Samsung PN51D450A2D - Need help - Full Detail - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 5 Old 01-17-2017, 06:31 PM - Thread Starter
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Unhappy Samsung PN51D450A2D - Need help - Full Detail

Hey Guys, Im in need of some direction and assistance.
First off some background on me. I work in the electrical distribution industry, have over 15 years of mobile audio / remote starter installation experience, am firmilliar with electrical and electronics, but not so knowledgeable when it comes to circuit boards and televisions.

I have a Samsung PN51D450A2D Plasma television, a month or so ago it was on working fine, then I left the room and came back a while later to find it off and non responsive.
I pulled the back panel off, checked the fuse – was still good – but it was still un responsive. Came to the conclusion that my Power supply board was toast. Ordered a new one off ebay.
Installed the new power supply board and powered on.
The indicator led on the front of the tv lights up red and the tv plays the “Samsung tune” but no picture. No change in the screen what so ever from powered off state.
The green diagnostic light on the logic board is blinking 5seconds on 2 seconds off. Based on what ive found online this indicates Driving Board Problem (DRV Reset): LED ON for 5 seconds → LED Off for 2 seconds.
When I test the VS Testpoint on the powersupply board I only get 10 vdc. When I test the Va I only get 1vdc.
I removed and visually inspected the x and y boards and they did not look to be damaged /blackened/ or have any bulging or ruptured components.
When I removed the main board (one with the hdmi inputs) it looked like there may have been some corrosion, or oxidation on the board and the back side sticky. I took some isopropanol and attempted to clean off as much as I could. I re installed the board and attempted to turn on the tv. I didn’t get anywhere past where I was stuck.
Thinking I had a damaged board I ordered a new main board.
Installed it and still nothing.
On suggestion of the seller of the main board I replaced the logic board as well.
Still nothing new, same 5 sec on, 2 sec off diagnosis light.
At this point I tried some random trouble shooting.
I removed the xmain from the y main (xmain is fed from ymain)
No change
Removed the y main from the powersupply,
No change


I removed all the boards from the power supply and powered on.
Nothing at all.
Then I attached the mainboard to the power supply.
Nothing
I added the logic board to the powersupply and now the tv will turn on and playing the Samsung tune and 5 on 2 off blinks.
One by one I removed the various ribbon cables to the logic board. Each time I plugged in the tv I would get the Samsung tune. However, once I removed the ribbon cable from the y main to the logic board the tv went will click 5 times like its attempting to fire up. Then just turn off.
If I connect the ribbon cable to the y main and disconnect the ymain from the power supply board it goes back to playing the Samsung tune and 5 on 2 off blinks.
This lead me to believe I had a faulty y main.
Replaced this and same issue.

It seems that no matter what I do I cannot get a reading higher than 10vdc on my vs testpoint on the powersupply and 1vdc on VA.
I have metered my VSON between my powersupply and logic and have 0vdc all the time regardless of what I do.

I have done a ton of research online but cannot find anyone with a similar issue of low vs/va readings.
If there is something im missing or something I can test to help diagnose the issue please let me know and I will test and report back asap.
I would like to salvage this Television, but im getting close to the point of “office spacing” this tv in a field.
Please Help.

Thanks
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post #2 of 5 Old 01-15-2018, 11:23 AM
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sad to believe no one replied to your question.

I TOO have 5 seconds on, 2 off, and found that same tech bulletin.
I just don't know what "DRV RESET" means.

I got a free 64-inch D8000.
I'd REALLY like to use it - but spending several $100 defeats the purpose. Might as well spend $400-500 on something used on craigslist.

I measured 5v & 15v off the power board on all 3 plugs that go to other boards - no idea what the other "v?" pins are supposed to be.
BUT, my vs test pad is dead, and va pad is 5v.
BOTH sides of the 2 fuses are dead (the ones by the AC input).


One difference is that I don't get any sound.
Powers on with a relay click. Solid red light on front.
Blinking green LED.
nothing else.

Jaymer... Its only TV - Get a Life!
------------------------------------------

Last edited by jaymer; 01-15-2018 at 11:35 AM.
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post #3 of 5 Old 08-22-2018, 08:38 AM
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Hi. Did you sort out your troubles with tv?
I have similar issue.but as far I found voltage get normal if you disconnect only flexible signal ribbon from y buffer or x buffer.in my case both buffer boards.y buffer found damaged igbt transistors, soldered them out, waiting to replacement, but can not find what is wrong with X Buffer, as if disconnect x buffer signal ribbon, voltage get fine.in signal connection found that logic board not showing fault flash if disconnect only Drv_reset contact.I simulated this connection on my desk with logic and x buffer boards only and my desk power supply. To connect boards I used separated cables instead of single ribbon.if need can make video, to show that.but can not figure out what cause Drv_reset fault
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post #4 of 5 Old 08-22-2018, 02:20 PM
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To update: disconnected one by one cables that been connected instead of ribbon between x buffer and logic board, found that if keep connected 3 contacts GRD, +5V, and one Drv_reset, then no fault coming up.If add to those 3 contacts any of XE, XS or XG,then coming up fault.Mean fault caused by Drv_reset, as without Drv_reset connected, all contacts can be connected with no fault.
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post #5 of 5 Old 10-03-2019, 03:29 PM
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Same same!

I dusted my TV by using compressed air through the vent holes. Hours later, I turned it on and heard a HUGE firecracker POP! It's funny because when I dig into the TV, I do not see any problems on any boards, top or bottom.



I get weird voltages unless I unplug the Y-Main ribbon cable, then everything looks fine.


The LED blinks on for 5 seconds, off for two when everything is hooked up BUT is blinking once per second when that ribbon cable is removed.


I am going to order new Y-Main and Buffer boards. I'll post back here when I try the new boards. Fingers crossed no more pops or snaps.
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