Please help on Mark Levinson No 331 amp repair - 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 7th May 2013, 10:31 PM   #1
diyAudio Member
 
Join Date: Jan 2010
Default Please help on Mark Levinson No 331 amp repair

Water damaged Mark Levinson 331 found me and I hope I can bring her back to life again. I washed all water marks and junks from water. Luckily, all transformers are OK but dirty water ate up leads of some parts on the power supply/ protection board. I do not have schematic to refer. Missing parts are near 5 volt voltage regulator. If someone can share schematic or just picture of power supply/ protection board around 5 volt voltage regulator, I will really appreciate.
Click the image to open in full size.
Thank You in advance.

Last edited by birdyman; 8th May 2013 at 12:05 AM. Reason: new pics
  Reply With Quote
Old 8th May 2013, 01:31 PM   #2
diyAudio Member
 
Join Date: Jan 2010
Here are the missing (lost parts) from water corrosion.
VSMB ( power supply board) R100, R102 and R49 and R51.
If any one now values of these or have hi- res pics around front right side and front center of board pics, may I ask you to share with me?

Thanks in Advance
  Reply With Quote
Old 9th May 2013, 12:18 PM   #3
diyAudio Member
 
Join Date: Jan 2010
I figured out all of values on missing resistors. But I still like to get a copy of schematic if anyone has it. I found extent of water damage is much greater than I thought because the amp was plugged in while under water. All BJT's on VSMB board are dead. Thanks for looking.
  Reply With Quote
Old 9th May 2013, 12:22 PM   #4
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
I spotted your post earlier. Water damage, and particularly where electrolysis has occurred is hard to put right. The corrosion eats into PCB print too. A starting point is washing a board (maybe with foam cleaner first) and then rinsing and drying.

I've worked on more "liquid damaged" items than you can shake a stick at over the years and its always bad news in severe cases. Problems can keep appearing.
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote
Old 9th May 2013, 02:05 PM   #5
diyAudio Member
 
Join Date: Jan 2010
If it was completely switched off it would been easy clean off and few repairs. This amp was in stand-by mode and all the bad things happened while electricity is flowing. Any parts with high supply voltage ( 20v DC or higher on this amp) was cooked and PCB was etched. Luckily ML331 did not have SMD's and high density PCB traces even though they would not release schematics. Wish me luck.
  Reply With Quote
Old 21st July 2013, 03:04 PM   #6
diyAudio Member
 
Join Date: Sep 2010
Dear Birdyman,

The value of the resistors you ask for, are: R49=1K/0.25W; R51=0.715K/0.25W; R100 and R102=10 ohm/5W
  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
Mark Levinson 27 Repair Complete Corvus corax Solid State 4 11th March 2011 04:06 AM
'70s Mark Levinson Op-amp thermionic Solid State 5 5th November 2008 07:18 PM
Need help on Lexus - Mark Levinson amp. mod. 100db Car Audio 5 15th February 2007 07:23 AM
30 amp power bar for mark levinson audio karma Everything Else 4 10th November 2005 10:22 AM
Mark Levinson Rosette & Korsun U2 confirmed the same Super_BQ Everything Else 15 12th April 2005 03:24 PM


New To Site? Need Help?

All times are GMT. The time now is 08:05 PM.


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