Repair guides and support for televisions manufactured by Sony.

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Sony KDL-75W850C 6 red blinks - where to measure LED voltage

I am troubleshooting a Sony KDL-75W850C per the service manual. 6 red blinks indicates either bad power board or LD panel. I have checked power board and I have good 3.3v STBY, 12V, and BL_ON. . It says I need to measure the LED output voltages. I assume I measure them between OUT+ and OUT- on the board. All the other points are measured to Ground. The reason I ask is I get a brief pulse of 132V between OUT+ and OUT- then it collapses to 0. If I measure between OUT+ and Ground I get varying voltages from 0 to 200V ( I assume a cap is charging discharging).

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There is an LED or two that are out on one or more of the strips. You will need to test the strips and/or the LEDs to locate the one(s) that don’t work. A single shorted LED can cause this. Please note that there are protection circuits that shut down the LED supply to prevent further damage. This is why you see the short pulse of 132V.

Dan

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Thanks for the quick reply. What is the best way to test without opening the panel which I assume is a lot of work? Can I disconnect the OUT +/- wires and validate the power supply voltages? Or disconnect the T-con board? The service manual is at a dead end - just says replace LD panel.

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There are LED strip testers out there that can be used to verify this, but its not worth it for one set. I have successfully replaced individual LEDs too. But... You need to know which one and these are surface mounted LEDs as well. There is really no easy way to get much further with this other than removing individual strips to see which one is bad. The LEDs are connected in series. Each one fires up using 3.3V (or close to it) Doing the math, you likely have 4 strips of 10 LEDs per strip. I found 2 listings for one strip each for your model on Ebay for $25 a strip. This seems a bit high, but there were only 2 listings. That is probably what the market will bear.

Talk to a local shop to see if they will either replace the strip or replace the LED if you can locate it.

Post your location. Maybe someone here is close enough to help.

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Ok thanks, I'll look at getting to the LEDs. This is for my church in northern Dallas-Fort Worth

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As a followup, I was able to remove the screen to get to the LED strips. I also bought a LED tester on eBay. Very handy device. It quickly I showed I had one LED out on a 10-LED strip. Bought a replacement strip off eBay and it works great.

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Hi Bruce,

Can you post some photos of the tools and led replacements?

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Do you still have the old strip?

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Would you sell it to me?

I am unable to locate a strip nor am I able to find out the specs for the SMD LEDs that are used so I can replace inidividual LEDs on the strip.

I feel they are 3528 type, but not sure. The XBR series has the LEDs that are used printed on the strips themselves, but I don't see anything like that on the KDL...at least from the pics I have seen. Do not want to take the TV apart until I have them. Appreciate any help!

Happy Holidays from Chicago :)

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