philips 39pfl2608/f7 flat tv no power high pitch sound

[Cygnus2301]

Hi everyone

I have a philips 39pfl2608/f7 flat tv which has no power and has a high pitch sound coming from the power supply (specifically from the transformer). This sound stops when I disconnect the main board from the power supply.

I measured the electrolitic caps capacitance on the board, and the resulting values show that apparently these are working ok. I removed from the board the zener diode of the primary circuit and tested it ok. Before removing the rest of the diodes from the secondary circuit to test them, I rather to ask you guys if this might be a power supply issue or not, taking into account that the noise from the transformator stops when I disconnect the main board from the power supply. This makes me wonder if this is actually a main board issue.

I also tested the outputs to the main board (AMP-13V & P-ON+21V) and these resulted the half of the value stated on the service manual, except for AL+3.3V which resulted ok.

Appreciate your help.

[dskall]

Re: philips 39pfl2608/f7 flat tv no power high pitch sound

Need good clear straight on pictures of back of tv with cover off and each board and picture of your power to mainboard connector.
Read this post: https://www.badcaps.net/forum/showth...32PFL4507%2FF7

[budm]

Re: philips 39pfl2608/f7 flat tv no power high pitch sound

"I also tested the outputs to the main board (AMP-13V & P-ON+21V) and these resulted the half of the value stated on the service manual, except for AL+3.3V which resulted ok" Those Voltages are normal when it is in standby mode.
The power supply will squeal when too much load is trying to draw lots of current.
Check the resistance between Gnd against all Voltage output pins to see if any one of then show very low resistance of < 100 Ohms. Also check resistances of ALL the diode in the cold side of the power supply if one read bad then you can remove it and test it off the board or lift one leg off the board and retest. This may be one of those set with shorted cap on the main board I just do not remember the cap designator but there are lots of threads about shorted cap on the main board.

[Cygnus2301]

Re: philips 39pfl2608/f7 flat tv no power high pitch sound

Need good clear straight on pictures of back of tv with cover off and each board and picture of your power to mainboard connector.
Read this post: https://www.badcaps.net/forum/showth...32PFL4507%2FF7

Hi dskall, these are the suggested pics from both boards.

[dskall]

Re: philips 39pfl2608/f7 flat tv no power high pitch sound

Did you read this post - https://www.badcaps.net/forum/showthr...32PFL4507%2FF7
Same problem but different boards.