September 2010 04:58 AM
200watt Klipsch Plate amp Subwoofer NICE Zero Cool Swap Meet 8 11th June 2010 03:25 AM
Subwoofer amp issues and questions LLDeese Subwoofers 23 12th April 2009 09:46 AM
Gas tank and subwoofer issues? michael Car Audio 2 8th May 2006 09:48 AM
vented subwoofer vs room issues? Ilianh Subwoofers 8 14th December 2002 08:13 PM

New To Site? Need Help?

All times are GMT. The time now is 01:28 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio