How do I remove windings from this transformer?

[Jackal66]

Hello,

Al mentioned the other day that he has successfully removed windings from a laminated transformer.

I would appreciate it if you would coach me on how to do this.

Here is some pics of the transformer. I carefully removed the outer protective film and some of the fabric wrap.

For this I used a Popsicle stick, wooden paint stirring stick, and a plastic putty knife.

The varnish is critical and you need to be careful not to nick it.

It appears the power in (primary) is the outer winding. It has (2) coils connected to it shown in the picture. There is plenty of room for careful work.
The wire gauge looks about .090 thou diameter. The varnish is too thick to measure.

[Jackal66]

Here is the rest of the pics.

The dollar bill shows the physical size of the transformer.

No wonder they charge $100 to ship one of these across the US.

Thanks for your help,
JAckal

[mike_Kilroy]

u seem on the right track. as Al has removed windings, I have added windings to a xfmr to get more voltage for my 2 meter 120 watt amplifier. I wound 3 more turns of couple #12 wires in parallel (I didnt have any thicker wire at the time) around my 1 ph xfmr and IIRC increased output voltage from 12v to 13.5v. be carefull and go for it!

[Al_The_Man]

Originally Posted by Jackal66 Hello, Al mentioned the other day that he has successfully removed windings from a laminated transformer. I would appreciate it if you would coach me on how to do this. Here is some pics of the transformer. I carefully removed the outer protective film and some of the fabric wrap. It appears the power in (primary) is the outer winding. It has (2) coils connected to it shown in the picture. There is plenty of room for careful work. The wire gauge looks about .090 thou diameter. The varnish is too thick to measure.

I believe you mean the secondary is the outer winding, this is usually the case and appears so in the one you show.
Hopefully the varnish or shellac is not too thick and the idea is to take the outer turns off as carefully as possible.
It is hard to do on a square laminated, but if you first wind ON say 10 turns of small gauge wire on as a means to determine the turns/volt, power up the transformer and measure the voltage on the 10t. it will get you a fairly accurate idea of how many to take off of the secondary.
If you want to re-coat the winding when you are done, you can use Conformal Coating available by the 1 litre can.
Al.

[Jackal66]

Thanks guys,

Al,

I see what you, mean. The H1- H4 are the inputs ( Primary).

The secondary is the outer windings that are connected to the lead , in the close up pic.

It just threw me at first, because the lead wire that goes to the double wire on the coils, is thicker than the H1-H4 wires.

For adding the new wraps, can I use solid household wire?

Maybe strip the sheath on some Romex type 14 ga.and take out one wire. Then use about 4+ wraps and leave the insulation on the wire for protection??


Thanks,

JAckal

[Al_The_Man]

You need insulated wire, and #14 is a bit larger than you need just to get the T/V.
It can be small gauge stranded if necessary as there will not be a load present on the winding.
A stripped multi conductor cable will service.
Al.

[vger]

If you would rather use enameled magnet wire (like the wire on the transformer now) you might try getting some from a local electrical motor repair shop. They use a lot of it and will probably sell / give you enough to do your rewind. Just be carefull not to scrape the insulation off as you are winding. Give yourself lots of room and cover the inner lamination edges (sharp) with a couple of layers of masking tape that can be removed when you are done winding. You might also ask at the motor shop for some of the stuff they use to coat the windings. This keeps the windings from vibrating, making noise, and heating up from the friction created from movement.

Steve

[Al_The_Man]

The alternative to the T/V winding is to simply take off a small number of turns to begin with and then power up and measure the difference, this will tell you the T/V with probably less work.
Al.

[Jackal66]

I found some #10 gauge stranded wire. It was long enough to get (5) turns wrapped real tight on the transformer.

Before it put out 64.9 VAC, now it puts out 75.0 VAC.

So that means each wrap is 2 volts?

On removing the wire to get lower voltage, would removing 5 wraps to lower -10 volts= 55volts x 1.414 rectifier=77.77 new voltage.

My concern is the coil is double wire until it get to the lead wire where both are soldered to the lead.

Since You can't remove 2.5 turns, should I just remove 3 wraps and check it?

Here is a pic of my added wraps:




This pic shows the lead where it connects to the dual wire of the coil. covered in electrical tape.


Thanks,
JAckal

[Al_The_Man]

That's odd, I have seen 2t/V but not the reverse, 2V/t?
I really meant to just wind on the test winding as a separate winding, not put it in series, although that should work, it is usually easier to keep them separate..
At this point, I would take say 5 full turns off the existing secondary and measure the new difference on the old secondary.
Al.

[Andre' B]

Some times it is easier to add turns then to take them off.
In which case you can add the turns but wire them in series but reverse polarity with the existing winding to knock the voltage down.

[Jackal66]

Al,

I figured if you put on 5 turns and it adds X amount of volts, you know the value of each turn at that diameter.

After removing 3 wraps I checked and it had dropped to only 58V.

Removed 4 & 5 and stayed at 58V

By removing the 6th wrap, it now fluctuates from 56.4 to 57.1 volts.

That would give me from 79.7 to 80.7 DC volts.

That should be close enough for the 80V Geckos shouldn't it?

Marcus at Geckodrives told me :

The G320X will work at 80VDC just fine; we use very robust MOSFETs in our drives and de-rate them to 80VDC from about 110VDC to ensure that they will not blow because of an over-voltage.

It's doubtful that my meter is exactly right on anyway.

I may take off another wrap to be safe.

JAckal

Al,

Here's you a beer.

I owe you a keg after all of the help you've given me.

Thanks!!!!!!!