Overheating transformer

Previously Geoff Harris <geoffharris RemoveThis @yahoo.co.uk> wrote:
> Someone threw a blanket over the transformer for my laptop. Some time later
> the monitor picture began to vary in brightness. I removed the blanket and
> found that the transformer was extremely hot. In fact, the label on it had
> got stuck to the PVC-covered armchair it was resting on. I disconnected the
> transformer, let it cool down, and now I've reconnected it again. It seems
> to be all right, but is there a chance of a delayed reaction, or a fault
> developing later?

There is. One thing is significantly reduced lifetime. However, if you
could still touch it without getting burns, it was below something
like 62C, and is likely ok. Even if it was damaged, the only likely
failure mode is it dying. A fire is extremely unlikely, and you
are certainly not the only one with an incident of this type.
Since these things must not burst into flames on overheating,
the manufacturer would have issued a recall if the internal
protection circuitry had failed in the past. So I think this is
a "you may loose it, but otherwise don't worry" in the worst case.

Arno
 >> Stay informed about: Overheating transformer 

Arno Wagner wrote in news:637vl3F26d4peU1@mid.individual.net
> Previously Geoff Harris <geoffharris.DeleteThis@yahoo.co.uk> wrote:
> > Someone threw a blanket over the transformer for my laptop. Some time later
> > the monitor picture began to vary in brightness. I removed the blanket and
> > found that the transformer was extremely hot. In fact, the label on it had
> > got stuck to the PVC-covered armchair it was resting on. I disconnected the
> > transformer, let it cool down, and now I've reconnected it again. It seems
> > to be all right, but is there a chance of a delayed reaction, or a fault
> > developing later?
>
> There is. One thing is significantly reduced lifetime. However, if you
> could still touch it without getting burns, it was below something

> like 62C,

On the outside.

> and is likely ok.
> Even if it was damaged, the only likely failure mode is it dying.

Clueless.
It's a switching power supply with voltage up to 400 Volts in there.

> A fire is extremely unlikely,

More clueless. That depends on whether the plastic is flame retardant.
That the label came off doesn't bode well for the overall quality of
that thing.

> and you are certainly not the only one with an incident of this type.
> Since these things must not burst into flames on overheating,
> the manufacturer would have issued a recall if the internal

> protection circuitry had failed in the past.

Which apparently it has already. It's not normal for a label to shed.

> So I think this is a "you may loose it, but otherwise don't worry" in the
> worst case.

That depends on whether the switching PS or the Laptop is fitted with
an overvoltage protection that takes out any fuse before more damage
occurs.

> Arno
 >> Stay informed about: Overheating transformer