Faulty amp? - 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 7th September 2011, 08:35 AM   #1
diyAudio Member
Join Date: Aug 2007
Location: Sofia
Send a message via Skype™ to Mario Pankov
Default Faulty amp?

Hello all,

I`m not very much into amps, perhaps this is the best place to ask

I do own an old Denon PMA-860. Since an year or so I started to feel as it has lost its bass, one day I put a NAD 3020 into its place and it just confirmed the Denon is out of bass. Then, starting in this year it developed a crackling noise in both channels, I initially thought this might be because of the volume know ( I always run it source direct ) but contact spray didn`t help. Then, when I was doing some measurements on my speakers, I noticed that low volume sound comes from the other speaker, not the one I measure and its channel was disconnected from the amp. Today the amp produced a bump like the DC protection has engaged but it was not off. It kept working but no sound was coming out of the speakers. I connected a different speaker - no sound at all.
I guess the amp is dead but just wanted to confirm this?
  Reply With Quote
Old 7th September 2011, 10:22 AM   #2
diyAudio Member
Join Date: Aug 2007
Location: Sofia
Send a message via Skype™ to Mario Pankov
Just to add, I opened the amp today and noticed that when on standby ( no connected speaker or interconnects ) one of the two radiators was burning while the other one was cold. Each has four output transistors, I suspect there is a short in one of them?
  Reply With Quote
Old 7th September 2011, 12:38 PM   #3
jaycee is offline jaycee  United Kingdom
diyAudio Member
Join Date: Apr 2004
Location: Norwich, UK
I believe the input FETs are vulnerable on this amp - that is TR501-504 on the main board.

The hot channel points to a more serious problem - possibly a consequence of the damaged FETs
  Reply With Quote
Old 9th September 2011, 05:41 PM   #4
diyAudio Member
Join Date: Aug 2007
Location: Sofia
Send a message via Skype™ to Mario Pankov
Thanks for the input. I left it for servicing today.
  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
Help for novice - faulty amp Hodgie Solid State 4 25th January 2011 06:53 AM
MICROMEGA Drive 3 & DAC Faulty & MODS eldarvanyar Digital Source 7 28th April 2010 07:30 PM
Faulty NAD 4100 Tuner - help & suggestions needed stevecole Analogue Source 0 7th May 2009 09:39 PM
denom pma250 amp faulty,but no faulty parts found please help homertooties Solid State 1 7th December 2008 03:58 PM
Faulty amp - diagnosis? Omega_Void Solid State 7 11th July 2008 10:52 AM

New To Site? Need Help?

All times are GMT. The time now is 06:21 AM.

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