higher standby voltage on a phillips tv power supply

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

the transforner is T501

[budm]

Re: higher standby voltage on a phillips tv power supply

Ok now theres picture on the screen. But the backlight transformer started buzzing lightly when picture is there. Below are the readings from left.

Silver - 5.50v
Black - 69.6v
Silver - 69.6v
White - 133.7v
Silver - 5.66v
Blue - 69.7v
Silver - 69.7v
Red - 134v

Please put the pin name on each pin of that LED connector, your picture is not showing the pin names.

[budm]

Re: higher standby voltage on a phillips tv power supply

Not really sure. The tv came like that. There's no heat though. Now the tv had good picture and sound. Except the buzzing sound from the back light transformer.

Some one worked on that wire.

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

Please put the pin name on each pin of that LED connector, your picture is not showing the pin names.

LED 4K - Silver - 5.50v
LED 4A - Black - 69.6v
LED LED3K - Silver - 69.6v
LED 3A - White - 133.7v
LED 2K - Silver - 5.66v
LED 2A - Blue - 69.7v
LED 1K - Silver - 69.7v
LED 1A - Red - 134v

[budm]

Re: higher standby voltage on a phillips tv power supply

the transforner is T501

T501 is the power transfomer that supplies 12V, 24V, and VLED power supply that feed the two LED boost converter power supplies to drive the LED strings.
So disconnect the LED connector and see if the buzzing stops.

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

T501 is the power transfomer that supplies 12V, 24V, and VLED power supply that feed the two LED boost converter power supplies to drive the LED strings.
So disconnect the LED connector and see if the buzzing stops.

when the tv is only on no signal mode, buzzing is lower, but if i put a picture or movie on, it becomes louder. I disconnected the backlight cable, no buzzing sound. I can see still image on the screen if i put a torchlight.

[budm]

Re: higher standby voltage on a phillips tv power supply

when the tv is only on no signal mode, buzzing is lower, but if i put a picture or movie on, it becomes louder. I disconnected the backlight cable, no buzzing sound.

Put the LED connector back in place, then lower the Backlights level (not brightness) to about 30% to see if the buzz gets lower.

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

Put the LED connector back in place, then lower the Backlights level (not brightness) to about 30% to see if the buzz gets lower.

Ok the thing is, this tv doesnt have a backlight adjustment, it only has 3 modes, standard, power, best picture. So i assumed best picture is high and i selected it, buzzing a bit louder, then i put standard or power mode, buzzing goes lower. Then i started playing with contrast, when goes to 30% it buzz louder, goes to 50% not loud, below 30% louder. When playing a video, buzzing is lower. I think the buzzing gets louder when image becomes more brighter

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

So what u think? The driver circuit? Already tested all the caps around. All of them are ok.

[budm]

Re: higher standby voltage on a phillips tv power supply

Ok the thing is, this tv doesnt have a backlight adjustment, it only has 3 modes, standard, power, best picture. So i assumed best picture is high and i selected it, buzzing a bit louder, then i put standard or power mode, buzzing goes lower. Then i started playing with contrast, when goes to 30% it buzz louder, goes to 50% not loud, below 30% louder. When playing a video, buzzing is lower. I think the buzzing gets louder when image becomes more brighter

Contrast is for Video adjustment, it does not affect backlights level or backlight circuit.
Are you sure the buzz is not coming from speakers?

Try adjusting brightness, this TV may be using brightness for the backlights level adjustment.
Also try turning off 'DYNAMIC BACKLIGTS' mode, see page 36 of user manual: https://cdn.badcaps-static.com/pdfs/...45d25a9b6a.pdf

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

Contrast is for Video adjustment, it does not affect backlights level or backlight circuit.
Are you sure the buzz is not coming from speakers?

