Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Resurrecting a nOrh SE9 Integrated Amp
Resurrecting a nOrh SE9 Integrated Amp
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 4th July 2014, 05:03 AM   #1
wcakey is offline wcakey
diyAudio Member
Join Date: Sep 2010
Default Resurrecting a nOrh SE9 Integrated Amp

Need some help here.

I am attempting to resurrect a nOrh SE9 integrated amp. The problem I am having with it is that it will run seemingly just fine for about 10 min, then develops a hum and dies -- blows the 500 mA slo blo fuse. The tubes (5AR4, 2 x EL34 and 2 x 12AX7) work perfectly in other amps, so they are unlikely to be the problem. Switching out the 5AR4 for a 5U4 allows the amp to run about twice as long before it dies in the same fashion.

What is the most likely culprit causing the problem? Power supply caps, or some other caps or some resistor somewhere?

Thanks for any suggestions.
Attached Files
File Type: pdf Norh_SE9_Schematic.pdf (50.0 KB, 48 views)
  Reply With Quote
Old 4th July 2014, 09:53 AM   #2
DF96 is offline DF96  England
diyAudio Member
Join Date: May 2007
Check C6 and C7 for leakage. Monitor EL34 grid voltage.

The EL34 may be running a bit too hot. Check current by measuring cathode voltage. Calculate power dissipation. Should be below about 30W. Try putting a 470R in place of the 390R cathode resistor.
  Reply With Quote


Resurrecting a nOrh SE9 Integrated AmpHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
question about nOrh SE 9 amp for FE207E juanito Tubes / Valves 1 11th February 2007 11:10 PM
Resurrecting Old Speakers Brushpilot Multi-Way 5 4th July 2004 03:12 PM
norh pyramids atc747 Multi-Way 8 28th June 2004 05:19 PM
Most responsive tweaker SE9 or 102B tooboot Tubes / Valves 4 4th January 2004 01:14 AM
WTB: Norh SE9 or Jolida 102B Amplifier tooboot Swap Meet 0 3rd January 2004 06:06 PM

New To Site? Need Help?

All times are GMT. The time now is 02:13 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio