Re: Samsung LN40A630 won't turn on

I decided to start replacing boards since my family was asking me to buy a new tv. I bought a power supply from eBay for $60. Replaced it and no change...I then bought a main board from Encompass Distributors for $100. That fixed the problem and everybody is happy. I would rather spend $160 and get my tv back than pay someone a few hundred to repair or buy a new one for $600. Shame on samsung for building such an unreliable product! A TV should last more than 5 years. While this was broken, we were watching my old tube tv that has lasted more than...

Re: Samsung LN40A630 won't turn on

I didn't find this (or many) main board schematics online. How close are these main board circuits to one another?

When I push the off button on the remote, sometimes the on/off signal drops to 0 volts (the fan stops running) but then jumps back to 3.8v. If i could isolate the failure to one board or the other, I would decide on buying a replacement board.
Any ideas? Thanks

Re: Samsung LN40A630 won't turn on

I unplugged the ir and touch panel boards from the main board. The on/off signal still goes to 3.8v when I plug in the TV. I then tried unplugging the Main board from the ps board. Now the on/off signal stays at 0v. That tells me that the ps isn't pulling this signal high through some ps fault.
Does anyone know where I could find a main board schematic (Bn41-00975c)?

Re: Samsung LN40A630 won't turn on

The buttons are on the touch panel. The touch panel board connects to another smaller board (IR?) board that connects to the main board.

Should i unplug the cable from the touch panel to ir board?

Maybe there is a fault on the ps board that is pulling up the on/off signal to 3.8v. That is an odd voltage.

Re: Samsung LN40A630 won't turn on

I replaced all 11 caps that I bought from shopjimmy. They came as a 'caps replacement kit' for this power supply, bn44-0098a. This change made no difference. One cap was a 0.47 uf, 50v cap that may be in the startup circuit selldoor mentioned. I have the schematic for this ps.

Why would the on/off signal from the main board turn on without me touching the remote or the front switch? If I disconnected the cable from the front switch/ir board from the main board, would anything get damaged? Maybe there is a problem with this front switch...

Re: Samsung LN40A630 won't turn on

Ok...I will replace them all today.

The TV kept takinglonger and longer to turn on. Eventually, it didn't turn on at all and the front LED just keeps blinking. I inspected the power supply caps and they didn't appear to be damaged. I replaced six of them with no change. I measured the PS output voltages and they are close. The TV attempts to turn on when plugged in without hitting the front button or using the remote. The ON/OFF signal to the PS was measured at 3.8V. Any ideas? Thanks in advance for your help.

Re: New Members - please post your introductions here

Hi everyone, I'm Dean, a EE who's been bit by the disposable consumer electronics phenomenon. The problem is that I spent a lot of money on my Samsung flat screen and I don't want to throw it away after five years. So, it looks like this is the place to be for a little guidance on getting my tv back! Thanks in advance for your help.