Try adjusting brightness, this TV may be using brightness for the backlights level adjustment.
Also try turning off 'DYNAMIC BACKLIGTS' mode, see page 36 of user manual: https://cdn.badcaps-static.com/pdfs/...45d25a9b6a.pdf

Speaker is down to zero. Dynamic contrast is off. Dynamic backlight is off. Now the buzzing sound gone way lower.

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

but if play videos with bright movements. Buzzing get louder. Depends on the brightness and contrast.

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

Tested everything else including caps. This is the only thing buzzing. The rest all seems fine. The transformer gets pretty hot though.

[dick_barton]

Re: higher standby voltage on a phillips tv power supply

Is that a crack on the transformer. Others have had ferrite transformers that have cracked possibly from overheating of the windings. There is a post on the forum regarding this issue.

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

Is that a crack on the transformer. Others have had ferrite transformers that have cracked possibly from overheating of the windings. There is a post on the forum regarding this issue.

Haha no. Thats just a scratch. Seems like an aluminum plate to take heat.

[budm]

Re: higher standby voltage on a phillips tv power supply

1) If you push the transformer body with wooden stick, does it change the pitch?

2) Monitor the PFC Boost Voltage on the main filer cap to see if it is around 380 ~ 400VDC and see if it goes up and down with the buzz level, do the same on the 24V output. see if it goes up and down too.

3) Check the DCV on the connector CN 4 Pin 10 BL-DIM1 when you change the brightness or contrast setting to see which one affect the BL-dim control signal, you need to use static Video source to do this test, also turn off Dynamic backlight.

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

1) If you push the transformer body with wooden stick, does it change the pitch?

2) Monitor the PFC Boost Voltage on the main filer cap to see if it is around 380 ~ 400VDC and see if it goes up and down with the buzz level, do the same on the 24V output. see if it goes up and down too.

3) Check the DCV on the connector CN 4 Pin 10 BL-DIM1 when you change the brightness or contrast setting to see which one affect the BL-dim control signal, you need to use static Video source to do this test, also turn off Dynamic backlight.

Ah finally. Its this fella thats making the noise, not the big one. When i press this guy with a stick, sound stops. And also what suppose to be 24v is showing 25.3v. Is that normal?

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

Should i dip the small fella in varnish and dry it?

[budm]

Re: higher standby voltage on a phillips tv power supply

That is one of the two Boost converter inductor that boost the Voltage to drive one of the two LED strings, this one drives that set of four wires counting from the left of the LED connector, the 4th wire has long exposed wire that I mention before.. Some one trying to fix that section may be that is why the wire is exposed like that, no way the insulation of the wire can be that much removed by itself.
Jut swap that inductor with another inductor to see if the noise will move to the new location or not first.
BTW, you should put insulation tape on that exposed wire before it is shorted to the chassis and causes damages.

Also look real close to see if that exposed wire is still properly crimped to the terminal.

"what suppose to be 24v is showing 25.3v. Is that normal?" That is fine, it is not tightly regulated power supply.

[DjKrish]

Re: higher standby voltage on a phillips tv power supply

That is one of the two Boost converter inductor that boost the Voltage to drive one of the two LED strings, this one drives that set of four wires counting from the left of the LED connector, the 4th wire has long exposed wire that I mention before.. Some one trying to fix that section may be that is why the wire is exposed like that, no way the insulation of the wire can be that much removed by itself.
Jut swap that inductor with another inductor to see if the noise will move to the new location or not first.
BTW, you should put insulation tape on that exposed wire before it is shorted to the chassis and causes damages.

Also look real close to see if that exposed wire is still properly crimped to the terminal.

"what suppose to be 24v is showing 25.3v. Is that normal?" That is fine, it is not tightly regulated power supply.

Ok, swapped the inductor. Now the sound is back to this side So its confirm the inductor varnish id dried up. As for the main caps, on both are 386V. Already insulated the exposed wire. Yes the exposed wire is properly crimped to the terminal, add more, i just resoldered it. to make sure its not loose.