Samsung PS-42D5SD Blank Screen

[anotherdude]

Just got this originally from the description though it might of just been caps but the tv does turn on but goes from the dark black (off) to a lighter black (on)

Had a tweak at the pot on the y-main (i think) it makes the screen go fuzzy but i can see the bbc 1 ch1 in the left corner but pressing buttons on the remote brings up nothing else

not sure where to go from here

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

the LVDS board (i think) flashes/blinks green when the tv is powered on, again no idea if this is correct just something i've noticed

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

so i disconnected the lvds cable and reconnected it seems everytime i do this the picture does show briefly but then reboots the tv

read a few posts with people just having a bad lvds cable, this one does seem a little tight fitting (not much reach on the wire)

[tom66]

Re: Samsung PS-42D5SD Blank Screen

Try 3-4 jumper test...
https://www.badcaps.net/forum/showpo...61&postcount=2
Then again this isn't even a 720p TV so not sure if it supports it.

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

i've reseated the cable a few times seemed to make no difference,gave the control board a little heat with a hairdryer and several reboots later and the tv is on and working

bad control board then?

[tom66]

Re: Samsung PS-42D5SD Blank Screen

Would sound like it...

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

heard a pop and smell of burning now the colour and shadows seem off colour along with the screen being dimmer than before with a picture present, not sure whats popped

[tom66]

Re: Samsung PS-42D5SD Blank Screen

Probably the X-main or Y-main, usually these 480p TVs are not worth repairing with that fault...

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

can't see any burning signs or anything obvious on either of them

another symptomn that the hard power button on the front now no longer works either, i'm still swaying towards the control board

could a bad control board cause these problems?

there about 10-15 to replace so might aswell

[tom66]

Re: Samsung PS-42D5SD Blank Screen

I doubt a control board, which deals purely with the image on the display, could affect the power LED. Note many Samsung TVs have the power LED off when the set is switched ON.

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

i mean that the button to actually turn it on and off no longer responds the led still lights up when off and using remote

[tom66]

Re: Samsung PS-42D5SD Blank Screen

Possibly a stuck button?

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

Possibly a stuck button?

it did work before hand havent moved it or knocked it

i've ordered a contol board anyway at £12 if it doesn't fix the issues i'll scrap it

as replacing x and y mains can be costly yes?

[tom66]

Re: Samsung PS-42D5SD Blank Screen

Yes. As I said before, I would not put much money into such an old, 480p plasma.

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

replaced the control board still getting the same

screen turns on can see the colour change the image flashes on for a second then off, does this every few reboots

any suggestions?

[tom66]

Re: Samsung PS-42D5SD Blank Screen

Probably main board. Have you done 3-4 jump on new board?

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

not sure if this is the correct place, just using the old board as reference rather than take it all back out right now

only 4 pin connector i can see on the logic board, as shown 1+2 are bridged

what am i looking for removing the lvds cable and bridging 3+4?

do i still connect the main board?

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

just tried the 3-4 jumper with lvds cable disconnected and main board connected, don't get the flash off the image now more just that the screen turns on like before not sure if thats just the tv not getting lucky enough to display the flash
it still does reboot again and again too

another thing to mention, been like this since i got it but it doesn't always make the samsung turning on noise sometimes it will sometimes it doesn't, more often than not it plays it when the tv reboots a few times

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

not sure if i'm onto something here or just me guessing at a wild goose chase

just thought i'd make sure all the voltages are correct for the vscan va vg etc (correct settings are labelled at the top)

anyway they all pretty much read correct within a few volts anyway all but the VE test point which gives off no reading

attatched a picture to show this, not sure if i've got this right or not but i took off the psu board (where the test points are) and just started testing the few caps that are on the board

one of the caps gives no reading (again not much idea what i'm looking for) whereas all the other caps do give off a reading in continuity mode these being high voltage caps too, again not sure if i'm getting this right but to me would that indicate the cap is bad and it's not provding the volts to the VE? (sam young caps)

any help or guidance is much appreciated

[anotherdude]

Re: Samsung PS-42D5SD Blank Screen

little further i think

disconnected both x and y mains from the DC SMPS and the VE still does not output any voltage at the test point

so i'm either looking at a bad DC SMPS board or bad POWER Supply board correct?

is it possible for the power supply board to not output a VE voltage? as looking through various service manuals i can't see a pin out for the VE voltage on the power supply board, only on the DC SMPS board, from reading is it correct that the DC SMPS board converts the voltage, another boards £10 but the cap i think is at fault is £2+ for a panny cap