Saturday, November 19, 2011

Daewoo TV DTQ-2072 repeated blowing of fuse

Where can the problem be if the main fuse in the TV power supply blows fuse repeatedly?
This was a problem I have encountered with a Daewoo TV model# DTQ-2072. The fuse blows even when the IC regulator  STR-59041 has been replaced. To isolate the cause of the problem, I replaced the fuse again and disconnenected the PTC thermistor on board location RH02.
I plugged the set to AC outlet and powered up the set from standby. The picture and sound came up but the picture has color smears(dynamic misconvergence) on the sides of the screen - a result of disconnecting the thermistor which passes momentary current to the degaussing coil.
An ohmmeter check on the thermistor shows that it has developed a higher resistance. Opening the plastic case of the PTC thermistor revealed that the thermistor discs are burnt.
Replacing the PTC thermistor eliminated the  color stains on the picture and solved the problem of  blowing of fuse.

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