How do I repair my Tube Amp? - 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 July 2013, 06:26 AM   #1
diyAudio Member
 
hydrovac's Avatar
 
Join Date: Dec 2003
Location: hyderabad. India
Default How do I repair my Tube Amp?

Need help in fixing my Tube amp.

Hello everyone,

I really need help. A month ago my cayin MT12A tube amps power transformer failed and stopped functioning.

I tried contacting the manufacturer for support but there is no response. Does anyone have knowledge about these amps. Schematics or at least the transformers secondary voltages so that I can get it wounded.

Any assistance in this regard would be much appreciated. Thanks in advance.

Krishna
__________________
For some people, it's a part of life. For others it's irrelevant.
The mysteries of neurology and how our individual brains function.
  Reply With Quote
Old 17th July 2013, 07:18 AM   #2
diyAudio Member
 
Join Date: Nov 2008
Location: Denmark
I strongly advise that you thouroughly examine that amplifiers circuit for faults and short circuits before you plug in a new transformer, you might risc that you just damage the new one too if you do not locate the source of the first failure.
  Reply With Quote
Old 17th July 2013, 08:24 AM   #3
M Gregg is offline M Gregg  United Kingdom
diyAudio Member
 
M Gregg's Avatar
 
Join Date: Jun 2010
Location: UK
How do you know,

That the transformer is damaged?
What tests have you done?

Regards
M. Gregg
__________________
What is the sound of one hand clapping?
  Reply With Quote
Old 18th July 2013, 11:06 AM   #4
diyAudio Member
 
hydrovac's Avatar
 
Join Date: Dec 2003
Location: hyderabad. India
Hey guys,
Here is the link to the product I am referring to. See if you can make out anything from that.
Zhuhai Spark Electronic Equipment Co.,LTD,-
__________________
For some people, it's a part of life. For others it's irrelevant.
The mysteries of neurology and how our individual brains function.
  Reply With Quote
Old 18th July 2013, 11:59 AM   #5
M Gregg is offline M Gregg  United Kingdom
diyAudio Member
 
M Gregg's Avatar
 
Join Date: Jun 2010
Location: UK
This might sound stupid but,

How do you know the power Transformer is damaged? Have you checked the mains supply to the primary? and the secondary output volts with a volt meter?

If not have you checked continuity and resistance of the windings?

Do you have any power at all to the primary of the power Tx?

What I'm trying to say is HAVE YOU CHECKED THE FUSE...sigh...lol

This looks interesting..
http://www.audiokarma.org/forums/sho....php?p=6951834

Stop and think! Listen to the questions what have you done to prove the Tx is damaged..you keep saying you want to rewind it.
If we know its damaged then OK it needs a replacement or repair.

Regards
M. Gregg
__________________
What is the sound of one hand clapping?

Last edited by M Gregg; 18th July 2013 at 12:11 PM.
  Reply With Quote
Old 19th July 2013, 06:19 AM   #6
diyAudio Member
 
hydrovac's Avatar
 
Join Date: Dec 2003
Location: hyderabad. India
OK,

I disconnected and opened up the transformer, and checked the resistances of prim and sec windings. Primary is showing shorted. (photo)
1 sec shows 36ohms
2 sec 2 ohms
3 sec nothing (open)
What other tests should I conduct, to know the condition of the Xformer.

Thanks

Click the image to open in full size.
IMG_4589 by hydrovac, on Flickr

Click the image to open in full size.
IMG_4590 by hydrovac, on Flickr

Click the image to open in full size.
IMG_4591 by hydrovac, on Flickr

Click the image to open in full size.
IMG_4599 by hydrovac, on Flickr

Click the image to open in full size.
IMG_4600 by hydrovac, on Flickr
__________________
For some people, it's a part of life. For others it's irrelevant.
The mysteries of neurology and how our individual brains function.
  Reply With Quote
Old 19th July 2013, 10:20 AM   #7
diyAudio Member
 
Alastair E's Avatar
 
Join Date: Feb 2004
Location: South Wales
Primarys always show a very low resistance in a test like this!

I would be surprised if the primary was more than say, 15 ohms!

Any fuses blown?

What voltages do you get if primary connected to supply and secondary voltages tested?
--Take care with these tests as mains as well as secondary voltages are capable of Killing Easily!
__________________
Das Beste Oder Nichts
  Reply With Quote
Old 19th July 2013, 10:40 AM   #8
diyAudio Member
 
Join Date: Dec 2012
Location: The Jurassic Coast, England. GB
Send a message via Skype™ to JonSnell Electronic
A DVM is not the best way of measuring the DC resistance of a primary or secondary. Use a moving coil AVO 8 or similar. The resistance will show very low and as the flux builds get higher. If no flux builds, the transformer has shorted turns.
  Reply With Quote
Old 19th July 2013, 12:50 PM   #9
diyAudio Member
 
Alastair E's Avatar
 
Join Date: Feb 2004
Location: South Wales
Quote:
Originally Posted by JonSnell Electronic View Post
A DVM is not the best way of measuring the DC resistance of a primary or secondary. Use a moving coil AVO 8 or similar. The resistance will show very low and as the flux builds get higher. If no flux builds, the transformer has shorted turns.

Hmm--Think you have that the wrong way round!

During this test with something like Avo-8--Which the O/P may not have access to as he isnt in the UK.......

The apparent 'resistance' would appear High, Then will fall as the flux builds.....
--This effect may Not be apparent with some transformers though IME.

Either way--once settled, the DC steady-state resistance will only be a handful of ohms of the Primary....
__________________
Das Beste Oder Nichts
  Reply With Quote
Old 19th July 2013, 01:00 PM   #10
diyAudio Member
 
Join Date: Dec 2012
Location: The Jurassic Coast, England. GB
Send a message via Skype™ to JonSnell Electronic
My mistake, it has been a while.
Yes, the resistance reduces as the field builds. Any moving coil meter will work. I used an AVO as an example.
  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
Tube Amp Repair - SE Michigan kach22i Tubes / Valves 0 23rd March 2012 06:34 PM
Tube Amp (Rivera guitar amp) repair gone wrong ems71 Instruments and Amps 16 24th February 2012 05:09 PM
Tube amp repair hwong Full Range 2 7th November 2008 03:20 AM
Tube amp repair hwong Tubes / Valves 6 7th November 2008 03:16 AM
vintage tube amp repair help adason Tubes / Valves 25 10th December 2006 09:48 PM


New To Site? Need Help?

All times are GMT. The time now is 04:29 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