Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

The meter reads everything else fine so it's not the meter, if that reading is off it's a problem somewhere. My non-auto range meter couldnt pick it up.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

You have to leave the meter in place and then turn the TV on, the Voltage will only appear very short time because it goes into shut down, every time you move to the next test pad, you will have to turn the TV off and turn it back on, it will be a lot of turning on and off to test ALL those test points.
How about the Voltage reading of that LD pin?

Did exactly that, there's nothing, the ld is 12.19 or 13.9.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

Probably need to test CN801.

[budm]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

It cannot be nothing on the diode when the backlights flash on, impossible.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

Was suspecting that I needed an auto rage meter, luckily have one, tested them from bottom up, the top one went like 1.8 way high, on the last one the top one that is, the backlight went on and stayed on, that's where I'm at now.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

That is backlight stayed on for about 1 or 2 minutes.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

Can't seem to duplicate the baclight on for 1 or 2 minutes tho. during that time was able to see a no signal text display, normal cuz no antenna connected.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

readings fluctuate, one time the second from top said 1.8 then next time it said .4, the 5th one from the top always says .8, that may be the problem area. Twice on this test the backligkt stayed on for about 2 minutes. each time while testing a different transformer as in not the same one then tried that same one and it didn't stay on only for a half second or so.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

What is the power supply board P/N?
BN44- ??????
If I remember correctly, this power supply is know for having low PFC Voltage due to bad feedback resistor network.

Do you think these symptoms point towards the low PFC you mention here?

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

http://www.shopjimmy.com/auo-19-40t0...t-inverter.htm That's a way better picture than I could ever get, they call it a backlight inverter.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

http://www.shopjimmy.com/auo-19-40t0...t-inverter.htm That's a way better picture than I could ever get, they call it a backlight inverter.

Thinking about trying the jumper on the 5th one from left to right, if I gathered the right info from the video, it's the 1st and 3rd test pads right in front of the transformer from left to right.

[budm]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

http://www.shopjimmy.com/auo-19-40t0...t-inverter.htm That's a way better picture than I could ever get, they call it a backlight inverter.

That is the mistake by SJ.

[budm]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

Do you think these symptoms point towards the low PFC you mention here?

Nope, you have over 380VDC.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

Nope, you have over 380VDC.

Ok thanks.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

Did the jumper, Think it's fixed, thought it was transformer 5, but it was 1, from the top so the top 1, those tests are good but can be confusing, almost jumped the wrong one, the best test to me was the ground out, that pin pointed it, one tip, use as small of gauge wire for the jumper as is allowed, makes for easier soldering in place, the clearance between pads is small. THANKS for the help maxvalutech and budm

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

That is the mistake by SJ.

Ok

[budm]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

So you do have one bad lamp, so more likely the other will follow, you should should turn down the backlights level so the CCFL will be driven hard so it will extend the lights a little more.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

So you do have one bad lamp, so more likely the other will follow, you should should turn down the backlights level so the CCFL will be driven hard so it will extend the lights a little more.

Seems like the lamp is bad, yep turned it way down, as you would expect it was on maximum, not sure, the guy in the video said the customer should get many more years of use.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

Another thing I noticed, this tv has a metal back and it looks burned where the power board is, the main board, all along the balancer and the whole perimeter, makes me think that the metal back is too close to the boards, poor ventilation or they hung it flat against a wall.

[nomoresonys]

Re: Samsung LN40C650L1FXZA Backlight flash no voltage on 450 v. filter caps.

Another thing I noticed, this tv has a metal back and it looks burned where the power board is, the main board, all along the balancer and the whole perimeter, makes me think that the metal back is too close to the boards, poor ventilation or they hung it flat against a wall.

plus the backlights were at 100 percent. my advice is drill a bunch of ventilation holes in the back, but it still leaves the main board right against the metal back, very poor design from samsung engineers.