Transformer substitution question
 

Garage door opener power supply transformer has an opened primary. It's
actually a burnt coil wire right on the pin. I did manage to solder it
back on but I'm worried it may fail again.

It's a 38V CT. Of course I can't find the *exact* replacement, but can
I use a 36V CT ?

Thanks,

Yes you should be OK ..

kip
wrote in message
oups.com...
Garage door opener power supply transformer has an opened primary. It's
actually a burnt coil wire right on the pin. I did manage to solder it
back on but I'm worried it may fail again.

It's a 38V CT. Of course I can't find the *exact* replacement, but can
I use a 36V CT ?

Thanks,

"kip" writes:

Yes you should be OK ..

Or, have confidence in your repair. If it failed at the pin, it was a
solder problem, not something more ominous.

If the new soldering was done properly, it should last. If it were something
else, it's likely the failure would be inside.

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kip
wrote in message
oups.com...
Garage door opener power supply transformer has an opened primary. It's
actually a burnt coil wire right on the pin. I did manage to solder it
back on but I'm worried it may fail again.

It's a 38V CT. Of course I can't find the *exact* replacement, but can
I use a 36V CT ?

On 24 Aug 2005 09:13:10 -0700, wrote:

Garage door opener power supply transformer has an opened primary. It's
actually a burnt coil wire right on the pin. I did manage to solder it
back on but I'm worried it may fail again.

You better be worried about a fire hazard !
There usually is a good reason for a transformer to burn it's
coil.

There is nothing basically wrong with resoldering the part, but
_please_ make sure that there is some thermal cutout device in
the circuit. (And that it is thermically coupled to the
transformer.)

--
Kind regards,
Gerard Bok

On Wed, 24 Aug 2005 17:57:24 GMT, (Gerard Bok) wrote:

On 24 Aug 2005 09:13:10 -0700, wrote:

Garage door opener power supply transformer has an opened primary. It's
actually a burnt coil wire right on the pin. I did manage to solder it
back on but I'm worried it may fail again.

You better be worried about a fire hazard !
There usually is a good reason for a transformer to burn it's
coil.

There is nothing basically wrong with resoldering the part, but
_please_ make sure that there is some thermal cutout device in
the circuit. (And that it is thermically coupled to the
transformer.)

Don't most/all transformer primaries have this?

Tom

On Wed, 24 Aug 2005 20:18:13 GMT, Tom MacIntyre
wrote:

On Wed, 24 Aug 2005 17:57:24 GMT, (Gerard Bok) wrote:

On 24 Aug 2005 09:13:10 -0700, wrote:

Garage door opener power supply transformer has an opened primary. It's
actually a burnt coil wire right on the pin. I did manage to solder it
back on but I'm worried it may fail again.

You better be worried about a fire hazard !
There usually is a good reason for a transformer to burn it's
coil.

There is nothing basically wrong with resoldering the part, but
_please_ make sure that there is some thermal cutout device in
the circuit. (And that it is thermically coupled to the
transformer.)

Don't most/all transformer primaries have this?

They should have. (But I wouldn't bet on it.)

Depending on where you live, extra care should be taken when you
do the repair yourself.
If there is a fire, an insurance company may require proof that
you didn't tamper with any fireprotection that was present in the
device.

--
Kind regards,
Gerard Bok

Thanks for all the replies. What made me decide to replace the
transformer was that I just didn't think the initial repair would hold,
it was rather delicate to do. I had resoldered the tiny copper strand
back on the solder tab, I think the strand still had some
lacquer/glue/adhesive on it after attempting to clean it, and had less
than a millimeter of play; I just wasn't satisfied I had enough contact
surface and it was difficult to properly and cleanly wet the joint.
Ugh.

I ended up installing the replacement transformer, a 36v CT 1A unit
riveted outboard on the chassis, the original being 38v CT 500mA, and
cleanly tiewrapped the cabling to an existing harness and onto the PCB.

I measured the same voltages on the various screw terminals as with the
previous (flaky) transformer.

The fuse hasn't blown yet, and I have a fire extinguisher handy :-)

Thanks to all,