Distorting Accuphase E-302 - 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 13th January 2007, 05:07 PM   #1
reins is offline reins  Germany
diyAudio Member
 
Join Date: Mar 2004
Location: Bayern
Default Distorting Accuphase E-302

Hi,

one channel of the power amp is distorting audible.

Does anyone have schematic available?

As I think it might be difficult to get the schematic and I'm no expert in solid state amps, might it be helpful to measure the test points and compare the the two channels?

Is there any chance for me to find the bug?

Thanks
Stephan
  Reply With Quote
Old 13th January 2007, 10:11 PM   #2
diyAudio Member
 
Piercarlo's Avatar
 
Join Date: Nov 2006
Default Re: Distorting Accuphase E-302

Quote:
Originally posted by reins
Hi,

one channel of the power amp is distorting audible.

Does anyone have schematic available?

As I think it might be difficult to get the schematic and I'm no expert in solid state amps, might it be helpful to measure the test points and compare the the two channels?

Is there any chance for me to find the bug?

Thanks
Stephan
If you don't have much experience in troubleshooting it's a bit hard to try. However, having a channel working, comparing voltage as appearing in the same points of circuit may be a good idea but you *must* have a good background of typical circuits used in audio and a good ability to guess that specific circuit is employed in the section you are troubleshooting. Is not an impossible task but neither a easy one.

Hi
Piercarlo
  Reply With Quote
Old 14th January 2007, 03:41 PM   #3
reins is offline reins  Germany
diyAudio Member
 
Join Date: Mar 2004
Location: Bayern
Default Re: Re: Distorting Accuphase E-302

Quote:
Originally posted by Piercarlo


If you don't have much experience in troubleshooting it's a bit hard to try. However, having a channel working, comparing voltage as appearing in the same points of circuit may be a good idea but you *must* have a good background of typical circuits used in audio and a good ability to guess that specific circuit is employed in the section you are troubleshooting. Is not an impossible task but neither a easy one.

Hi
Piercarlo

I fear that is true.

Even "worst", as the test points of both channels deliver nearly the same results.

But maybe its another problem (cables, relays, ..)?

Thanks,
Stephan
  Reply With Quote
Old 15th January 2007, 08:19 AM   #4
diyAudio Member
 
Piercarlo's Avatar
 
Join Date: Nov 2006
Default Re: Re: Re: Distorting Accuphase E-302

Quote:



I fear that is true.

Even "worst", as the test points of both channels deliver nearly the same results.
That "nearly" must be evaluated. "Nearly" may be harmless if in the range of 0.5 or 1 volt but these differences may hide subtle malfunctioning of circuits. Once again, in absence of a schematic, a previous background of circuits which may be employed in typical audio equipment (for guessing some of that are really used) is mandatory.

Quote:
But maybe its another problem (cables, relays, ..)?
Relay, especially if a bit weared-out by the years, are often the main causes of "crackling" amplifiers. You may beat their cases with the handle of a screwdriver and notice if something change. If the case, remove the covers and spray the relays with a suitable contact cleaner.

However, from other complaints i have eared, Accuphase (as many other industrial product builded with not-ever excellent PCB material) tend to suffer problems of cold solderings.
This may be a bit strange for someone because may be not easily understandable as a cold soldering which has well performed for years, suddenly cease to work. The key issues is "thermal stressing". Repeated cycles of warming-colding of equipment during the years, with alternate dilating and stretching of PCB materials (and components mounted on of course, included copper traces which are subject to be broken from this cycles, especially in section where an high thermal gradient is present, as typical in output stages with power devices directly soldered to the PCB) may easily conduct the equipment to these "strange" and "mysterious" fault.

Hi
Piercarlo
  Reply With Quote
Old 16th January 2007, 06:07 AM   #5
reins is offline reins  Germany
diyAudio Member
 
Join Date: Mar 2004
Location: Bayern
Default Re: Re: Re: Re: Distorting Accuphase E-302

Quote:
Originally posted by Piercarlo


However, from other complaints i have eared, Accuphase (as many other industrial product builded with not-ever excellent PCB material) tend to suffer problems of cold solderings.
This may be a bit strange for someone because may be not easily understandable as a cold soldering which has well performed for years, suddenly cease to work. The key issues is "thermal stressing". Repeated cycles of warming-colding of equipment during the years, with alternate dilating and stretching of PCB materials (and components mounted on of course, included copper traces which are subject to be broken from this cycles, especially in section where an high thermal gradient is present, as typical in output stages with power devices directly soldered to the PCB) may easily conduct the equipment to these "strange" and "mysterious" fault.

Hi
Piercarlo
That problem isn't new to me. My old Philips CD player suffers from that problem too. I'm still hunting hopefully the last sporadic malfunction there.

I thought: Not with Accuphase!

So I'll check for cold solder joins, maybe I have luck.

Thanks
Stephan
  Reply With Quote
Old 17th January 2007, 07:13 PM   #6
reins is offline reins  Germany
diyAudio Member
 
Join Date: Mar 2004
Location: Bayern
Super hint,

there where several suspicious looking solder joins on the amp board.
I have re-soldered them --->
And now the distortion is gone!

Thanks
Stephan
  Reply With Quote
Old 18th January 2007, 07:48 AM   #7
diyAudio Member
 
Piercarlo's Avatar
 
Join Date: Nov 2006
Quote:
Originally posted by reins
Super hint,

there where several suspicious looking solder joins on the amp board.
I have re-soldered them --->
And now the distortion is gone!

Thanks
Stephan
Of nothing! My old crystal sphere seem to be a good one again!

Hi Piercarlo
  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
Meridian MCD Distorting doarkface Digital Source 0 10th February 2009 07:47 PM
Distorting 5687 preamp circuit dsavitsk Tubes / Valves 13 14th June 2006 02:31 AM
Sub distorting - help please Simpleton Subwoofers 8 14th August 2005 06:56 AM
Mackie power amp distorting javey Solid State 2 20th April 2005 03:45 AM
Gainclone distorting in the higher frequencies jaume Chip Amps 9 26th March 2004 07:07 AM


New To Site? Need Help?

All times are GMT. The time now is 10:02 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