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kroto 12th February 2013 09:03 AM

TDA7294 output stuck to -Vsupply
one of my (the farthest from the fan) TDA7294 output stuck to -Vs, why was that?
is it dead? does anyone have the same experience? :confused:

the heatsink is pretty small but with a fan, and box ventilation is rather small.
VS +/-30Vdc.

and what is the voltage rating of general brown ceramic disc cap, such as this pic?


pacificblue 13th February 2013 05:29 PM

If the input signal does not lead to that, then yes, the TDA is fried.

Mooly 13th February 2013 06:06 PM

The cap is an unknown voltage wise. It could be as low as 16Vdc, more probably 50Vdc but as we don't know for sure....

kroto 14th February 2013 04:58 AM

@pacificblue: no input signal, and no Coupling cap too.

@mooly: that would be unsafe to be used as miller cap then.

thanks all.

Mooly 14th February 2013 06:47 AM

Without knowing the voltage rating I wouldn't use it anywhere that sees more than 16 volts across it.

JMFahey 14th February 2013 06:50 AM

Test it.

JMFahey 14th February 2013 12:56 PM

Not forgetting that small value ceramic caps auch as this one, are usually rated for 500V or even 1 KV.
Never ever saw a 16V rated ceramic , althouh in the highest values (such as 0.1uF ) I have used some 25V rated ones.
You do what you want, but personally *I* would use it and not worry a second.

Mooly 14th February 2013 04:26 PM

I'm thinking it could be like this,

kroto 18th February 2013 07:25 AM

i have been use such ceramic (100pF) for miller at supply 35V with no failure though.

just curious since some friend say most of it rated at 50v and not blow.

daudinhbl 21st February 2013 04:36 PM

Check R 22K from pin 14 (OutPut) to pin 2 (NFB). If you don't connect R feed back, the Voltage at pin output will set to V-.

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