Sony KDL-55EX640 (630) DEAD SET

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

ok pin2 of IC902 and negative of main cap is 0.00 ohms.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

no 3.3v on pin 1 of CN2

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

I will need really hi-res pictures of the bottom side of the board to trace out the STBY section.
Looking the top side of the board, it looks like IC901, T901 are for the STBY power supply section.
Please try to read the P/N as printed on the IC901 so we can check and see if the IC is getting the B+ to run it.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

I just wanted to say thanks for your help budm.

IC901 is ICE2QR0665Z data sheet attached. I'll have a look at the board and see if I can see if it's getting voltage. Maybe I could put the board into my flatbed scanned. I've been using my phone so far and it's not ideal. Maybe under my work lamp will get a better image.

This is the data sheet.

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

OK, check the resistance between the positive pin of the main filter cap and the D (Drain) pin of the IC, it should have very low resistance.
If it does, the plug the TV in and then check the DC Voltage between GND pin and the VCC pin to see if it does have 18VDC (VCC TURN-ON Threshold, see page 13 of the spec sheet) for it to start up.
Once the circuit starts up if the Voltage does not drop below 10.5V the circuit will stay on, it needs 18V to start first.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

3.3ohms from positive of main filter cap to drain pin (5) of IC901

we have a grand total of 6.2mV across pins 7 and 8 lol

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

I'm going to have to come up with a better way of getting these images. I've done the best I can by stitching them together.

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

OK, there is no open connection for B+ of the main filter cap to feed to the SMPS IC DRAIN pin.
I forget to ask you if you do have 335VDC between the two legs of the main filter cap, if you do, ten you should have the same DCV on the Drain pin.
I do need better pictures of the whole bottom side.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

I have ~344VDC at the main filter cap. One thing that is strange, I think i measured 6.6ohms between the IC901 Vcc and gnd pins. I removed the IC and got the same. When i say the same I mean with ic out and measuing the board.

I'm going to have to replace the components I've removed before I can do any more readings. I'll try to come up with better images.

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

So with IC remove and you check the VCC and GND pin of the IC, it shows 6.6 Ohms, then it is bad for sure.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

No, sorry I didn't write that very clearly. With IC removes I get ~870k on the IC legs. The spot on the board on the solder pads with the chip removed i get 6.6ohms.

Do you think this layout is similar to my board?

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

I do not know about that block diagram, I think it may have Zener Diode connected to the VCC pin to clamp down the VCC Voltage in case of spike or surge, you may look for that.
But I need the pictures to trace out the circuit of the board.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

Ok, I've tried again. It looks a bit better bit still spanned across 4 images unfortunately to try and get some detail.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

I have ~340VDC at drain pin of the IC.

I do not have anything coming out of the transformer T901 across pins 1 and 2.

I have ~340VDC on pin 3 or 4 (primary side) which runs off to Drain pin of IC901 (i grounded to main filter cap)

...and then I should have Vcc coming out on pin 1 primary side, to Vcc of IC901 (grounded to pin 2 which should be connected to B-)

Could it be possible there is a short somewhere? Or the T901 damaged? or the path back to B- ground open somewhere?

I'm an amateur, so forgive me if I have even the basics of how the transformer works mixed up

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

So you still have low 6.6 Ohms on the pad, that is where you have to find out why.

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

Lift one leg of the jumper J29 and read the resistance between VCC pad and GND pad to see if the 6.6 Ohms reading goes away.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

Lift one leg of the jumper J29 and read the resistance between VCC pad and GND pad to see if the 6.6 Ohms reading goes away.

i lifted the leg of J29 and the 6.6ohms is gone. i might try lift legs or remove IC902 to see if that makes a difference.

i removed IC902. now i've got 17volts at IC901 primary side and 3.343 standby on the secondary side

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

I see that IC 902 uses the VCC that is used by the ICE. so now you need to get the new IC902.
So what happen now when you try to turn on the TV? We may be able to fool the circuit to make it thinks that IC 902 is working.

[t4796]

Re: Sony KDL-55EX640 (630) DEAD SET

hi mate,

the tv turns on now, although initially it had a 5 blink error.

i pulled the tcon board and found some of the pins on the biggest chip were bent. i straightened them out with a razor blade as best i could. i tried powering the tv on without the tcon and it was late but i think it was still blinking but i was able to turn it on with the tv remote and the light changed to green and the backlight came on.

reconnected the tcon and it is working but with red dots. the photo makes it look much worse than it is. its not super noticeable when watching the tv.

at this point i wouldn't be surprised by anything. the guy i got it from said it worked then he went to bed, woke up and it didn't turn on.

the boards inside were all marked with the model number in marker, like you see them for sale used on ebay, held in by minimal screws, and the t-con has clearly been roughed up a bit.

[budm]

Re: Sony KDL-55EX640 (630) DEAD SET

At this point I wonder if the correct boards/board versions are installed. It is tough when someone messed with it before you.
At least now you are getting the pictures on the screen, more progress at least.