Sony KDL-40W600B blank backlit screen with sound

[neilc6]

Re: Sony KDL-40W600B blank backlit screen with sound

Have same model with backlights and no picture. There was low resistance across CD3-6. Removed them all and since I was past the Digikey cutoff time, I replaced with 2 22uf caps salvaged from a scrap tcon board.

Bit tricky to get at the board since part of the bracket was blocking the shield so you need to disassemble all the boards plus a mounting bracket.

Thanks budm for the fix.

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

sorry i had to go through a move during which this got put in storage somewhere. i will one day get back to it. thanks for all the help. i havent given up yet.

[budm]

Re: Sony KDL-40W600B blank backlit screen with sound

If you still have the TV, check this out:
https://www.badcaps.net/forum/showth...246#post843246

[Davi.p]

Re: Sony KDL-40W600B blank backlit screen with sound

Another desaparecido....

[Davi.p]

Re: Sony KDL-40W600B blank backlit screen with sound

Probably the faster way to test IC and caps without removing all them is to remove only CD3, cut the track between CD3-CD4, then test again the solder pads of CD3 in diode mode, also you can test all that capacitor you've marked bad.

[Davi.p]

Re: Sony KDL-40W600B blank backlit screen with sound

12vcc is on the main white fuse FI1. Those 4 caps (2ND PIC) are probably not shorted, you have to remove them and test them with ohm meter and test their solder place the same way.

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

here is a picture of my meter. i was able to measure P1 and P2 because P2 is really easy and P1, the pin on the IC kinda sticks out a little so i was kinda sure i was on the right pin...for the other ones i just cant be sure...

you say i have to test in "diode" from P3 to 12vcc

but where is 12vcc? is that a pin on the IC?
sorry for not following well. maybe its late. maybe it will make more sense in the morning.

i did start looking for shorted caps as finntricky mentioned and did notice a few. second and third picture has them marked. they measure 0.05 on the diode setting and the meter beeps.

im pretty sure i could replace those using the hot air machine but where do i get the replacement caps? they have no marking on them

[Davi.p]

Re: Sony KDL-40W600B blank backlit screen with sound

OK i've made an "error" in the first photo, there's no need to touch the IC pin, follow where it goes and you touch there, in this case it goes on the bottom contact of LD1.

i was able to measure P1 and P2 in the first picture and i got around .5 in diode mode.

1. You said you can't touch the IC pin so how do you have measured P1?
2. P1/P2 are semiconductor's diode test, them must be measured on way and reverse with probes..
Diode mode is not continuity..

i only have one setting on my meter that beeps if theres continuity and shows what i thought was a forward voltage drop...but i hardly know what that means...

I don't know your tester, take the instruction and read... the basis... how do you think you can repair complex circuits with no knowledge of a simple tester usage?

.i dont quite understand what you mean about tracing those points to what pin of the IC they are connected to.

The continuity mode of a tester ususally is a set where a low ohm connection makes a beep so you find to where is also connected a capacitor or other component. You can use also low ohm setting but is slower because tester reading is usually slow.

and then once ive figured out those 2 pins, am i to test in diode mode between those 2 pins on the IC?

I'm sorry i've made a mistake, imagine that points P3 and P4 are internally in IC connected to a mosfet each, the Source pin, and its Drain pin is connected to Tcon's VCC (12v), so by thruth you have to test in "diode" from P3 to 12vcc (both ways) and P4 to 12vcc (idem). Internally P3 and P4 are also connected to a diode that goes to GND so you can measure P3/P4 to GND

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

thank you for the help. i will try to do this but the pins on that IC are so small, i think i need to figure out some kind of microscope or magnifying glass setup, and a thin wire attached to my probe. i was able to measure P1 and P2 in the first picture and i got around .5 in diode mode. also i thought diode mode was the same as continuity? i only have one setting on my meter that beeps if theres continuity and shows what i thought was a forward voltage drop...but i hardly know what that means...i dont quite understand what you mean about tracing those points to what pin of the IC they are connected to. do i test in diode mode and look for the pin with the lowest voltage drop related to the test point, or do i use resistance mode and chose the pin with the lowest ohms related to the test point? and then once ive figured out those 2 pins, am i to test in diode mode between those 2 pins on the IC? or... well idk what you mean about "double points" ...
sorry

[Davi.p]

Re: Sony KDL-40W600B blank backlit screen with sound

First the component with K is inductance and has only 2 terminals (maybe seems 4 but are connec. 2 at 2). I have marked on first picture in blue the jumper you can do, then points P1,P2 you must measure in diode mode between 2 arrows, points P3,P4 you must check in continuity to which pins of the chip them are connected to and then test those 2 double points with diode mode, if those tests shows approx a 0Volt (all this tests without current) then the mosfets/diodes inside the chips are bad.
In the second picture i've marked P1,P2 to test in diode mode, same as above, P3,P4 i.e. Q1/DK1 are a mosfet and a diode you must test in diode mode if them are bad.

