Samsung LN55B640R3FXZA issue after power outage

[bfason]

Good Morning all,

I have a Samsung LN55B640R3FXZA that will not power on. We had a power outage and everything came back on except the TV. The red standby light comes on but once you press the power button on the remote it goes out and nothing happens. No power on tune, no audio, just a black screen. I originally thought it was the PS but didn't see any visible damage. When the ribbon cable is removed between board with all the inputs/outputs (logic board?) and the PS the screen lights up.

I know very little about electronics in general but would like to know more and any help would be greatly appreciated.

Thanks!

[johnboy1313]

Re: Samsung LN55B640R3FXZA issue after power outage

When the ribbon cable is removed between board with all the inputs/outputs (logic board?) and the PS the screen lights up.

The input board is called the mainboard. If your screen lights up with the main disconnected from the power supply (PSU), your PSU is fine. Your mainboard is probably not. Before you replace the mainboard, unplug the orange ribbon that connects the T-Con board to the main and see if the set will come up with the main connected to the PSU.

[bammbammfran]

Re: Samsung LN55B640R3FXZA issue after power outage

Based on the way that most systems work, your unit should not power on and light the screen if the main (input) board is disconnected from the power supply.Most power supplies need the main board to tell it to turn on the second part of the power supply to light the screen.
Is there a PS-On or PWR-on wire marked at the power supply plug that leads to the main board ?

[budm]

Re: Samsung LN55B640R3FXZA issue after power outage

Most of the newer power supply board has pull-up resistors built-into the power supply board so you do not have to do the force on using the resistors, they made it easier to narrow down the problems for techs in the field. The main board will keep the lines low and release them when TV is powered up.
For example:

[bammbammfran]

Re: Samsung LN55B640R3FXZA issue after power outage

Most of the newer power supply board has pull-up resistors built-into the power supply board so you do not have to do the force on using the resistors, they made it easier to narrow down the problems for techs in the field. The main board will keep the lines low and release them when TV is powered up.
For example:

Why would they build something that is easier to troubleshoot !! Doesn't sound like any manufacturer I have run into yet. Especially Samsung !!

[budm]

Re: Samsung LN55B640R3FXZA issue after power outage

They probably getting tire of having the Tech spending too much time in the house trying to force the board on with tiny resistors or carry a bunch of connectors with resistors on them. Same thing with blinking error codes.

[bfason]

Re: Samsung LN55B640R3FXZA issue after power outage

First of all thanks for all the replies!

Sorry its taken me a bit to reply.

I removed the orange cable from the mainboard and still have the same symptoms as before.power tune doesn't play and the standby light goes off.

Anything else I can do to narrow down the problem?

[budm]

Re: Samsung LN55B640R3FXZA issue after power outage

May be the main board got scrambled when you had power outage, so far it looks like the main board is the problem. With the TV off, hit the mute, 1, 8, 2, and power button on the remote in sequence to see if you can get to the factory setup menu to come up.

[bfason]

Re: Samsung LN55B640R3FXZA issue after power outage

Ok tried the factory reset with no results, the standby light stayed on but no audio or display.

[budm]

Re: Samsung LN55B640R3FXZA issue after power outage

You can do visual inspect of the main board to see if there is any damaged/burnt component, also look at shopjimmy to see how much the new board will be.

[bfason]

Re: Samsung LN55B640R3FXZA issue after power outage

Thanks for all the help, I couldn't find the logic board on shopjimmy but was able to get one on Ebay fairly cheap and the tv is back together and working.

Great group here and very helpful.

[budm]

Re: Samsung LN55B640R3FXZA issue after power outage

Great! and thanks for the follow-up