Hitachi LE55A6R9A, individual LED SPECS?

[DXseekerMO]

Hello again everyone! Today I got this Hitachi LE55A6R9A, picture on-screen with no backlights. I have confirmed there is voltage at the LED connectors on the power supply. Like many of this model this one has bad LED's.

I ordered a LED re-work station and I hope to try it out on this repair.

Has anyone here replaced individual LED's on one of these and if so, does anyone have the specs for them?

Thanks everyone!

[budm]

Did you already open up the panel to see what the LEDs look like, labeling on the LED strip, etc.?
LCD panel number?

[DXseekerMO]

Thanks for the reply budm, I haven't opened it up yet. The factory part number for the LED strip is LB55061. I'll see if I can find a picture of an original strip with the labeling and post it.

[DXseekerMO]

Here we go:

[budm]

LCD panel model number?
C550F15-E6-H?

[budm]

Originally Posted by DXseekerMO

Here we go:

http://www.shopjimmy.com/hitachi-lb5...-12-strips.htm

You will have to remove the old LED to look at the solder pad foot print and also check the Voltage of the working LED.
The LED will have to match the solder pads and polarity as well.

[DXseekerMO]

Panel number:

[DXseekerMO]

Originally Posted by budm

LCD panel model number?
C550F15-E6-H?

Originally Posted by budm

http://www.shopjimmy.com/hitachi-lb5...-12-strips.htm

You will have to remove the old LED to look at the solder pad foot print and also check the Voltage of the working LED.
The LED will have to match the solder pads and polarity as well.

Is one of those LED testers like one SJ sells good enough to measure the LED voltage, or is there a more accurate method?

Speaking of LED testers, any suggestions for a good one?

[budm]

That is good LED tester for testing the Vf at low current (30mA). It will give idea if you have open circuit in the LED string or not. It will also light up LED string that has some shorted out LEDs, in that case you will to know how many LEDs you have in the string to calculate what the Voltage reading should be based on 30mA current.
Since it does not out out real operating current, the LED may light up with tester but it will fail with real load current.
It is a good tool to have, I have one also.

[DXseekerMO]

That tester is definitely on my list. Right now I'm using batteries to check them but that really doesn't tell me anything other then the LED's work or they don't.

Does the information printed on these LED strips tell anything about what LED's are used?

[budm]

Originally Posted by DXseekerMO

That tester is definitely on my list. Right now I'm using batteries to check them but that really doesn't tell me anything other then the LED's work or they don't.

Does the information printed on these LED strips tell anything about what LED's are used?

No.

[DXseekerMO]

It looks like I'll be ordering LED strips this time, unless someone just happens to have replaced individual LED's on this model TV and still has the info on them.

I have about 50 TV's at a recycle joint to go look at Monday, maybe there will be one of these in the group. If not rumor has it there will be another truckload along shortly.

Thank you budm for helping me out again!

[vinceroger69]

The trouble is ordering the led strips is that they are from smashed screen sets etc so who knows how long they will last, i would strip the lcd down remove one led and check which pad is anode/cathode and measure the led size we can then help you find replacements

[DXseekerMO]

Originally Posted by vinceroger69

The trouble is ordering the led strips is that they are from smashed screen sets etc so who knows how long they will last, i would strip the lcd down remove one led and check which pad is anode/cathode and measure the led size we can then help you find replacements

Cool! I've got to finish this HiSense I'm working on so likely Tuesday evening I'll get pics and measurements on those LED's.

[sintv]

If you scrape the track of a working led, you cam put a meter on 'short' setting and if its a 3v led it will light up. If it doesnt light its a 6v led.

Just looked at your pictures and Id guess they were 3v

[DXseekerMO]

I was also thinking a formula like voltage output to LED's divided by the number of LED's should give me a good idea of the voltage to each LED?

[vinceroger69]

once you get a led tester it makes led repair so much easier and quicker i use mine most days now

[budm]

Originally Posted by DXseekerMO

I was also thinking a formula like voltage output to LED's divided by the number of LED's should give me a good idea of the voltage to each LED?

Voltage reading on the power supply + LED connector which is connected to the Anode of the LED string will show the Voltage of the total Vf of the LED string + Vdrops of the PWM controlled MOSFET and the current sensing resistor which is connected to the GND return.
When you using the LED tester, the tester will put out only about 30ma so the Vf will show lower than 3V. If you look at the LED Vf VS If, you will see what the Vf will be at certain current.
If the LED strip has shorted out LED then the Voltage display on the meter will show lower Voltage so you cannot really tell how many LED the LED strip has unless you know how many LED you have on the strip.
For example of what you will see when you have shorted out LEDs: Read Post #17 and later.
https://www.badcaps.net/forum/showthread.php?t=70274

[DXseekerMO]

Originally Posted by vinceroger69

once you get a led tester it makes led repair so much easier and quicker i use mine most days now

I think one will come when I place my next order. I don't like the idea of using unregulated power to test these. I tried it on a couple LED's on bad strips and 3V LED's don't seem to like 9V for some reason

Originally Posted by budm

Voltage reading on the power supply + LED connector which is connected to the Anode of the LED string will show the Voltage of the total Vf of the LED string + Vdrops of the PWM controlled MOSFET and the current sensing resistor which is connected to the GND return.
When you using the LED tester, the tester will put out only about 30ma so the Vf will show lower than 3V. If you look at the LED Vf VS If, you will see what the Vf will be at certain current.
If the LED strip has shorted out LED then the Voltage display on the meter will show lower Voltage so you cannot really tell how many LED the LED strip has unless you know how many LED you have on the strip.
For example of what you will see when you have shorted out LEDs: Read Post #17 and later.
https://www.badcaps.net/forum/showthread.php?t=70274

Ok budm I will do that.