How to clean transformer laminations? - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 12th February 2012, 03:19 AM   #11
diyAudio Moderator
TonyTecson's Avatar
Join Date: May 2003
Location: Palatiw, Pasig City
Originally Posted by rcbuck View Post
I will try the dip and wipe. I don't need to remove all the wax, just enough to make re-assembly easier.

This is not a transformer designed for high quality. I am making a test transformer for a 70 volt system at 35 watts. Input will be 40 watts at 6.5 ohms. I figured 5 watts of transformer loss. The frequency range will be from 200 Hz to about 5 KHz. I did all the winding calculations based on a low frequency of 200 Hz.

It was a cheap Chinese 60 watt power transformer. As a result, the size of the core is larger than needed for 40 watts of audio with a low frequency of 200 Hz. Once I have it re-assembled I will drive it with a 1000 Hz tone. If I hear the core singing I will heat the transformer in the over at 350 for a couple of hours which should melt enough of the remaining wax to quieten it down.
sounds can also use popsicle sticks, shaped to wedge between the core and the coils if there is can even dip it in a polyurethane or shellac varnish if you wish.....
planet10 needs your help: Let's help Ruth and Dave...[B
  Reply With Quote
Old 12th February 2012, 03:35 AM   #12
diyAudio Member
Join Date: Jul 2010
Location: Stewartsville, NJ
String with wire accross a pot and place in the oven and let drip until clean.
  Reply With Quote
Old 12th February 2012, 07:10 AM   #13
! is offline !  United States
diyAudio Member
Join Date: Jun 2005
Location: Midwest
laminations are about magnetic field so don't worry about perfect electrical contact. Putting them together with tension pushing them towards each other while heating to a temperature sufficient to melt the wax should suffice.

Suggestion - put a few c-clamps on them and heat in an oven past the melting point. If it comes out of the oven with the C-clamps loose, lather, rinse and repeat.
  Reply With Quote
Old 12th February 2012, 11:20 AM   #14
AndrewT is offline AndrewT  Scotland
diyAudio Member
Join Date: Jul 2004
Location: Scottish Borders
Rusty lamination is the insulation.
It is not there as a result of overheating.

The insulating layer is created during manufacture.
regards Andrew T.
Sent from my desktop computer using a keyboard
  Reply With Quote
Old 13th February 2012, 02:01 AM   #15
rcbuck is offline rcbuck  United States
diyAudio Member
Join Date: Feb 2010
Location: Phoenix, AZ
I managed to get the transformer rewound as an audio transformer. I couldn't hang the laminations because they don't have holes in them. It would have been too difficult without the holes. I finally settled with just reheating the laminations on a flat piece of metal with the torch. This leveled the wax enough so I was able to get all the laminations except for one E piece back into the plastic bobbin.

The transformer performs more or less as designed. Driving it with a 16.2 volt 1000 Hz signal produces 70.7 volts out. At 5 KHz the same drive signal produces 65 volts out. So I have some high frequency roll off. The loss probably is due to not enough inductance in the 6.5 ohm windiing.

My next test will be to find a slightly larger core and re-calculate the winding data and give that a try. This is all being done just to advance my knowledge of transformer design. I am using the information from "Practical Transformer Design Handbook" by Eric Lowdon. The book was published in 1980 and is now out of print. It has a wealth of practical knowledge. No information about SMPS but it does give design info for 400 Hz and 1000 Hz transformers.
  Reply With Quote
Old 22nd April 2012, 06:46 AM   #16
diyAudio Member
Join Date: Feb 2009
Location: Minneapolis, MN 55404
It's the oxide on the steel laminations that is primarily responsible for reducing the eddy currents. But you may also use varnish or wax to improve the insulation between the laminations. However, in order to be effective at reducing eddy currents the varnish needs to be applied and cured BEFORE the laminations are put together.

The main reason for adding varnish or wax to an inductor, after it is assembled, is to aid in the insulation of the windings. The varnish also serves to insulate any nicks on the enamel of windings. Varnish or wax also makes for a quieter inductor. Driving a wedge between the coil form and the center leg of the core, tightly bolting the laminations together (With insulating shoulder washers over the bolts to reduce eddy currents.) and vacuum varnishing the inductor, results in the quietest inductor and also one that can withstand the highest voltages.

Welding a bead across the corner of the laminations is to provide a conductive ground path for safety, just in case a winding shorts to a lamination. That way any current and voltage is shunted to ground. People have been electrocuted when they have touched non-welded laminations that were shorted to the windings. The welding does cause a slight increase in eddy currents, however, it is considered a small price to pay for safety.

If you have removed all of the wax from the laminations, at the very least you can dip the transformer in hot varnish. Better still if you can find a vacuum pump and a container to hold the vacuum around the inductor when you dip it in varnish. But be sure you find a suitable varnish.

Scott Novak
  Reply With Quote


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 it OK to drill mounting holes in transformer laminations? Derekva Tubes / Valves 7 17th April 2011 06:37 PM
EI laminations in Europe overdrajv Parts 2 27th February 2009 08:09 PM
I Need Nickel Iron Laminations and Bobbins ! Nikolas Ojala Swap Meet 3 7th April 2008 03:57 PM
A basic question regarding transformer laminations KT Tubes / Valves 4 18th December 2006 08:18 PM
E/I transformer laminations; why? carpenter Pass Labs 41 19th September 2005 10:05 PM

New To Site? Need Help?

All times are GMT. The time now is 09:46 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