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

ok here are the voltages in that area
im interested in this jumper idea you speak of but i need clearer instructions what to jump...
in the second picture i drew a line indicating what i think you're saying.
is that the jumper i should make?
i dont know what that component is with the K on it...is that a condenser, as you called it? what does that do?
it has 4 solder pads..which one would i solder to?

[Davi.p]

Re: Sony KDL-40W600B blank backlit screen with sound

Apart the jumper wire test with some imagination one can test the power mosfets and diode that here is almost inside the ICs but first i need the picture of the other part i have linked before, then if readings are zero volt you can post the simple picture focused.

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

davi.p thanks for the reply. somehow i always get one of the letters wrong when reading these IC markings need to look again, and think outside the box on what a letter COULD be. i do have a hot air station and i could replace these IC's if necessary but what test can i do to be sure?

finntricky thank you also for your input. were you able to fix these 2 tvs? your story comes to an abrupt end. the ones that were shorted, did you replace them? what happened? thanks!

i try to stay on my thread until the end, and if i give up an throw away the tv, at least i make a post to let everyone know

[finntricky]

Re: Sony KDL-40W600B blank backlit screen with sound

i have just done 2 tv's with the same problem, all i did was to check for shorts on all the surface mount caps, marked any that was shorted and removed them to test again, you will find that if one has sorted, the rest in that circuit will show short as well,

[Davi.p]

Re: Sony KDL-40W600B blank backlit screen with sound

Ok i was probably wrong for the post count, i have also 4000 posts in italian subforum, anyway i was hoping that you knew some basics, if not the threads usually goes dead with no solution, usually i try to do my best to give testing guides but i receive dead threads with no useful story. It needs a lot of luck where being in a not well documented area. If you say there are 0 volts everywere then one of the 2 much probably things is that one of the 2 multifunction p.supply chips are bad, are you able to do a replacement in that uncomfortable situation? The second is that the screen driver chips are toasted and carries to a protection of the remaining circuits. Very hard to find which. For the last, the ps chips are from Richtek, the common brand for today's Samsung screens, but they usually don't provide the fu**ing datasheets and this is the case (checked on its website)... it is RT6917GQW not PT6917GQW.. so U have to be so lucky to solve this puzzle.. I have seen also programmed chips in theese Samsung so prob. you can't change them and hope.. It's possible also chips are ok but memory inside is cleared...

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

your logic related to post counts has a flaw. if i knew what i was doing, i wouldn't have had to make so many posts. clearly i need help to understand what exactly is going on in these circuits, and most of those posts are asking a lot of basic questions related to that. i have learned a lot, and fixed a lot of tvs with the basic troubleshooting methods that lead to which board is bad, or repairing backlights. those are straightforward processes. understanding the circuitry and components on the boards and identifying which component to replace and why, without just guessing and removing,testing, replacing everything in sight until you luck upon it... still seems like magic to me. i might be able to follow what you said in your post, and solder that wire correctly to the places you said, but i dont quite understand why im doing that...

i will get back with those voltages, but as i recall, they were all very low if not zero voltages

[Davi.p]

Re: Sony KDL-40W600B blank backlit screen with sound

triplefour i have first read your posts count that is more than mine, i thought you were familiar with electronics...

you better to check voltages also in this picture, only capacitors:
https://www.badcaps.net/forum/attach...5&d=1526164190

ICD1 is not working, to make sure it is bad or is another, you can try to solder a jumper wire from cathode of DI3 (near the fuse, upper pad) to one of those 2 condensers connected to LD1 in your last picture, on the pads that measure ,39v. In this way you can maybe ensure that the internal switch for the Avdd in ICD1 is working or not, maybe from this depends all subsequent voltages that are missing. I don't know which voltage sequence has this board, not all are the same, it's possible that the voltages generated in the part of the link above is not working and do not switch on ICD1. Bye...

[nomoresonys]

Re: Sony KDL-40W600B blank backlit screen with sound

What if anything is the led indicator on the front of tv doing, with everything connected, any blinking or anything, in standby and or when you hit power button?

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

ok to respond to andrew

and i added a couple more voltages to the picture (they are bigger font)

1. Vin: 12V (we confirmed as present)
2. Vdd (Vlogic, Vddd): 3.3V - I cant find this, but i find VCC 3.3v which sits at 0.81
3. Vda (Vs, Vsource, Vdda Avdd): 14V to 20V - i have AVDD which reads 0.02v
4. Vgh (Vgon, Von, Vddg): 20V to 30V - i dont see this marking anywhere
5. Vgl (Vgoff, Voff, Veeg): -5V to -7V - i dont see this marking anywhere

now to find that datasheet for ICD1
which has markings
PT6917
GQW
FMP16

i found this but it says its for a LED Driver...which im pretty sure isnt what im looking for?

[triplefour]

Re: Sony KDL-40W600B blank backlit screen with sound

tv repair is a hard language to learn. sometimes what seems simple to you by now because youve done it so many times, is actually not easy to understand for the noobs if you dont put it in simple terms. use more words not less. noobs need more words, and careful, precise, unambiguous words! or we will keep going in loops.

that said, i think i understood some of the words, and will try to check and report back more voltages in the next few minutes