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

[tieny]

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

its 102 and 123, so 1000 ohms and 12000 ohms?

Calculating Equivalent resistance I get 923 ohms.

Measure the resistors in circuit I'm getting 793 ohms

[tom66]

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

That seems OK, but the value seems a little low for a 24V rail feedback... I'm working on the idea that overloading them can change their value and cause the feedback to be incorrect.

[tieny]

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

Do you mean their resistance can drop even lower when its overloaded?

Question: whats the difference between these resistors and the other ones? how come these are green and the other smd ones are usually black?

[tom66]

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

Do you mean their resistance can drop even lower when its overloaded?

Most resistors increase in value when the fail. An increase in value leads to an increase in output voltage.

Question: whats the difference between these resistors and the other ones? how come these are green and the other smd ones are usually black?

They are precision thin film 1% or better, because the output might have a 2 or 3% tolerance which is hard to achieve with standard thin film resistors (5% per resistor, plus 2% TL431 error.)

[tieny]

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

I'm trying to find the resistors on digitizer but can't find it. Do you know where to get a replacement?

[tom66]

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

Digitizer?

[tieny]

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

oops sorry i meant "digikey" lol

[tom66]

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

Get me the values of them, using the previously linked chart, and then I can find the appropriate part or category for each.

[tieny]

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

Precision thin film resistors, "102" or 1000 ohms and "123" or 12000 ohms. thanks

[tom66]

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

Only those resistor values used?

[tieny]

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

Yeah, these two:
https://www.badcaps.net/forum/attach...6&d=1359831625

theres 3 numbers on the resistors, I just thought the 3rd number on it says how many zeros correct?

[tom66]

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

Yes, if it is just a number, that is a power of ten, otherwise, you need to use the table.
I suggest you replace all of them to eliminate any doubt.

[tieny]

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

Ok, so all five resistors?

https://www.badcaps.net/forum/attach...5&d=1359830813
https://www.badcaps.net/forum/attach...6&d=1359831625

thats 102, 123, 752, 183, 564

1000 ohms, 12000 ohms, 7500 ohms, 18000 ohms, and 560000 ohms

Just wondering, since its outputing the wrong voltages, is there any way to force and drop the voltage down by only 1 volt just to get it working?

[tom66]

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

I still don't know if I believe those values - 963 ohm parallel is very low for 24V feedback.

[tieny]

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

Theres also a 103 resistor (10000 ohms) near the two parallel 923 ohm for the 24V feedback, would it affect it in any way?

[tom66]

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

We need to draw out a schematic of this section, can you do that, or do you need help?

[tieny]

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

Hmm not sure if its right, but looking at it, it seems to be in parallel with the three main resistors.

[tom66]

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

That seems a bit more realistic; does one of the leads of the TL431 go to the middle of that divider?

[tieny]

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

Hopefully i drew this right, I might of missed a thing or two.

[tom66]

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

Makes a lot more sense - does 24V come into the feedback at all?