Maxent MX-50HPT52 has a shaky picture (video inside)

[vizi0n]

Hi everyone,

my 50" plasma tv has a shaky picture. It seems like portions of the content are shifted up/down randomly. It does that on every input. Even the menu is affected by this.

Every board inside this thing is made by Samsung.

Here is a Youtube video : https://www.youtube.com/watch?v=g1cu_vUBDkk

Do you have any suggestion about where to start looking? I checked for leaky/bulged caps but they all seem clean.

Thanks!

[vizi0n]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

Some more info:

Everything was shaky (menu and picture). After changing the logic board (LJ41-03703A) the overlay menu is not shaky anymore but some rows of pixels (1 pixel high) seem like their content is shifted a few pixels to the right, but not beginning at the left side, more like a few inches away from the left side.

The picture is still horrible on all live inputs.

Y-Main : LJ41-04084A
Y-Buffer (up) : LJ41-03882A
Y-Buffer (low) : LJ41-03883A

The overlay menu is somewhat fine on a source with no input, but some pixel rows seem like they have their pixels a bit shifted to the right (by 2-3 pixels). If I switch to a "live" input, the menu is unusable and very dark.

Any leads? Thanks

New Youtube video : https://www.youtube.com/watch?v=p9fozwGNVyw

[vizi0n]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

The voltages on the 10 MOSFETs on the Y-Main are pretty unstable (they vary all the time by about 8-10v on every leg, all of them). Is this a normal behavior?

The 8 diodes are operating normally (flow only in one way)

Every voltage test points (VScan, etc) have all been adjusted to specs according to the number on the label and are very stable at the power supply, and when they enter the Y-Main

[vizi0n]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

Bump ... anyone?

[dick_barton]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

Do you have clear pictures of your boards and the interconnections.

[vizi0n]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

Here, I have attached photos of the boards.

Sorry if its not very clear, I have a shitty lighting in my home workshop

[dick_barton]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

The logic control board is half hidden by the metal chassis. Can you see what the part number is.

[vizi0n]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

It is the first thing I've changed last week. It is LJ41-03703A

[dick_barton]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

May be worth while trying to run the test patterns to see if the fault lies with the mainboard:

Power off
Disconnect the LVDS cable going to the mainboard

Connect the 2 holes marked Ext_Auto_gen with a bit of wire, paperclip etc.

Plug in the tv and turn it on.

Edit
I see they are marked 1,2,3 & 4
Not sure which two to jumper.
Will look further

[vizi0n]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

The only thing I could get was a full white picture when shorting 2 of the pins. The switch on the board would not do anything while in test mode.

Is that what I should be getting?

[dick_barton]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

With the cable disconnected from the mainboard and I believe pins 3 &4 shorted then when you switch back on you should have a screen showing a series of colours or patterns in one after the other. ie, red, green, white, blue etc

https://www.badcaps.net/forum/showth...ght=tom+plasma
There is some info on Samsung control board in this thread

[ReeceyBurger123]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

Sounds like a bad motherboard to me, the control boards for these sets are quite reliable tbh. Try what DB suggested to help confirm might even be something simple like lose or dirty Lvds cable.

[vizi0n]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

Is the LVDS cable the one that goes to the board with all the inputs?

[dick_barton]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

Thats the one. The black cable with the multicoloured wires at the end. Remove the connector carefully.

[vizi0n]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

With legs 3/4 shorted with a jumper and LVDS cable disconnected :

when I turn on the tv I only have a full white picture. The switch (SW2000) doesn't change the pattern on the display)

Large picture of the board available here : https://spares2repair.co.uk/samsung-...sic-logic-main

[dick_barton]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

Here's a video which may be worth following to see if it will bring up the test pattern.

https://www.youtube.com/watch?v=JjrwTZC5nVg

[vizi0n]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

I did all the same tests that are shown in this video. Voltages are good, but I always get the full white picture when jumping 3 and 4 (even when bypassing ps_on) I see that in the video they are actually jumping 3 and 1 so I tried that, but it boots normally.

LED2001 lights up solid while booting, then LED2002 starts flashing rather quickly and LED2001 shuts off.

Youtube video: https://www.youtube.com/watch?v=5UyzvjLCABk

[ReeceyBurger123]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

Replace the mainboard then is what I would do or find a way to factory reset it.

[dick_barton]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

I'm out of ideas so would do as ReeceyBurger123 suggests.

[ReeceyBurger123]

Re: Maxent MX-50HPT52 has a shaky picture (video inside)

Well looking at the video its deffo a Lvds processing fault, if it was a control board fault on the full white screen it would be messing up.