at a loss with samsung s4051d

[tstokka]

I've replaces all the caps on this board. Getting clicking and 4 flashes on power button of red led. No back light and no sound or screen. heat sinks are all warm when cycling with the clicking except for the lower left one next to the inverter.

Any help would be greatly appreciated

[budm]

Re: at a loss with samsung s4051d

OK, first you need to provide pictures that are in focus, 1st pix is bad, 2nd pix is good.
You need to get the pin labels of those two connectors of the power supply board to go to the main board.
You need to measure each pin DCV when the TV is off and when the power switch is activated.
List each pin number, follow by the name of the pin , and then follow by the DCV reading of the pin so we can see what is/are missing and what is/are not correct.

[tstokka]

Re: at a loss with samsung s4051d

sorry about the picture.

here are the voltages I'm seeing.

The clicking has no effect on any of the voltages on this cable.

what's
written on - measured
the board value
+13 - 13
gnd - good
+5.4 - 5.37
+5.4 - 5.37
+5.4 - 5.37
gnd - good
gnd - good
gnd - good
+12 - 12.19
+12 - 12.19
+12 - 12.19
gnd - good
gnd - good
gnd - good
STB 6.5 - 6.45
P-on/off - 3.78

small connector, all values drop to zero when the relay clicks, then comes back on the next relay cycle

main - power - measured
NC - on/off - .01
ana dim - A-dim - 3.45
pwm - P-dim - 4.94
gnd - gnd - good
sen pwe - E-sync - 5.38

While testing I noticed all the heat cinks were warm except for the one just right of the inverter, with Q1801 and Q1802 attached to it.



Attached are pictures, first is full, next is clockwise starting with upper right

[budm]

Re: at a loss with samsung s4051d

"NC - on/off - .01" The backlights is no getting the BL-ON signal from the main board to turn it on.
Did the signal on this pin ever go up > 2.5VDC?

[tstokka]

Re: at a loss with samsung s4051d

I've been watching it for 10 minutes and max voltage is .08

[budm]

Re: at a loss with samsung s4051d

Well, it is bad, the Voltage should be there when power switch is activated. So you have to find out why the signal is not present.

[tstokka]

Re: at a loss with samsung s4051d

I pulled the main board out and found evidence of moisture on the back of the board. Also the big IC in the center seems to be leaking. Would you suggest just replacing this board?

Thanks

[budm]

Re: at a loss with samsung s4051d

I pulled the main board out and found evidence of moisture on the back of the board. Also the big IC in the center seems to be leaking. Would you suggest just replacing this board?

Thanks

Can we see what is looks like, the moisture and the leak?

[tstokka]

Re: at a loss with samsung s4051d

Pictures attached

[budm]

Re: at a loss with samsung s4051d

The white stuff is the left over from no-clean flux residue.
I am not sure about the black oily stuff on the IC though.
Is this your TV or you bought it used from someone else?

[tstokka]

Re: at a loss with samsung s4051d

I doubt it's flux. looks more like dried milk. No I got it free from craigslist about 2 years ago. It did have 4 caps that were bulging, and I fixed those.

[Dang]

Re: at a loss with samsung s4051d

I'll second the flux residue, seen enough of these to safely say that's what it is, as to the oily residue, that's just leaking from the thermal pad under the heat shield, nothing to worry about.

[tstokka]

Re: at a loss with samsung s4051d

"NC - on/off - .01" The backlights is no getting the BL-ON signal from the main board to turn it on.
Did the signal on this pin ever go up > 2.5VDC?

So, can someone tell me where to look for this missing voltage?

Thanks,

[budm]

Re: at a loss with samsung s4051d

You will have to locate the service manual to get the diagram of the main board or try tracing out the board and draw up the circuit to see where the bl-on pin on the main board is connected to, it should be connected to a switched transistor which is turned on and off by the processor.
Or you can try forcing it on with 1K resistor between BL-ON pin and the STBY POWER supply pin but you MUST remove the bl-on wire going back to the main board first.
Once you have the backlights on if everything else is OK then you should see pictures on the screen and all the other functions should be working if there is no other problem with the main board.