GTA 300B SE Mk.II Power Transformer - 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 17th December 2007, 01:50 PM   #1
diyAudio Member
 
korneluk's Avatar
 
Join Date: Jan 2005
Location: South Florida
Default GTA 300B SE Mk.II Power Transformer

Folks,

I have a 300BSE Mk.II (6SN7, EL34, 300B) that instantly trips the breaker when it is turned on.

With the power switch on, I measure 1.6 ohms across the hot and neutral AC pins. There are no shorts between hot/neutral and the ground pin, and the internal fuse F1 on the PCB is not blown.

I am afraid that my power transformer primary may be shorted. Can someone ohm out their unit and confirm my measurements?

TIA,

-- josť k.
jose_korneluk AT bellsouth.net
  Reply With Quote
Old 17th December 2007, 03:03 PM   #2
diyAudio Member
 
dshortt9's Avatar
 
Join Date: Apr 2001
Location: Milwaukee, Wisconsin
I have a power transformer from that amp. I removed it and do not remember which leads are the primary. If you can tell me which leads to check I can do so.
  Reply With Quote
Old 17th December 2007, 03:09 PM   #3
diyAudio Member
 
korneluk's Avatar
 
Join Date: Jan 2005
Location: South Florida
The primary are four black leads (connected in parallel for 120VAC) that do not have a center tap. There is another winding that comes out the same side as the primary which has a center tap for the 5V rectifier tube filament. The ten thicker leads on the other side are all secondaries.

BTW, if you do not plan on using that tranny, I'll gladly buy it off you. Please PM offline.

Thanks and best regards,

-- josť k.
jose_korneluk AT bellsouth.net
  Reply With Quote
Old 17th December 2007, 03:41 PM   #4
diyAudio Member
 
dshortt9's Avatar
 
Join Date: Apr 2001
Location: Milwaukee, Wisconsin
The two primaries read 2.0 ohms seperately or 1.0 ohm in parallel, right at the transformer. You probably have an extra 0.6 ohm in the power cord and connections.
My transformer has a shorted secondary which is why I removed it in the first place.
  Reply With Quote
Old 17th December 2007, 05:09 PM   #5
kmtang is offline kmtang  Canada
diyAudio Member
 
kmtang's Avatar
 
Join Date: Nov 2004
Location: Vancouver
Remove all the tubes and see if it can be powered up first.

In case it still blows the fuse, surely there's something wrong with the power transformer.

Johnny
  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
300B Transformer temperature peter7 Tubes / Valves 7 27th September 2008 04:12 PM
TubelabSE 300B power transformer ? abacus Tubes / Valves 11 25th September 2008 01:47 AM
SJS SE 300B with Interstage Transformer Mk2 DVDHack Tubes / Valves 29 20th August 2008 11:52 AM
tubelab SE 300b power transformer Dhoff Tubes / Valves 27 14th March 2008 04:56 PM
Best output transformer for 300B hnb2907 Tubes / Valves 8 4th December 2007 04:14 PM


New To Site? Need Help?

All times are GMT. The time now is 10:36 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