Sony KV-2964 High pitched sound

[dahbrown]

Hi, I have a Sony KV-2964 that when you turn it on, it makes a high pitched squeal, no picture and audio. Could it be the HOT (shorted) causing the SMPS to make this noise? Without taking out the HOT what checks could I verify to pinpoint this fault?

Thanks
Dave

[torbjorn]

First, check that the horizontal output transistor is not shorted and that there are no obivious signs of trouble in the power supply or horizontal output area - overheated components, swollen or leaking capacitors, cracked semiconductor cases, bad solder joints, signs of high voltage flashover.

Second, measure all major output voltages from the power supply. If all of them are low but one near zero, then you have a short circuit at that line.

Third, if the supply voltages are fairly correct, check that the horizontal oscillator runs at approximately the correct frequency (check with a scope at the horizontal driver stage).