Samsung ln46d550

[heavymachines]

Ok this tv is getting no backlights but does have an image seen with a flashlight.
However when i check the primary caps on power board it is only reaching about 190 volts not getting the boosted voltage needed for backlights.

[heavymachines]

Re: Samsung ln46d550

pics provided by shop jimmy

[dskall]

Re: Samsung ln46d550

So in stand by you have around 162vdc. So you have some boost. Check your resistors around pfc controller. What is number on controller chip?

[attainteddragon]

Re: Samsung ln46d550

is 190v in reference to cp 802 and cp803?

i don't see you getting your secondaries active with that.

is ps/on staying high?

[heavymachines]

Re: Samsung ln46d550

is 190v in reference to cp 802 and cp803?

i don't see you getting your secondaries active with that.

is ps/on staying high?

Well actually it's gotten worse. on or off now cp802 and 803 is only getting 171 volts. ps-on is getting .005 volts off and 3.48volts on.

[Andrew F. Ali]

Re: Samsung ln46d550

Ok this tv is getting no backlights but does have an image seen with a flashlight.
However when i check the primary caps on power board it is only reaching about 190 volts not getting the boosted voltage needed for backlights.

You don't seem to have a PSU problem. I am almost certain you have a failed backlights problem

[heavymachines]

Re: Samsung ln46d550

You don't seem to have a PSU problem. I am almost certain you have a failed backlights problem

primary caps on ps is not boosting. only reaching 170 volts on or off now . could it not be boosting due to backlight failure?

[heavymachines]

Re: Samsung ln46d550

So in stand by you have around 162vdc. So you have some boost. Check your resistors around pfc controller. What is number on controller chip?

Controller ici801 is bd9275f

[budm]

Re: Samsung ln46d550

IC in the PFC section will be ICP???? (Designator for the parts in PFC will have 'P' as part of the designator), so the PFC IC is ICP801.
Check DP810 for shorts or bad leakage resistance.

[heavymachines]

Re: Samsung ln46d550

IC in the PFC section will be ICP???? (Designator for the parts in PFC will have 'P' as part of the designator), so the PFC IC is ICP801.
Check DP810 for shorts or bad leakage resistance.

Ok learning. DP810 with one leg lifted reads 0 one way and .502 the other in circuit its dead short both ways. .000 in diode mode on fluke 75 multimeter.


Have much to learn about leakage and how to detect it.

[budm]

Re: Samsung ln46d550

"Ok learning. DP810 with one leg lifted reads 0 one way and .502 the other in circuit its dead short both ways. .000 in diode mode on fluke 75 multimeter"
I do not understand 'the other in circuit its dead short both ways'. What is 'the other' that shows dead short?
IF it shows dead short when measured in the circuit then the snubber cap is probably shorted out, that cap is connected in parallel with that PFC diode.

[heavymachines]

Re: Samsung ln46d550

"Ok learning. DP810 with one leg lifted reads 0 one way and .502 the other in circuit its dead short both ways. .000 in diode mode on fluke 75 multimeter"
I do not understand 'the other in circuit its dead short both ways'. What is 'the other' that shows dead short?
IF it shows dead short when measured in the circuit then the snubber cap is probably shorted out, that cap is connected in parallel with that PFC diode.

let me get more specific.


With diode dp810 in circuit it reads .000 both ways.

now with 1 leg lifted it reads 0 one way and .502 the other way

Snubber cap have no idea where i see cp804 and few other possibility. not an expert like u. i will check caps inline with that diode.

[heavymachines]

Re: Samsung ln46d550

Hey that was it, checked cap CP820 and measured it in tester and it was junk measured like a resistor rather than cap. on DMM it measured short.


markings on it was 221 1k


replaced it with 221 2k and problem solved tv works now as it should. thanks budm .....

[budm]

Re: Samsung ln46d550

Thanks for the follow-up, that snubber cap is connected in parallel with that diode, those caps are common failures.

[heavymachines]

Re: Samsung ln46d550

Thanks for tip.