GSG problem - diyAudio
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 16th June 2012, 03:25 AM   #1
diyAudio Member
 
Join Date: Sep 2011
Default GSG problem

Hello everyone!
First time posting, I just built a GSG 6b4g.
first try, the rectifier tube turned bright orange with purple haze....
tried 3 tubes, same results.
So I checked the volages for the 6ax5gt
Pins 2 and 7 4.3v
Pins 3 and 5 344v
Pin 8 is not connected to anything, though the voltage check up list wants it at 333v, I got wild swings and had to cut power as the tube was loudly complaining ( on the kitchen table not hooked to anyting)
What could be wrong?
Richard
  Reply With Quote
Old 16th June 2012, 07:37 AM   #2
djn is offline djn  United States
diyAudio Member
 
djn's Avatar
 
Join Date: Oct 2004
Location: Waterford Michigan
Best to start tracing the wiring with a very open mind. I built a phono pre once that was red plating only one of the tubes. I traced that amp for a week and could not find the problem.....because.....I assumed I did everything right. A friend came over and took a minute to see that I had the B+ hooked up to one of the heaters on the tube.
__________________
My "Art" website http://home.comcast.net/~djnagle/site/
  Reply With Quote
Old 16th June 2012, 03:46 PM   #3
diyAudio Member
 
Join Date: Sep 2011
Thanks, I am new at this.
I wired the amp following pix posted on line, so I will trace what comes out of the Tx and where it goes.
Richard
  Reply With Quote
Old 16th June 2012, 06:06 PM   #4
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Pin 8 (cathode) should normally be connected to the first PSU cap, +ve side. Have you grounded pin 8 instead, or got the cap the wrong way round? The orange anode and lowish heater voltage suggests an overload. If you left it like that it would be a race between the 6AX5 and the transformer to see which one blinks first and lets out the blue smoke.
  Reply With Quote
Old 16th June 2012, 08:52 PM   #5
diyAudio Member
 
Join Date: Sep 2011
Thanks, all caps are properly installed, I will remove the board and see if there is a trace from pin 8 on the other side.
Will let you know
  Reply With Quote
Old 16th June 2012, 09:04 PM   #6
diyAudio Member
 
Join Date: Sep 2011
Pin 8 is connected to nothing at all !!
  Reply With Quote
Old 16th June 2012, 10:24 PM   #7
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Are you counting the pins the right way?
  Reply With Quote
Old 16th June 2012, 10:51 PM   #8
7N7 is offline 7N7  United Kingdom
diyAudio Member
 
7N7's Avatar
 
Join Date: Jan 2003
Location: England
Quote:
Originally Posted by djn View Post
Best to start tracing the wiring with a very open mind. I built a phono pre once that was red plating only one of the tubes. I traced that amp for a week and could not find the problem.....because.....I assumed I did everything right. A friend came over and took a minute to see that I had the B+ hooked up to one of the heaters on the tube.
I know what you mean: I recall an E88CC that survived with 300V on one of its grids... Today a screwdriver slipped and the red LED on a cascode CCS went out. I removed the board, replaced everything and it refused to behave - sinking too much current. Finally I gave up. ignored the calculations and removed a 150-ohm resistor and replaced it with a 220 ohm one. Perfect. Funny, the other board which is absolutely identical still has its 150-ohm resistor and works perfectly and to spec.
Sometimes you have to give up!

Paul
__________________
Plug them in and light them up
  Reply With Quote
Old 17th June 2012, 12:37 AM   #9
diyAudio Member
 
Join Date: Sep 2011
Pins are numbered, and the socket is soldered in the proper direction.
I tested the 180 ohm resistor at R17 a and b and read 90 ohms on each, is that normal?
Another board is comming in the mail, maybe 2 is the charm....
  Reply With Quote
Old 17th June 2012, 02:39 AM   #10
diyAudio Member
 
Join Date: Sep 2011
Hooray!
I went over the schematic, and decided to ground the board from J6 to chassis and IEC plug.
It is working fine now, but I stay close.
On most pix I saw no one grounding the board.
Thanks for your support
  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
Is this a problem or not? chipper Car Audio 7 18th May 2011 09:34 AM
Got a Problem, Need Some Help odysseybmx414 Car Audio 7 22nd July 2010 04:12 PM
Need some help with such a problem... beauty_divine Digital Source 2 20th November 2007 07:08 AM
problem Ricky Introductions 4 16th September 2005 08:53 PM


New To Site? Need Help?

All times are GMT. The time now is 06:24 AM.


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