Onkyo amp woes! - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

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
Reply
 
Thread Tools Search this Thread
Old 11th June 2013, 10:34 AM   #1
diyAudio Member
 
Join Date: Dec 2011
Default Onkyo amp woes!

Hi folks I am really struggling with an Onkyo amp for which I cannot find a scematic, it is an itegra A-819. Some of the driver trannys are dead in the left channel can I replace 2sc2238's a968's & 2sc1940's & A915's with all 2sd1138's & 2sb861's, I should imagine gain is surely not a problem! The other channel I am having trouble with the bias, I am measuring zero across the emitter resistors (0V on output with healthy main power supply, and healthy 22v secondary supply to opamp) and when injecting a sine wave this is appearing as a saw tooth on the output :-( I have not come across this particular diff amp and current source configuration before, not to mention the active bias and cannot find any obviously faulty components! Any help would be appreciated! Thanks.
  Reply With Quote
Old 11th June 2013, 04:41 PM   #2
diyAudio Member
 
east electronics's Avatar
 
Join Date: Jan 2006
Location: Athens GREECE
Measure if there is proper supply in the drivers ..often drivers are powered after fusible resistors in the area of 10 ohm or so if one of them is blown you get no drive no bias ...

also look at the obvious poor soldering , broken traces , and open resistors ...

In between i will take a look for a schematic also
__________________
SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr
  Reply With Quote
Old 12th June 2013, 02:15 PM   #3
diyAudio Member
 
Join Date: Dec 2011
Hi Sakis thanks for the reply, supply to the drivers is fine as far as I can see, and there are no fusible / out of range resistors :-( The OPamp, part of the servo bias seems to be outputing 2.5V with zero on the output which I would not expect though!?
  Reply With Quote
Old 16th June 2013, 08:09 PM   #4
diyAudio Member
 
Join Date: Dec 2011
hi folks I have stuck this to one side at the moment, but if anyone could give me any pointers, or help with a diagram I would be quite grateful :-)
  Reply With Quote

Reply


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
Amp woes... Denon POA2400. mortron Solid State 12 15th April 2013 04:29 AM
Amp woes... Denon POA2400. mortron Solid State 0 11th April 2013 04:52 PM
Nad S100 pre-amp woes timpy Analog Line Level 3 19th November 2009 11:27 PM
Usher pre-amp woes... Illusus Solid State 15 25th September 2004 02:04 AM
Pre-amp woes mluckey Solid State 1 31st October 2003 07:20 PM


New To Site? Need Help?

All times are GMT. The time now is 02:43 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2