Hi guys and electricians,

I have a defunc 6631 trafo. :-(
It looks like it has seen very little use, but nevertheless it doesnt have any output, nor does the small lamp light up.

I removed the splits and opened the casing, and started meassuring with my simple hobby-multimeter. (Please, no comments about how dangerous this is, and that I shouldnt be doing this, etc...)

I found that a small thermo-breaker (on the primary side I think; the one with some 10 windings with a thin wire) was BROKEN. Looked like the thermo-wire had burned.
I fixed that removing one winding of the thermoelement, re-connecting the breaker again.

So far so good; I could now see that current was flowing. (a small spark when connecting the breaker) When the breaker is open, I meassure some 10V AC across it. A little strange no, if this is indeed the primary side???

But still no output on the secondary side. Nothing at all!

I checked the other thermal breaker (the one with a thick wire and only two windings) and it looked ok. -at least there was no tension drop across it. (in fact I doubt current is flowing in the secondary side at all?!)

I checked visually and by pulling (softly) on all the wires going to the coils, and didnt find anything broken or loose.
Quite the contrary; everything looked good and clean and new.

What can be the problem? -is there any specific test or meassurement I can make, in order to find the problem, fix it, and get this unit going again???

Hi Henrik,

It sounds to me like you might have a short in your primary or secondary coils, which caused the thermal trip to blow, but it's dificult to tell from your measurements. Is there any evidence of overheating on the coils? Was there any smell of burning when opened?

Sounds like the safety device is broken.
Don't take any risk, buy a new one.

Yoooooooo Henrik,

Get a new one, this IS in fact dangerous [}:)]

In Holland you can buy a new white trafo (32va) out a starterkit for 20 euro.

Addition: I also recently fried a decoder in analog mode using an old blue transformer. These old transformers sometimes pump out too many volts, esp. on the reversing impulse. Yet another reason to "go white".

Guys,

Thanks for your comments.
I KNOW of course that all of you are RIGHT aboutit not being worth the risk or effort to fix it (hence my "please no comments about...") ;-)

I looked at a white second-hand trafo in Denmark during the summer-holidays, but 30,- Euros seemed a little steep. (Now I wish I had bought it anyway ;-)

@DasBert33; It must be analog!!!

@Others; I dont use Ebay, and I dont have any shops close by, hence my desperation in trying to fix it.

I will try NOT to be tempted anymore to try and fix it...

@hmsfix; Thanks for your specific help. -But it makes it more difficult NOT to keep investigating... ;-)

Just for fun, follow Hans Martins advice, and measure the resistance in both primary
and secondary coil, and the 2 breakers, and then tell us your result.

Remember to disconnect first!

Per.

Okay I will try to do it, but now I have to wait until monday to bring home a decent multimeter...