Samsung plasma PN42C450 shut down

[Cailloux]

I have a Samsung plasma TV PN42C450B1D year 2010 with a strange problem. An outstanding picture. Cold start, after 20 minutes, the picture disappears, the sound is still present, it responds with the remote control (power on / off, volume, input changes).
I turn off tv then i turn on tv, the picture appears then disappears after 10 minutes. Vs and Va shut down, this is normal since Vs_on from control board goes low, but why?
I do not have the service manual.

With a picture, I checked every voltage, Vs, Va, Vscan, +5, +15, PS_on, Vs_on (3.3v), all normal.
I know, you think it's a heat problem.
With my blower, I heated each card individually, it does not cause immediate concern, may take several tens of minutes before shut down.
I know, you think it's a mechanical problem.
I inspected the power supply, the Y main board, Z board and the Control board. Solders and capacitors look good.
With power on, I hit every board, nothing happens.

The most incredible, one night she has been in operation for over three hours, sometimes an hour, it is incomprehensible.
I can not target the problem. But i can tell you, the heatsink of the Y main come very hot.
I forgot to mention, I installed two fans on the back panel for ventilation. This does not change the problem.
Thanks

[tom66]

Re: Samsung plasma PN42C450 shut down

Tap on that large central heatsink with transistors mounted to it. If I'm right, it has cold solder joints. VERY common for this particular TV and the 50" version.

[Cailloux]

Re: Samsung plasma PN42C450 shut down

I removed the Y main, and re-inspected with a high magnifying glass.
Nothing found. Replaced the board, turn on TV, 45 minutes later the picture has disappeared.

[psmedley]

Re: Samsung plasma PN42C450 shut down

The board tom66 is referring to is the power supply board in the top rh corner of your second picture

[Cailloux]

Re: Samsung plasma PN42C450 shut down

Ah! sorry. I removed the power supply, and re-inspected with a magnifying glass. No cold solder found. Resolder the power transistors to be sure. 50 minutes later the picture has disappeared again.

[electronicsurplus]

Re: Samsung plasma PN42C450 shut down

The reason your Y-Sus is getting very hot is most likely due to shorted IPM Module on the Ysus.or, partially shorted IC's on the buffer. you can be sure by removing the buffer from the Ysus and check the heat and, also by checking the exact voltage (VA and VS) voltages when the buffer is connected and disconnected and, see if there is any voltage drop.

I will see if I have a service manual for this set and, if so I will send to Tom66 and he can upload to his/our service manual site for you

If the problem is in the Buffer the buffer is available @ shopjimmy.com for approx $30. If the problem is in the YSUS, you can repair it for approx $40. or so by replacing the IPM module and some caps or, replace the board for about the same price. I have experience dealing with this set and will offer some help to you as well as the excellent and willingly helpful techs here.

Jon

Electronic Surplus

[tom66]

Re: Samsung plasma PN42C450 shut down

These Samsung Y-sustains only use discrete MOSFETs. They die quite a lot. They run VERY hot because they are cheaply designed. However, I'd be more inclined to suggest a temperature sensitive component on the main board.

[randtek]

Re: Samsung plasma PN42C450 shut down

If you look at post #11 of this thread:
https://www.badcaps.net/forum/showthread.php?t=19522&
I give a procedure for testing that may help you narrow down your problem, or at least eliminate the main board as your problem.

[Cailloux]

Re: Samsung plasma PN42C450 shut down

Thank you to Randteck, I tried the trick, it's a good test tool. I followed his procedure to eliminate the main board. After 1h35m the tv shutdown.
Now who is the ugly board. I think but am not sure, the Y main would it be responsible?, it gets very hot.

[PowerAmpFreak]

Re: Samsung plasma PN42C450 shut down

These Samsung Y-sustains only use discrete MOSFETs. They die quite a lot. They run VERY hot because they are cheaply designed. However, I'd be more inclined to suggest a temperature sensitive component on the main board.

Could you please specify in detail what makes you believe those discrete Y-SUS boards are cheaply designed,
I prefer discrete Y-SUS boards hundred times more than garbage hybrids...

[tom66]

Re: Samsung plasma PN42C450 shut down

Could you please specify in detail what makes you believe those discrete Y-SUS boards are cheaply designed,
I prefer discrete Y-SUS boards hundred times more than garbage hybrids...

I like the discrete boards over hybrids. Then again it makes little difference as the FETs/IGBTs are custom and a nightmare to source. But the components are poorly sized for the power dissipation. I have also similar complaints over the Z-sustain/X-main. Seen too many of these boards die...

[Cailloux]

Re: Samsung plasma PN42C450 shut down

Hello, I have finally solved the problem, I did not replace any boards.
At first, I mentioned having installed two fans in the upper back panel, one left the other right.
It draws air from the inside to the outside to expel the heat.
I installed a third fan in the bottom left, near the Y-Sustain, it draws air from outside.
That's it, it works very well for over ten days, every night without problems. Three fans, 12 volt @ 150mA each.
Thank you for your support.

[Tim_1971]

Re: Samsung plasma PN42C450 shut down

Hello, I have finally solved the problem, I did not replace any boards.
At first, I mentioned having installed two fans in the upper back panel, one left the other right.
It draws air from the inside to the outside to expel the heat.
I installed a third fan in the bottom left, near the Y-Sustain, it draws air from outside.
That's it, it works very well for over ten days, every night without problems. Three fans, 12 volt @ 150mA each.
Thank you for your support.

Those look like 60mm fans. Where did you connect them and how? Because I need to do that with my 42" Plasma Gateway

[Tim_1971]

Re: Samsung plasma PN42C450 shut down

The problem I am having with mime is that when I plug it in and turn it on the red power LED comes on but then the power clicks off as well as the power light. Is this due to the power supply board and bad caps?