Go Back   Home > Forums > Amplifiers > Tubes / Valves

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

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 18th August 2012, 03:30 AM   #1
diyAudio Member
 
Join Date: Aug 2012
Default Music angel el34b problem

Hi guys,

I've got one of these chinese thingys:

http://hi-end.on9mart.com/products/a...3-photo_04.JPG

Bought off a well known auction site...

It was working brilliantly... until i decided to fit magic eye vu meters to the sucker. I proceeded to burn out 2x resistors on the tube socket side of the board. Does anyone here have a picture of that side? I can find plenty of the underside of the board, just not the top.

How it blew: I hooked up the magic eye board as it should be (or how i thought it should be) and turned it on. no input connected & volume at minimum. after about... 6 seconds one resistor caught fire (yes. fire.) and the second followed shortly after. as a result i am unable to identify the values to replace them.
It turns out the magic eye tube socket was on the wrong side of the board - me= stupid for doing that. and a short circuit resulted. I have since removed the magic eye stuff so i can focus on getting the amp back to normal.

(i suppose this is what i get for assembling a kit without instructions) It would have been nice if the guy i got the kits off supplied me with them, but the damage is done. Now it's fixing time!

I'll see if i can rustle up a pic of the board soon
Thanks in advance...
  Reply With Quote
Old 18th August 2012, 04:07 AM   #2
diyAudio Member
 
Join Date: Aug 2012
Here's the board...
Not in it's original case. I butchered a bamboo cutting board & glued some hardwood to it.

The pics might not be too clear, but l/h channel went from pin 4 of the two el34s to a 220UF cap (big sucker)
the r/h did similar, but the cap is a 180.

Without the resistors it sounds like a boss DS1 distortion pedal maxed out. and really quiet. not exactly the sound i was after...

When i guestimated the values (1k for L/H & 4.7k for r/h - from what colours i could make out), it made an almighty squeal/bassy rumble that terrified the neighbours dogs

The other possibility is when i blew the resistors i may have damaged the tubes, but i'll start with replacing these 20c parts first.
Attached Images
File Type: jpg amp1.JPG (222.0 KB, 107 views)
File Type: jpg amp2.JPG (170.8 KB, 102 views)
  Reply With Quote
Old 18th August 2012, 10:07 AM   #3
Cookj is offline Cookj  Belgium
diyAudio Member
 
Join Date: Aug 2004
Location: Bruxelles
Pin4 on EL34 is Screen Grid, there should be 4 resistors all same value. Try 100ohm 2 Watt

Regards

John
  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
New problem with Music Angel KT88 alecu7 Tubes / Valves 31 17th August 2012 08:15 PM
Music Angel knutech Tubes / Valves 1 3rd June 2011 08:15 PM
Music Angel KT88 Bridged /Bias problem kongarne Tubes / Valves 1 30th January 2009 01:57 PM
Music angel amps arvin Tubes / Valves 19 3rd March 2008 10:02 PM
Music Angel franckM Tubes / Valves 11 10th June 2007 11:24 PM


New To Site? Need Help?

All times are GMT. The time now is 02:26 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