40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Good pics, thanks. Can you read the part # on the tiny IC4901?

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

I can't seem to find IC4901, did you mean IC6401 (If I'm guessing you tried to read it backwards? lol)

I can't see it myself but luckily I finallly fixed my original camera and i think it can pick it up. I think it says EB1?

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Got a perfect photo of the label! =D

What does that triangle symbol mean?

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Yeah that's the one. No schematics in the manual. Can't find anything for that device. But it definitely looks like a TL431...

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

What exactly does it do?

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Voltage reference - regulates the outputs.

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

So I have to replace it with a TL431?

I've been looking around for an EB1 datasheet. Does this look like the one?

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Give it has three pins connected, but that device has only two, it seems unlikely.

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

The right pin measures 2.49V steady as it cycles through the problem.

The left pin measures 10.84V steady only when the lights come on, when it goes off it goes unsteady between 10.20V to 10.77 V

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

2.49V is good actually -- that's the reference voltage. On this picture https://www.badcaps.net/forum/attach...1&d=1359769688, is there 12.9V at the jumper near R6411?

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Do you mean here? Getting 12.9V on th right and 2.5V on the left

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

The two resistors below it, in this case.

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

heres what i got on those two resistors

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

It appears to combine feedback from 24V and 12V, unlike singly regulating just one rail. So the fault is most likely in the lower feedback resistor, which these two connect to. Are the values for any of these written on the devices? They will be written in code e.g. 10C.

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Heres the label of the resistors.

Is 752 the lower feedback resistor?

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Those are the main ones, but see that common trace they all feed into? This should go into the "TL431", then there will be a resistor from there into ground, do you see that?

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

ah, do you mean these?

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Is one of the ends there grounded, and the other end goes to those three resistors? Test for continuity.

[tieny]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Yep I thats right, one is grounded and the other goes to those resistors

[tom66]

Re: 40" Sony LCD KDL-40EX500 Seconds to black (6 blinks)

Good.

Read the values off each.

Then use this SMD code table to work out the values:
http://www.talkingelectronics.com/pr...-Markings.html

For the two parallel 24V resistors, read their individual values, then calculate the equivalent parallel resistance using Rpar = (R1*R2)/(R1+R2).