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Old 09-22-2020, 09:19 PM   #1
mikey5791
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Smile Help on Samsung Syncmaster 732N LED conversion

Samsung Syncmaster 732N LED conversion project

Hi,

Yesterday i received this lcd monitor free but the owner says the backlight doesn't work anymore. I removed the metal case and tested the main and power board on an acer lcd monitor and the lcd display comes out fine, meaning the power board and inverter still in working condition. Now my plan is to replace the old non working ccfl tubes(upper 2 tubes and bottom monitor 2 tubes) to led bulb. I saw some online china seller selling led conversion kit but i couldn't get any info on the led by asking those seller. I wonder if those led are bright enough to light my monitor screen. Here is the link
https://shopee.com.my/355mm-LED-Back...869.6210934918

Btw, the led driver board has four pin out with color of red, yellow, yellow and black. Has anyone done these type of led conversion and kind enough to point out on which part of the power board i need to connect all the four pin out.
My guess is the red pin out is for positive 12vdc, black pin out is the ground negative.
Hope someone can share or suggest their knowledge to help me complete this project. Thanking in advance.
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File Type: jpg IMG_20200923_092212.jpg (1.68 MB, 11 views)
File Type: jpg IMG_20200923_090351.jpg (1.69 MB, 10 views)
File Type: jpg IMG_20200923_090024.jpg (1.02 MB, 9 views)
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Old 09-26-2020, 01:10 AM   #2
mikey5791
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Default Re: Help on Samsung Syncmaster 732N LED conversion

Found this wiring diagram at this link https://elektrotanya.com/samsung_732...wnload.html#dl
of 9 pin assignment at page 74 but not sure where the two yellow wires from led driver board (yet to buy) connect to my samsung power board (integrated with inverter).

If i connect those two yellows wrongly, the led driver board might go busted.
I hope that someone who are experienced and knowledgable can kindly point to me where to solder those yellows correctly. I just don't want to throw this old monitor to the dump due to few burned ccfl lamps. Thanking in advance.
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Old 09-26-2020, 09:50 AM   #3
R_J
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Default Re: Help on Samsung Syncmaster 732N LED conversion

You need the information for the led board, the yellow wires are likely led on/off and led dim. The Samsung seems to have 2 dim lines, A-dim & B-dim, connecting either dim line to the led board should be safe, but I would use the B-dim. You should also lift the VCC line for the ccfl driver circuit, It looks like lifting J301 will do that.

Last edited by R_J; 09-26-2020 at 10:13 AM..
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Old 09-26-2020, 10:23 PM   #4
mikey5791
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Smile Re: Help on Samsung Syncmaster 732N LED conversion

RJ,

Just now i did some live voltage check on the power board and got the following:

Pin 1( B dim)=0v (as you suggested to solder to second yellow wire on led driver board)
Pin 2=16.8v (will use this to solder to red wire VIN on led driver board)
Pin 3 to 5 are ground.
Pin 6,7=5.3v
Pin 8(A dim)=0v
Pin 9(on/off)=2.8v (will use to solder to first yellow wire ENA on led driver board)

Are the above wiring setup ok?
The black wire on led driver board will be soldered to any ground screw. Btw, i will place order for the said led driver board by next week after gathering useful wiring info.
I will also lift off J301, and to be sure maybe i will dismantle those tiny blue caps at c301,c302,c303,c304 just before those ccfl lamp connector.
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Old 09-27-2020, 10:22 AM   #5
R_J
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Default Re: Help on Samsung Syncmaster 732N LED conversion

If you lift J301, that will disable the inverter section so you can leave the blue caps in place.
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Old 09-28-2020, 08:47 PM   #6
mikey5791
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Default Re: Help on Samsung Syncmaster 732N LED conversion

Fyi, I had placed order on the led conversion kit.
Due to the current pandemic situation, the kit will probably arrive at my door step in 1-2 months time. Once the kit is installed, I will post an update here.
Many thanks for the kind assistance.
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Old 10-07-2020, 07:26 PM   #7
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Smile Re: Help on Samsung Syncmaster 732N LED conversion

RJ,

The led conversion kit arrived yesterday and i fit in all the wiring, lift J301 then tested the monitor.
Voila ! It works and the brightness is adjustable. To be honest, I am quite satisfied with the led quality and hope it will continue to work for many years to come.
Thank you for the generous advice and kind assistance without which I may not be able to do.
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Old 10-07-2020, 08:59 PM   #8
R_J
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Default Re: Help on Samsung Syncmaster 732N LED conversion

Thanks for the follow up on the conversion, I hope the led's in the monitor last, in TV's ccfl's backlights seem to last longer than led's
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Old 10-11-2020, 11:34 PM   #9
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Default Re: Help on Samsung Syncmaster 732N LED conversion

Nice work!
I bet the power supply / monitor also runs a lot cooler now.
The only slightly concerning thing I can see here is one of the yellow wires running over the high-voltage / primary side on the PSU board, as seen in this picture:
https://www.badcaps.net/forum/attach...4&d=1602120345
Generally, you want to keep secondary-side wires and circuitry away from the primary side by some minimum distance. This is for user safety, in the even of a component failure on the primary side possibly burning out and burning through the wire, causing it to become live. Since the monitor is grounded, of course, nothing bad is likely to happen. But from a design standpoint, secondary side circuitry should be kept away from the primary side.

Anyways, sorry for the rambling. Hope the monitor works well and long time for you. Please keep us posted if you can, if something does happen to this mod. It would be great to know how long those LEDs last. From what I've been told so far, those replacement backlights are actually pretty good and usually last much longer than LED backlights in TVs.
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Old 10-14-2020, 12:46 AM   #10
mikey5791
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Smile Re: Help on Samsung Syncmaster 732N LED conversion

momaka,

You have a very detail eye spotting the yellow wire running over the primary side.
To be honest i didn't think about this issue back then plus maybe the length of the wire is limited and the placement of the led driver.
I will sure keep your points and remember this if i have the chance to do another similar mod. Hope it lasts for many more years.
Indeed the monitor runs cooler now and the picture is not so bad too. If the monitor starts acting weird or runs into trouble, i will post again in this forum. (Will keep my fingers crossed though)
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Old 10-14-2020, 01:58 AM   #11
stj
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Default Re: Help on Samsung Syncmaster 732N LED conversion

i fitted those in LG in the past .

what i like to do is remove the old ccfl transformer and fit the led board in it's place with double-sided foam tape.
it keeps everything neat and tidy.
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