Re: Samsung PN51D7000FF cycling off and on

Glad to hear Nick and bp805 were able to fix their TVs.

@ZnsaneRyder - It is possible the board from the lower model of the TV might work, but you may lose some features. I replaced the board in my 7000 with an 8000 board and gained use of wi-fi without having to plug in the dongle I previously needed to enable it. You would likely go in the other direction and need to add in the dongle if you rely on the TV's wi-fi. I am not sure what other capabilities might be different.

Re: Samsung PN51D7000FF cycling off and on

Hi sorry for the late response. Things have been busy. What I had told bp805 via PM was my diagnosis was confirmed by a local shop. They were able to power up the panel without the mainboard connected. In that state the TV no longer power cycled. Unfortunately I am not sure how they accomplished this. The LVDS cable in my TV is still in good shape, so I can't comment on the possible impacts of that for this TV. I ended up getting my board on ebay because, like Nick said, Samsung does not sell them anymore. Get it from a seller who allows...

Re: Samsung PN51D7000FF cycling off and on

One last post in case this helps anyone else. I was able to fix my TV using the main board from a PN51D8000FF/FFXZA. The board was not documented as compatible with my TV so YMMV. I compared all the other boards in my TV, and they were listed as compatible replacements for the D8000. I took a gamble and ordered a model BN94-04402C board, which as it turns out does work in my TV.

Re: Samsung PN51D7000FF cycling off and on

I wanted to post that I found a resolution for my problem. I was able to confirm by working with a local repair shop that the main board was bad. Unfortunately I am unable to find a replacement, but maybe someone else can benefit from this information.

PS - If anyone happens to know where I could get a main board I would appreciate the info. I cant afford an OLED TV atm, and my TV is setup in a room with no windows/natural light so i need something with those deep blacks.

Re: Samsung PN51D7000FF cycling off and on

Thanks very much for the suggestion. I unmounted the PSU board and carefully looked over all of the joints. I was unable to find any cracks. In particular the larger joints connecting whatever those are under the heatsinks looked solid. Anything else that I might be able to check?

- Jason

Re: Samsung PN51D7000FF cycling off and on

After more discussions with some electronics guys around the office they asked me to check if the 5VSB flicks off when the TV cycles. They suggested that behavior might point to the power board. When I tested the standby voltage does not vary even .01v during a cycle (at least not in a time frame my meter is able to display). Any chance that means the main board may be causing the power cycle?

Thanks.

Re: Samsung PN51D7000FF cycling off and on

So i got the meter from work today and measured what I gather are the key voltages based on my research here and in the quick service manual. Voltage info sticker and board images are now attached.

Va = 58.3
Vs = 207.9
Ve = 79.7
VSC = -186.2

Incase any of these might be useful:

STBY 5V=5.25 while the tv is off
PS_ON= 0.165 while the tv is on, 3.325 while the tv is off
VS_ON = 3.262 while the TV is on, 0 while the TV is off

Once again any assistance...

I have a Samsung PN51D7000FF that over the weekend started cycling off then back on again. It generally runs for 2-3 minutes then powers off and back on. This continues no matter how long the TV is left on. Turnaround time on the cycle (on -> off -> on with picture and sound again) seems to be 5-6 seconds. None of the caps are swollen or visibly leaking. The only fuse I see is on the power board, and I assume it is OK because the TV powers on still. I verified that disconnecting the board with the power button does not improve the situation. Picture and sound quality are still good and seem...

Re: New Members - please post your introductions here

Hi Everyone. My Name is Jason. I am from the Philadelphia suburbs. I have worked in IT for 15 years or so assembling servers, personal computers, working with VMs... I am mostly a Windows guy but I dabble with Unix/Linux sometimes. I have very little ability when it comes to board level troubleshooting and repair (and just enough guts to fix a few appliances in the past on my own), which is why I am here.