Re: Thermal Fuse, Transformer

In article <mWaXk.6949$as4.4604@xxxxxxxxxxxxxxxxxxxx>, "Mark D. Zacharias" <nonsense@xxxxxxxxxxxx> wrote:

"Stevie D" <steve.dumouchel@xxxxxxxxxxxx> wrote in message
news:23d1475f-7df1-4626-a67c-2a9945c1a18b@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Nov 24, 7:10 pm, Chris Hornbeck <chrishornbeckremovet...@xxxxxxx>
wrote:
On Mon, 24 Nov 2008 14:21:01 GMT, zekfr...@xxxxxxxxxxxxxxxx (GregS)
wrote:

Just bypass it.

Please, please don't do this.

Thank you,
Chris Hornbeck

Thanks all for the advise. Here's what I've done; replaced with the
171 degrees f thermal fuse, let it sit, turned on with volume at zero
and waited... It took a few hours, then I touched the transformer, it
was hot to the touch, hot enough to worry me. I turned the receiver
off and waited two hours. The xfmr was still warm. Under "power on"
condition, it was almost unbearable to keep my hand on it, this is my
litmus test, and I considered it a fail! The fuse held up but my
customer is not getting this back until I undo my repair and recommend
he buy a new one.
Cheers

If it's getting that hot just sitting there turned on, it has some other
problem. A shorted diode in the power supply area for example. A voltage
regulator could be sitting there happily putting out 12 volts DC even with a
large AC component going in. You might never hear it or trigger the
protection circuit, but the transformer would get hot like that.

Actually had this happen once, in fact.

Mark Z.

I have seen bad transformers with high loss such as a shorted turn.
When the transformer overheated the short may have appeared
or it may have just decided to short for no other reason.

greg
.

Relevant Pages

  • Re: Home made AC-AC power supply question
    ... It is not short circuit proof and it does not have a thermal fuse. ... ** That little transformer is kinda special, ... A inherently short circuit proof transformer is one that by design will NOT ... any possibility of the primary winding contacting the iron core & frame or ...
    (sci.electronics.basics)
  • Re: Dead transformer in UPS
    ... "There may be a thermal fuse buried under the outer layers of the transformer which may have blown. ... If its a metal incased transformer you have to take the clam shell shield off of it before you begin. ... If the leads measure open, look where the leads go into the transformer body. ... You need to cut away this plastic carefully with a Xacto knife or such and follow the lead wires down to the core. ...
    (sci.electronics.repair)
  • Re: Thermal Fuse, Transformer
    ... On Nov 24, 7:10 pm, Chris Hornbeck ... 171 degrees f thermal fuse, let it sit, turned on with volume at zero ... If it's getting that hot just sitting there turned on, ... A shorted diode in the power supply area for example. ...
    (rec.audio.tech)
  • Re: Thermal Fuse, Transformer
    ... I don't understand the rationale for thermal fuses in transformer ... Is there anyone who can supply a detailed argument why the thermal fuse ... I refused to sell some of the Sansui ... stereo amplifier that did it. ...
    (rec.audio.tech)
  • Re: VA of unknown transformer
    ... By the time that transformer has got hot enough on the outside for you to be ... getting worried, the windings in which the thermal fuse is buried, if indeed ... your tuner, the current demand by the circuitry, will be pretty steady once ... or so from each winding, ...
    (sci.electronics.repair)