Un55h6350afxza

[jkb242]

Searched for this model here and read some of the threads for insight, always helpful. I don't have the remote for this set to see the setup menu and do not currently have an input source to check the screen. What I determined is the following:

No backlight
No standby light to indicate set is in standby
Measurement thus far:

13.0 vdc standby (set apparently doesn't use 5v standby)
CN803 pins 2,4,6,8 13vdc
390vdc with set on main filter cap.

With system board disconnected from power board set AC connected, backlight are on full screen.
Is there any way to force the set on to bypass the on power command from the system board. I remember on an older set I worked on a few years ago that this command originates on the system board ultimately originating from the main processor. Not sure this is the case with this set.

Was hoping to have the remote before posting to at least see if the setup menu could serve as a video source or if that is needed since the set might generate a text regarding no input is successively powered on. Nothing seen on screen with a very bright led work light to confirm an image. Not sure why the standby light isn't illuminated since I do not have a schematic. Removed power board inspected and measured all HV and low side diodes all normal no caps show classic signs of failure. Picture of both boards interconnected is attached.

Thanks

[jkb242]

Re: Un55h6350afxza

CORRECTION

PINS 2,4,6,8,10 were mistaken for pins 1,3,5,7,9
No measurements were made on even pins due to location measurement difficulty, will attempt then post.

[nomoresonys]

Re: Un55h6350afxza

Try powering on set with one tcon to panel cable connected, check display then do the other side the same, see what is displayed if anything, best practice is make all connections and dis-connections with tv unplugged from power, to avoid any errant surges and such.

[jkb242]

Re: Un55h6350afxza

ADDITIONAL MEASUREMENTS CNM 803
std/by power on
Pin 2 UD. O vdc. 3.30vdc
Pin 4 pwm bl. “. 0 vdc
Pin 6 power on. “. 3.30vdc
Pin 8 ground
Pin 10 ground

When attempting to switch the set off the power on readings remain the same. Unplugging the set is the only way to reset power on readings.

Thanks

[jkb242]

Re: Un55h6350afxza

Try powering on set with one tcon to panel cable connected, check display then do the other side the same, see what is displayed if anything, best practice is make all connections and dis-connections with tv unplugged from power, to avoid any errant surges and such.

Results of above procedure:

Power and system board connected normally with one display connection removed, then AC power connected—-standby light blinks about 6 times then stops remaining unlit, Backlights observed from rear panel appear to be fully on and viewing the screen, no display information but backlight dimly has full screen illuminated. The blue LED associated with the connected port illuminates. After removing AC, allowing time for discharge, same connection was performed with the other T-con to display connection made. Same results observed.

So the T-con board appears NOT to be suspect?

[nomoresonys]

Re: Un55h6350afxza

If you have not, with tv powered on, check and see if you have around 12 volts on each side of the tcon fuse, black probe on chassis ground red probe on each end.

[lotas]

Re: Un55h6350afxza

If you have not, with tv powered on, check and see if you have around 12 volts on each side of the tcon fuse, black probe on chassis ground red probe on each end.

If the TV does not even have a standby indicator, then T-CON and its fuse have nothing to do with it, the problem is in the motherboard.

[nomoresonys]

Re: Un55h6350afxza

That may be so BUT in some tvs, you can turn the standby light off, get it? I do not assume anything.

[nomoresonys]

Re: Un55h6350afxza

I think the problem is the mainboard isn't sending backlight on signal, which was my first thought. Sometimes a simple little test might lead down a different path, it's troubleshooting, assumption is not always good, a simple test of a tcon fuse to at least make sure it isn't blown is something that I always do, no matter the symptoms.

[jkb242]

Re: Un55h6350afxza

I think the problem is the mainboard isn't sending backlight on signal, which was my first thought. Sometimes a simple little test might lead down a different path, it's troubleshooting, assumption is not always good.

I agree entirely in creating certain tests to further define the actual issue. One thing I also noticed after reconnecting the T-Con and with everything back to normal is that when pushing the set power on button, the standby LED blinks 5 times then extinguishes and does not repeat this cycle until the set is unplugged allowed to sit, then the same action could be duplicated. Not sure this offers any real insight. I would asked if there is anyway to apply a constant DC voltage to the BL PWM pin that would mimic the pulse “on duration” equal to approximate mid backlight drive just to get the backlights on. Purely a troubleshooting measure. What's your thoughts regarding this and an idea of the DC bias to use.

Please see the attached picture of the system board noting the numerous board ID numbers. The one listed on the white label and the other one sulked screened on the board circled in red. I've searched EBay for the number on the label but replacement boards that are returned as being available do not match that of the board label of my set. Shop Jimmy has nothing available and appears to now sell everything on E Bay. This board is only 9 years old and well within what is traditionally available from Shop Jimmy I believe. Any sources you could recommend?

Thanks!

[jkb242]

Re: Un55h6350afxza

Sorry I omitted the picture I referenced….

[lotas]

Re: Un55h6350afxza

Your number must be BN94-07845B, BN97-08043A
https://www.tvpartstoday.com/BN94-07...n94-07845b.htm

[nomoresonys]

Re: Un55h6350afxza

https://www.badcaps.net/forum/showth...t=tvpartstoday

[lotas]

Re: Un55h6350afxza

I did not mean to order from this site, I showed what part numbers should be for finding and ordering a motherboard.

[nomoresonys]

Re: Un55h6350afxza

That board is for ver. UH02, his ver. is UH01, part number is different.

[lotas]

Re: Un55h6350afxza

It does not matter.

[nomoresonys]

Re: Un55h6350afxza

I'll take your word for it, I did not research it.

[lotas]

Re: Un55h6350afxza

You don’t have to look for the motherboard if there is a programmer, then you need to read the data (dumps) from 25Q40 and 24C512, and if the software fails in them, then you can restore it.

[jkb242]

Re: Un55h6350afxza

Your number must be BN94-07845B, BN97-08043A
https://www.tvpartstoday.com/BN94-07...n94-07845b.htm

Thanks indeed for the assistance. The board model number on the sticker shows the exact board for this set to be BN-07259E which was in stock at the supplier recommended. I appreciate being told about this source as I was unaware of them. I ordered the exact board and agree that the sys board would seem to be the culprit given no other more classical failures. Much thanks will provide feedback when board is replaced.

Thanks again for the assistance!

[jkb242]

Re: Un55h6350afxza

You don't have to look for the motherboard if there is a programmer, then you need to read the data (dumps) from 25Q40 and 24C512, and if the software fails in them, then you can restore it.

Are you saying this could be a programming issue that would not be addressed by a replacement board? If so I need to know ASAP as I do not have a programmer or reader. Do any of the replacement boards require programming?

Thanks again!