Sony KDL-65W850A Dead

[kevinm34232]

Re: Sony KDL-65W850A Dead

I decided to go down to the LEDs.. This is different than ones I have seen before.

There are 4 strips of 65 LEDs, 2 on each side.

Each strip seems to have 5 sets of 13 LEDs, as the A and C reverse after each 13.

There are 10 wires in the harness going to each strip.

What's the best way to test these?? Testing each LED in diode mode with my DMM seems to give good readings but they don't light up..

[kevinm34232]

Re: Sony KDL-65W850A Dead

Can really use some help with testing these LEDs while I have the panel apart.. As I said, each strip has 5 "sets" of 13 LEDs. There is a common "+" for all 5 sets, but each "-" is independent of each other.

See photo with the "+" test point, and the 3 "-" test points, there are 2 more sets of 13 to the right that are not in the picture.

I am not sure how to test these, I've opened up 2 LEDs already trying to figure it out.

I tested each LED in diode mode and all seemed good, I really would like to light them up..

[dick_barton]

Re: Sony KDL-65W850A Dead

Here's a link to a video and I know that ReeceyBurger123 also has one one Youtube.

https://www.youtube.com/watch?v=eEJoPCa7Kt0

[budm]

Re: Sony KDL-65W850A Dead

'I tested each LED in diode mode and all seemed good' What does it show on the meter? 0.75. 3, 6?

[kevinm34232]

Re: Sony KDL-65W850A Dead

'i tested each led in diode mode and all seemed good' what does it show on the meter? 0.75. 3, 6?

0.75 - 0.76

Why are these reading like diodes, and not lighting up the diodes like the other strips I have?? Are these in parallel?

[dick_barton]

Re: Sony KDL-65W850A Dead

You said in an earlier post that you had a power supply so if you consider that each led has approximately 3.5V across it then to test 2 leds = 7V. Keep the current limit low say at 100mA to start with. Once you know what voltage and current is required to drive two leds brightly you can increase the voltage in proportionally to the number of leds you wish to test at a time.

[kevinm34232]

Re: Sony KDL-65W850A Dead

All other strips I have are in series, so they will light up with the DMM. These will not light up one at a time. I am confused by how they are wired, a common positive feed for all 65, but different negative for each set of 13.

I don't know where to place the leads? This is how I opened 2 of them already.

Can I hook my PS to the common +. and one of the - test points for the 13 LEDs?

Is it going be set to 3V with higher current, or 3x13V like they were in series?

[dick_barton]

Re: Sony KDL-65W850A Dead

Diah is the man to ask as he seems to have a lot of knowledge of LED's. What are the part numbers on the strips. That could help him.

[dick_barton]

Re: Sony KDL-65W850A Dead

I can't see why you can't use your power supply and quickly touch 3V across one of the leds to see the results. Not a fast test but if it works you can test all the leds.

[kevinm34232]

Re: Sony KDL-65W850A Dead

I will try it again.. So set the PS to 3V and 100 mA?

[dick_barton]

Re: Sony KDL-65W850A Dead

I feel that's a safe starting point. The led may come on but dim in which case increase the current limit slowly.

[budm]

Re: Sony KDL-65W850A Dead

0.75 - 0.76

Why are these reading like diodes, and not lighting up the diodes like the other strips I have?? Are these in parallel?

You are reading the Vf of the protection diode which is in parallel with the LED/s.
Vf of single white LED is around 3V, dual LED will be around 6V.
Reverse your probe and test them again.
BTW, your meter may not have Voltage to test dual LEDs.

[kevinm34232]

Re: Sony KDL-65W850A Dead

So I may need to test each diode at 6V?

"BTW, your meter may not have Voltage to test dual LEDs."

My meter will just barely lights a regular LED..

[budm]

Re: Sony KDL-65W850A Dead

First you need to get the correct ANODE/CATHODE pin first, so try using your meter in diode mode the establish the correct pin first, if you hook up the 3V or 6V wrong you can damage the protection diode and shorted it out.
The good LED in one way should show 0.6~0.7V (Vf of the protection Diode), and 3V (Vf of single white diode, or two LEDs in parallel), or 6V for dual LED (LEDs in series) in another way.
This is why it is important to use current limiter power supply in case you apply the Voltage with wrong polarity to the LED with built-in protection diode.

[kevinm34232]

Re: Sony KDL-65W850A Dead

With the DMM, the LEDs read 0.75V with black on the Anaode and Red on Cathode. So now what do I do?

[budm]

Re: Sony KDL-65W850A Dead

Reverse the leads and see what you get.
PDF of single LED with protection diode.

[kevinm34232]

Re: Sony KDL-65W850A Dead

Reversing leads I get 0L, that's where on the other strips it would usually light up the LED.

[budm]

Re: Sony KDL-65W850A Dead

So whe you siad when the LED lights up, what does it show on the meter then? No way the white LED will light up and show 0.7V on the meter in diode mode.

[kevinm34232]

Re: Sony KDL-65W850A Dead

They do not light up either way I place the leads on this TV's LEDs. It just reads like a standard diode.

I am saying that on the other LED strips I have worked on from other TVs, it would light up the LED (and also show 0L) with the leads one way, and show 0L the other way with no light. I would never get the usual diode reading.

I cannot get these to light up at all with the DMM, and I'm unsure how to do it safely with the bench PS.

[budm]

Re: Sony KDL-65W850A Dead

OK, it shows 0.7V, you are reading the Vf of the protection diode, that means the polarity of the LED will be opposite of what you are probing,
I.E. Red probe on one pin (called it pin 1), black probe on another pin (called it pin 2) the meter shows 0.7V. That means pin 1 is the CATHODE of the LED, PIN 2 is the ANODE of the LED.
So apply 3V 100mA in that polarity, it should light up the LED, if not it may be dual LEDs in series, then you just have to turn up the Voltage slowly. Try that on the good LED.