Help - valve won't fire - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Instruments and Amps Everything that makes music, Especially including instrument amps.

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 24th August 2015, 02:02 AM   #1
diyAudio Member
 
Join Date: Aug 2015
Default Help - valve won't fire

Hi all,

I just finished building a 15W tube guitar amp at an amp building course. It worked fine when I finished the course, but when I got home it wouldn't work. The 2 power tubes glow, but only one preamp tube glows. I swapped the two preamp tubes around to check if it's a bad tube but it worked in the other spot. I'm getting no guitar sound from the speaker except a very gentle hum that responds to the master volume control.

I've checked all my soldering and it all looks and feels fine.

What do I check now?

All help is very much appreciated.
  Reply With Quote
Old 24th August 2015, 02:08 AM   #2
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Location: Upper midwest
Quote:
Originally Posted by Bonesurfer View Post
The 2 power tubes glow, but only one preamp tube glows.
Trace out the heater wiring very carefully. The socket with no heater glow is wired wrong.
You can use a DVM to measure the AC voltage on the heater tube pins.
  Reply With Quote
Old 24th August 2015, 02:14 AM   #3
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Moving to I&A since this is a guitar amplifier.

Recheck for broken wires and cold solder joints, bad socket pin?
__________________
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 24th August 2015, 02:15 AM   #4
diyAudio Member
 
Join Date: Aug 2015
The weird thing is that it worked perfectly after the course, I drove home (amp in suitcase flat on the floor of the car- no movement- it was also on a soft blanket to give it some 'suspension'), then it didn't work, so it had been wired correctly at one point.
How exactly do I measure the AC voltage on the heater tube pins?
  Reply With Quote
Old 24th August 2015, 02:17 AM   #5
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Please post more details, schematic [hand drawn or excerpt, plse do not post copyrighted materials here] and pictures of amp showing internals.
__________________
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 24th August 2015, 02:17 AM   #6
diyAudio Member
 
Join Date: Aug 2015
Also with soldering- all the joints seem to be holding solidly but I know that doesn't always mean a proper connection. Is there a way to visually see a bad solder connection?
  Reply With Quote
Old 24th August 2015, 02:19 AM   #7
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Quote:
Originally Posted by Bonesurfer View Post
The weird thing is that it worked perfectly after the course, I drove home (amp in suitcase flat on the floor of the car- no movement- it was also on a soft blanket to give it some 'suspension'), then it didn't work, so it had been wired correctly at one point.
How exactly do I measure the AC voltage on the heater tube pins?
Do you have a digital multimeter, and what tubes specifically are used?
__________________
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 24th August 2015, 02:21 AM   #8
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Quote:
Originally Posted by Bonesurfer View Post
Also with soldering- all the joints seem to be holding solidly but I know that doesn't always mean a proper connection. Is there a way to visually see a bad solder connection?
Sometimes obvious, sometimes not, reheat both filament connections.. If you have a meter check for continuity at the filament pins with the tube removed. You should have a very low resistance if the pins are still properly connected to the transformer filament winding.
__________________
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 24th August 2015, 02:23 AM   #9
diyAudio Member
 
Join Date: Aug 2015
Yes I have a digital multimeter.

The tubes are russian- all I know is the code on the side is 6H2n (although the N looks like a russian symbol) then below that is 08-83
  Reply With Quote
Old 24th August 2015, 02:29 AM   #10
diyAudio Member
 
Join Date: Aug 2015
When you say check for continuity at the filament pins...(sorry for the complete novice questions by the way)...is that checking the resistance from pin 1 to pin 2 and then through each of the 9 pins?
  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
Old fire bottles. Kindhornman Tubes / Valves 4 30th December 2012 02:42 AM
Short wave Valve transmittor :) what valve is best? sco1t Everything Else 89 23rd November 2012 08:42 PM
Which way to fire my sub? Gorbee Subwoofers 24 12th September 2006 12:59 AM
Amp on fire Ford_V6 Solid State 12 2nd April 2003 12:27 PM


New To Site? Need Help?

All times are GMT. The time now is 02:31 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
Wiki