NAB 3100 problems - 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 19th August 2012, 10:58 PM   #1
crite40 is offline crite40  New Zealand
diyAudio Member
Join Date: Aug 2012
Location: helensville New Zealand
Default NAB 3100 problems

Good day all! Just joined this forum.
FYI my own stereo system is a home made copy of the Quad 405 series (50 watts
channel) with an upgraded Doug Self preamp. Wharfedale speakers and usual programme sources.
I still do a bit of servicing for various people though I mostly restore vintage radios etc for museums and private collectors these days.
My post is about an NAD 3100 which recently came in for repair from an old friend. Once I got the cover off, I was a bit dubious about the design. I do NOT
like all those power devices crammed together in a row.
Then I found the first fault. During manufacture a small solder bead had been left in the unit and it had managed to short out a driver transistor with serious results.
I downloaded a service manual and just happened to note that NAB recommended that after working on the output stages the unit should be first run with a variac transformer or a series bulb load!
Big warning sign! Over my many years of experience I have come across other amps which have dc stability problems, and they were often fatal!

However I took another look and realised that several small resistors in the power stages were "cooked". Then despite being very careful a meter probe slipped and more cooking took place.

Result. I won't be recommending this firms amps to anyone who asks.
Although very pretty, the board layout of the power stages and the stability is not up to par.

I have been involved in electronics for over 60 years.
  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
Passive NAB Tape Preamp? tmblack Analogue Source 11 19th June 2012 08:18 PM
NAB Carts Doz Swap Meet 0 26th January 2011 02:27 PM
NAD 3100 Schematics 2002tii Solid State 12 15th July 2008 11:51 PM
Threading NAB spools stevers Analogue Source 5 22nd January 2006 01:54 PM
REAL diy, dang nab it! DSP_Geek Everything Else 0 23rd July 2005 11:25 PM

New To Site? Need Help?

All times are GMT. The time now is 12:44 PM.

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