Help! Advice?

[jaygon02]

Hi,

I'm wondering if anyone can shed any light on a problem I've run into and suggest some solutions as my knowledge is very rudimentary at best.

I have a European 16mm projector I just purchased 2nd hand here in Sydney. The guy I bought it from had it plugged into a 240 to 220v transformer and suggested it's safer if I use the projector with this.

We tested it before buying and all looked good. Just now when I've plugged in at home I connected an audio cable out of the projector and into a brand new 4 channel mixing desk and fired it up. Within seconds the channel on the mixer started smoking. I quickly turned it off but it's now fried.

Why would this be the case? What have I done wrong? And I'm unsure about using the projector now.

Upon reflection I did wonder why he was using the transformer in the first place so I then did the same test without using the transformer and tentatively plugged the audio back into a good channel on the mixing desk and alas it all seems to be working fine.

So my questions are how and why did I fry my channel on the mixing desk?
And is it safe to use this Euro projector straight into the socket here in Australia?

Cheers

 

[(*steve*)]

Does it have a 2 pin plug that can be connected either way around?

 

[jaygon02]

Yes

 

[(*steve*)]

It is possible that a fault in your device has caused a short between an input power connection and the internal low voltage power supply or ground. If so, then reversing the power connector could change that from a relatively benign connection to ground to a far more dangerous connection to live.

The 240 to 220 volt transformer is likely to be an autotransformer and there are traps with using these also. If it can be connected either way around then you can connect it so the whole circuit is floating above mains neutral. A fault can also cause the full mains voltage to be present at the output.

As to whether the device can be connected to 240V, that's difficult to say. Generally it is, but if it has a 220V lamp in it, it's lifetime week be shorter (and they are already pretty short).

 

[jaygon02]

Thanks for the reply. The lamp is 24v, 250 watt