Help with Shorted Xformer - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

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 27th June 2004, 04:36 PM   #1
lgreen is offline lgreen  United States
diyAudio Member
 
lgreen's Avatar
 
Join Date: May 2003
Location: San Diego, USA
Default Help with Shorted Xformer

I believe that I accidently punctured a rather large toroid, about 400VA with a teeeny tiny puncture. The primary now seems shorted to the secondary, since with no load (meaning nothing connected to any of the secondaries) the transformer hums loudly and draws enough current to blow a 6A slow blow fuse immediately. The puncture was probably caused by a screwdriver, so its near the surface under the wrapping and very small, I think one primary winding contacts one secondary winding, shorting out the primary.

Is this something that can be fixed, if so how would you recommend going about the fix?
  Reply With Quote
Old 27th June 2004, 04:58 PM   #2
diyAudio Member
 
Join Date: Dec 2001
Location: South Sweden
First, measuring with a multimeter tells if you really have a short circuit between primary and secondary. I have never had this type of accident, and I have aswell run screwdrivers through the insulation ( but then the secondary was only damaged)

Ususally it is difficult to cause shorts this way, in my experience, since there is always insulation tape stuck in between, and the wire itself is insulated with a thin layer of laquer, that prevents contact. It is sort of self healing when the insulation tape is damaged (not in the real sense). Once I wanted to measure on the primary, and used a sawing needle to puncure through insulation in between secondary turns, and boy , I had to punch hard to get a contact at all.

You could also have casued a short between two secondary turns. This is more likely, and is almost impossible to measure with a multimeter, since the secondaries are in itself low ohmic.

If you remove the outermost layer of tape from the transformer at the point where the screwdriver hit, try to pry the secondary windings apart and se if you can find any damage to the insulation on the primary. A visual inspection always helps.
This could also lead to a possible short on the secondary to break up.

And for gods sake, remove it from mains voltage when doing this!

If it is a short circuit on the primary, the only way I can think of fixing this if it is a is by unwinding the secondary, reinsulate the primary, when making sure that the turns of the primary dont touch each other. Then rewind the secondary back on. Considering the labour for this( it is a lot!) , and also the fact that the transformer insulation can no longer be guaranteed, I would recommend to scrap it. it is not that expensive to risk working with mains voltage on a transformer .


Conclusion.
If it is on the secondary it is fixable. If it is on the primary, use it as a boat anchor.

good luck

/rickard
__________________
listen! Can you hear that ...
  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
X-5 shorted center channel ROLIKOV Pass Labs 2 31st October 2008 06:39 PM
shorted out deck??? new one Car Audio 6 22nd June 2008 01:09 PM
Pearl shorted...please help me out of this! h_a Pass Labs 28 4th June 2007 02:55 PM
How to determine a tube is shorted? Bing Yang Tubes / Valves 8 28th April 2007 05:03 PM
shorted turns in primary? mrshow4u Solid State 15 12th September 2006 05:09 PM


New To Site? Need Help?

All times are GMT. The time now is 09:20 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