Channel out - Repair Question - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

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 28th January 2013, 12:04 AM   #1
Muddler is offline Muddler  United States
diyAudio Member
Join Date: Oct 2009
Location: USA
Default Channel out - Repair Question

I have a 12 channel amp with one of its channels out and I would like to try to get it working. The other channels all work fine.
Each channel has an individual fuse, but the fuse is fine.
Nothing physically looks amiss.
There are six output? boards, three on each side mounted to the sinks.
Each board handles 2 channels and seems to have a mirrored set of components (top half / bottom half)
with 2 - 15K caps on each board.

The only clue I have thus far is that all of the channels' DC offset looks fine (most below 10mV), but when I switch to read AC (still using no input) the AC values seem to be similar to the DC ones except for the channel that is out.
It is measuring about 300 mV AC.

Does this narrow it down at all and give any insight to what I might be looking for?
Ie. - One of the big Caps, the output transistors, etc...
The caps physically look fine, only about 7 years old with no leaking or bulging.

As an aside, I remember speaking to a tech years ago that mentioned that these whole house amps often had their last channels go bad because installers would run out of channels and start chaining too many speakers off the end channels. Although I have no idea if this was the case.

I don't think it is going to be possible to get a service manual or schematic.
Thanks in advance for any help.
  Reply With Quote
Old 28th January 2013, 01:00 AM   #2
DUG is offline DUG  Canada
diyAudio Member
Join Date: Jan 2003
Location: mississauga ontario canada
With power OFF, start measuring components and compare the "bad" channel with a good channel. (or good channels)

See what you discover and go from there.

If it is within your ability you might try to draw out the schematic.

If not, then note part numbers or other identifying labels of anything you can.

Sometimes one part will fail and take out one or more other parts. You may have to check the parts again after any single part is replaced.

I would recommend not to power it up after repair until you are satisfied that the bad amplifier is measuring close to the good ones.

Good luck.

Doug We are all learning...we can all help
"You can't stop the signal, Mal. Everything goes somewhere..."
  Reply With Quote
Old 28th January 2013, 02:24 PM   #3
Muddler is offline Muddler  United States
diyAudio Member
Join Date: Oct 2009
Location: USA
Thanks Dug, I will certainly do as you suggested and try to use the working channels to shed some light.
However, I am still curious as to whether there being AC at idle with no input is indicative of a certain type of failure. The other channels do not have this.
Besides the six boards (I will call them output boards because I don't know what they would really be called) there are two other boards that all the channels go through also.
One sits vertically across the back that has all the input and outputs. The other sits horizontally across the bottom that contains all the fuses and is where the transformers wires go and is where the output to the terminals comes from.
I was hoping to take an educated guess at which board to start looking at. My hunch is the smaller board that has the transistors and caps, I am wondering if this seems to be the most likely place to start.
  Reply With Quote
Old 28th January 2013, 03:48 PM   #4
diyAudio Member
Join Date: Jan 2011
Location: Fosser, Aurskog-Holand, Akershus, Norway.
Nice hi-def closeup pics would actually help a lot.
Sooner or later you end up with TANDBERG

Last edited by TANDBERGEREN; 28th January 2013 at 03:51 PM.
  Reply With Quote


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Trying to repair Samson SX1200 w/ blown outputs on one channel jamesmafyew Solid State 25 24th April 2016 09:56 AM
Memphis Audio 4-channel amp repair 16-MC3004 ALLMemphisCarAudio Car Audio 1 19th July 2012 09:07 AM
Luxman rx-101 blown channel repair Merzie Solid State 9 22nd May 2011 01:05 PM
Anyone in the Dallas area to repair a single channel of a Golden Theater GTA-1? BHTX Swap Meet 0 21st July 2009 10:29 PM
DUAL 510 - Only one Channel - Repair Help! sbolduc Analogue Source 0 23rd April 2009 08:30 PM

New To Site? Need Help?

All times are GMT. The time now is 12:32 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2