Samsung BN44-00369B

[stoian_93]

Hello, folks!

I have an Samsung LCD TV with defective powerboard BN44-00369B.
First, it was a defective STF13NM60N transistor (QP801), so I replaced it. But now, there are no Backlight and picture.
There is no power to CNI801 output, even no power to the TI801S.
To the CNI803 there are:
Pin / Voltage
1 (12V) / 12.88 V
2 (GND) / -
3 (GND) / -
4 (LD) / 0.00 V

[nomoresonys]

Re: Samsung BN44-00369B

test QP801 see if it is still ok.

[stoian_93]

Re: Samsung BN44-00369B

test QP801 see if it is still ok.

You mean the same transistor - it's okay. TV is working, there is sound, stand by, on/off remote controling, on/off sound, but no screen and backlight.

[dskall]

Re: Samsung BN44-00369B

What is your voltage across main capacitor?

[nomoresonys]

Re: Samsung BN44-00369B

plus, check ALL voltages on CNM802, black probe on chassis metal ground, red probe on each pin, check in standby[tv plugged in but not turned on] take note, leaving probes in place power up tv, take note, report both conditions as in, pin 1 off 0 volts on 13 volts etc, do it for every pin.

[lotas]

Re: Samsung BN44-00369B

BN44-00369B service manual

[nomoresonys]

Re: Samsung BN44-00369B

example of testing there: https://www.youtube.com/watch?v=ocqnqmBxiqY

[R_J]

Re: Samsung BN44-00369B

If QP801 was shorted, RP817 will be open, and if RP817 goes open, ICP801 almost always is damaged as well. You also need to check the gate circuit, RP804, DP803, RP805.

[stoian_93]

Re: Samsung BN44-00369B

If QP801 was shorted, RP817 will be open, and if RP817 goes open, ICP801 almost always is damaged as well. You also need to check the gate circuit, RP804, DP803, RP805.

Hello!
I checked:
Element - Original - Checked
RF817 - 10 KOhm - 9.92K
RP804 - 68 Ohm - 1.1/1.2 MOhm (not seem good)
RP805 - 27 Ohm - 1.2/1/3 MOhm (not seem good)
DP803 - multicet shows 398 Ohm, is it fine?
About ICP801 - there are no FAN7530 in stock here, what analog can I get?

[nomoresonys]

Re: Samsung BN44-00369B

yep looks like those 2 not seem good ones are open/bad. RF817 is ok, DP 803 seems very low.

[nomoresonys]

Re: Samsung BN44-00369B

can we get a good clear picture of this board? working in the blind here.

[stoian_93]

Re: Samsung BN44-00369B

can we get a good clear picture of this board? working in the blind here.

Sure. Here they are.

[nomoresonys]

Re: Samsung BN44-00369B

for good measure make sure Q802 and the other one near it are not shorted.

[nomoresonys]

Re: Samsung BN44-00369B

some of those solder joints don't look too good, examples of bad joints there: https://www.google.com/search?q=bad+...ih=607&dpr=1.5

[stoian_93]

Re: Samsung BN44-00369B

some of those solder joints don't look too good, examples of bad joints there: https://www.google.com/search?q=bad+...ih=607&dpr=1.5

If you're talking about the transistor joints, they're like this because the paths were cutted when father tried to replace it, so I joined the paths this way after him.

[nomoresonys]

Re: Samsung BN44-00369B

ok, theres some other suspect joints look them over carefully, make sure none are cracked or loose etc. refer to the images if needed.

[stoian_93]

Re: Samsung BN44-00369B

for good measure make sure Q802 and the other one near it are not shorted.

I checked both, not shorted. Found FAN7530 (ICP801), RP804, RP805, DP803 in stock, purchased and gonna replace and see what happen.

[nomoresonys]

Re: Samsung BN44-00369B

that might do it, if you look at some of your joints they could very easily be cracked and need re-soldered, the examples of cracked joints are in the images linked.

[stoian_93]

Re: Samsung BN44-00369B

that might do it, if you look at some of your joints they could very easily be cracked and need re-soldered, the examples of cracked joints are in the images linked.

This is also a task to do when replacing the elements - to look and resolder the bad joints.

[nomoresonys]

Re: Samsung BN44-00369B

why not, Im done with this, thanks for your help.