Dead/bad Caps in an NAD L40 - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

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 1st March 2007, 04:57 AM   #1
diyAudio Member
 
raromachine's Avatar
 
Join Date: Jun 2006
Default Dead/bad Caps in an NAD L40

Hi all,

I've offered to look at why an NAD L40 (CD + Radio + 2x 50w) integrated AMP has stopped powering up.

I've checked the transformer and fuses and I'm getting all the right voltages - however I've found that the highpower stage (+/- 80v with no load) is triggered by a relay, which in turn is triggered by some logic on the board 'somewhere'. I same somewhere as I'm not quite game enough to remove the hundred odd little plugs that go to various things on the board - so I can trace it's route on the reverse side.

I've also not managed to find an L40 sevice manual online - so I have no idea what all the test points mean.

I started to look at it in the day light and found a bunch of caps - all the same brand but of differing values (between 1000 and 2200 uf) which appear to be leaking/have leaked.

Click the image to open in full size.
Click the image to open in full size.

Is it likely that these caps are the cause of the problem? It appears they're in the power supply for the digital stage of the board rather than carrying any signals.

Any help/advice greatly appreciated!
  Reply With Quote
Old 1st March 2007, 05:40 AM   #2
AKN is offline AKN  Sweden
No snake oil
diyAudio Member
 
AKN's Avatar
 
Join Date: Aug 2005
Location: In the middle of Sweden
Send a message via MSN to AKN
Hi raromachine,

Shown in pics is probably glue, used to secure heavy components.
Broken caps will usually bulge in the top before starting to leak.
__________________
/ Anders
  Reply With Quote
Old 1st March 2007, 07:56 AM   #3
diyAudio Member
 
raromachine's Avatar
 
Join Date: Jun 2006
I guess the odd thing is that there are other bigger caps (68000uf) that aren't glued, and similar physically sized elna caps also not glued - hence why I thought it might be dried out electrolytic goop.

You're right - no bulging etc.

Back to the multimetering.
  Reply With Quote
Old 1st March 2007, 10:05 AM   #4
diyAudio Member
 
raromachine's Avatar
 
Join Date: Jun 2006
Hrm - it appears the caps are fine and it's the plastic cased JRC 7812 that's died - its twin the 7912 is working fine by the looks but it's the 7812 that supplied the +12v most of the amp. Very CURIOUS Indeed!
  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
bypass caps for bypassing mylar caps? crippledchicken Multi-Way 4 27th February 2008 04:24 AM
Replacing multi-section caps with multiple caps? Sir Trefor Tubes / Valves 1 29th May 2007 10:17 PM
uh, and i ******* up again, caps and rectifiers got ugly warm - dead? demogorgon Chip Amps 27 7th March 2005 10:45 PM
Replacing ceramic disc caps with silver mica caps? G Solid State 5 18th November 2002 01:02 PM
FILM Caps to assist Big ELYT Caps gromanswe Parts 0 9th July 2002 08:16 AM


New To Site? Need Help?

All times are GMT. The time now is 12:05 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