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Message body Emoticons View more Emoticons	Font colour: Default Dark Red Red Orange Brown Yellow Green Olive Cyan Blue Dark Blue Indigo Violet White Black  Font size: Tiny Small Normal Large Huge Close Tags [quote="torbjorn"]Make sure that there are no shorted turns or any other defects in the transformer. Of cours, there are probably no specifications available for it, but you could de-solder the transformer and measure the inductance of the primary winding, then compare that to the transformer of an ATX power supply of roughly the same wattage. If you have a LCR meter with the option of measuring at different frequencies, then a sure sign of shorted turns is that you get very different inductance readings when changing the frequency from, say 1 kHz to 10 kHz. Also, check out any snubber networks (resistors, capacitors, diodes) that might be fitted across the primary winding or the switching transistors. Make sure that any current measurement shunts (low-R resistors in series with the emitter of any of the switching transistors) are ok. Try running upp the TL494 without applying mains power to the unit (supply it from a bench power supply) and make sure that the clock oscillator is running at the correct frequency, that there comes a square wave at both driver outputs and so on.[/quote]
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