Samsung PN51E450A1FXZA won't turn on, no standby light

[calanan]

Looking for help with a Samsung PN51E450A1FXZA that won't power on and has no standby light. TV belongs to my mother, who says it worked fine until her cat messed around with the power strip into which it was connected knocking the strip's plug out of the socket...she heard a short zap, and ever since it's been dead.

Visual inspection shows no obvious issues, power cord is good, no puffed capacitors, no scorching, etc.

Power supply is model BN44-00509B. With power supply connectors removed I see the following A/C voltages:

Connector CN801 (main board) shows 10V on pin 1 (labeled PS_ON), 12.7V on pin 2 (labeled A5V), and 0V on all others.
Connector CN802 (X-Buffer board) shows 10V on pin 2 (labeled PS_ON), 0V on all others).

Would like to know if this is normal and if so what I should check next. If not does this already indicate that the problem is the power supply?

- mike

[tvtimmy]

Re: Samsung PN51E450A1FXZA won't turn on, no standby light

Im 90% sure its a bad mainboard. There are many versions that will work for this tv. Check shopjimmy for compatible boards, then shop on ebay for a cheap one.

[calanan]

Re: Samsung PN51E450A1FXZA won't turn on, no standby light

Thanks, is there an easy way to determine if this mainboard is bad, eg expected voltages at certain pins?

[R_J]

Re: Samsung PN51E450A1FXZA won't turn on, no standby light

all the voltages on those plugs should be measured in DC not A/C
CN801 should have +5 volts DC on pin2 PS_ON should change when the power button is pressed and the tv comes out of standby, then the other voltages should appear

[tvtimmy]

Re: Samsung PN51E450A1FXZA won't turn on, no standby light

Unplug the cable going from the mainboard to the control board. On the control board there are 4 copper holes marked 1,2,3,4. Put a paperclip in 3&4, then turn on tv. You might see the test patterns. If so, the mainboard is bad. I still feel it is the problem with your set not showing any life.

[calanan]

Re: Samsung PN51E450A1FXZA won't turn on, no standby light

Thanks, I tried that but get nothing at all, no standby light, no clicking, no display, etc.

[calanan]

Re: Samsung PN51E450A1FXZA won't turn on, no standby light

I ended up buying this kit from ShopJimmy, which has all the boards and began swapping them in order of suspected damage.

When I swapped the main board I finally got power and could hear the turn-on melody but had no picture. I then swapped the control board and finally got a picture but it has a broken vertical line of pixels at the right end of the display the appear green on a black background and purple against a white background. I've attached photos.

I tried swapping the Y scan drive to fix that but when I do I get no picture at all (even with multiple attempts to seat it and the ribbons) so I suspect I have one that's DOA from ShopJimmy.

For kicks I also swapped the X/Y Main and X Buffer boards but those didn't make a difference; I didn't bother swapping the power supply as that seems fine.

But those aside, from what I'm reading this pixel problem seems more of an issue with the panel itself or even something in those ribbons than with any of the boards. Does anyone here know for sure?

[freakaftr8]

Re: Samsung PN51E450A1FXZA won't turn on, no standby light

That is Not repairable. That is a problem with the chip film ribbon drivers on the bottom of the plasma display panel