samsung lt22c300ew - psu pslf560501a no power

[fhss]

hello guys

i will post the others psu codes maybe it´s easy to someone help: pd23a0q / bn44-00505a

i need help to try to repair this power supply unit when the, i am not a tecnician this is just a hobby and i am trying to learn and a friend ask me for help to try to repair his tv.

so when the tv arrive didn´t power so i check the psu and ad the a few damaged componentes: fuse_fp801s, bridge rectifier_bd801s, ceramic capacitor_cm804, power ic_str w6052s.

so i did replace all the componentes and now the power supply try to power up but iu shuting down as is doing that in a loop, i ear a small click noise when that apen but i cant figure it out what it is.

can anyone try to help please?

i did test a lot of componentes and i believ they are ok, but as i said i am not an expert and is possible that i did check something wrong, i didnt found bad diodes and i did remove the eletrolitic caps to test the impedance and esr and they are good.

main cap have around 328v, in the diod dm855 i have a steady 30v more os less in and all the other voltages are going up and down.

best regards

[nomoresonys]

Re: samsung lt22c300ew - psu pslf560501a no power

Easy stuff first, check over all solder joints on powerboard, look closely, add solder to any that look suspicious, careful not to bridge any of them, examples of bad joints: https://www.google.com/search?q=bad+...ih=607&dpr=1.5

[fhss]

Re: samsung lt22c300ew - psu pslf560501a no power

Easy stuff first, check over all solder joints on powerboard, look closely, add solder to any that look suspicious, careful not to bridge any of them, examples of bad joints: https://www.google.com/search?q=bad+...ih=607&dpr=1.5

thank you for your quick reply, i did that alreay like i said i am not and expert but i did invest in good tools and i solder quite nice so that is not my problem at this point.

thank you

[nomoresonys]

Re: samsung lt22c300ew - psu pslf560501a no power

ok, that's good, now check your voltages, good video there, do it like he does: https://www.youtube.com/watch?v=XH9GfkGQX1I

[fhss]

Re: samsung lt22c300ew - psu pslf560501a no power

ok, that's good, now check your voltages, good video there, do it like he does: https://www.youtube.com/watch?v=XH9GfkGQX1I

hello
that kind of check i have done it already that´s why i know and i told that voltages are oscilating.
but do you wan´t me to post the readings i have?

thank you

[nomoresonys]

Re: samsung lt22c300ew - psu pslf560501a no power

ok, if you didnt already, for a test you can try, unhook cable from powerboard to mainboard, leave it off, plug powercord into powerboard and outlet, see if backlights come on and stay on, they probably won't if you still have powerboard issue, while your there, test your voltages on those pins again, see if they are still jumping, one very likely suspect could be the component on a heatsink close to the connector, double check your work, make sure your replaced parts are still ok, not shorted etc.

[R_J]

Re: samsung lt22c300ew - psu pslf560501a no power

Check the voltage ACROSS CM807, this is the vcc voltage for the ic (around 15~20vdc), also try replacing CM807. Check the resistance of RM803 out of circuit, then check DM803 smd diode in parallel with RM803

[nomoresonys]

Re: samsung lt22c300ew - psu pslf560501a no power

maybe check the optocoupler also.

[fhss]

Re: samsung lt22c300ew - psu pslf560501a no power

ok, if you didnt already, for a test you can try, unhook cable from powerboard to mainboard, leave it off, plug powercord into powerboard and outlet, see if backlights come on and stay on, they probably won't if you still have powerboard issue, while your there, test your voltages on those pins again, see if they are still jumping, one very likely suspect could be the component on a heatsink close to the connector, double check your work, make sure your replaced parts are still ok, not shorted etc.

hello
i have done all those steps mate, that´s why i did post to see if someone can help. i know that you mention once i said i am newbie at this but i did alreay.

thank you

[fhss]

Re: samsung lt22c300ew - psu pslf560501a no power

Check the voltage ACROSS CM807, this is the vcc voltage for the ic (around 15~20vdc), also try replacing CM807. Check the resistance of RM803 out of circuit, then check DM803 smd diode in parallel with RM803

hello

i did check cm807 before and the voltage is jumping a lot aswell, i did order these capacitor because someone told me these capacitors usually goes bad. out of the board i test it and have 47uf and 0.8 esr but i did order anyway.

the resistor rm803 i did remove before and is about 0.3ohm.

the diode rm803 i believe i bad because pin 1 and 2 are anode and pin 3 cathode and between pin 1 and 3 i have about 1.8v in both directions. and between pin 2 and 3 i have about 0.28v in one direction and other direction is o.l, i have another bad psu like this one and i did remove the diode and i test it and have between pin 1 and 3 about 0.28v only in one direction and pin 2 and 3 the same. so i did replace the diode but didn´t fix the problem have the same simptoms.

thank you

[fhss]

Re: samsung lt22c300ew - psu pslf560501a no power

maybe check the optocoupler also.

hi again

i did check before the optocoupler and betwen pin 1 and 2 i have o.l in both direction and between pin 3 and 4 the same. then i did check the optocoupler from the other psu and i have the diode junction between pin 1 and 2 but didn´t fix it.

thank you for your help

[fhss]

Re: samsung lt22c300ew - psu pslf560501a no power

one thing that i just realise now that is strange is....

the conector for tcon plugged i have no power in signal ps_on and without the connector for tcon i have about 7v but going up and down anyway.

do you guys can help me here.

best regards for both of you