Samsung UE40F5300AK blinking red light

[Fergal22]

Hi,
I have the above tv that just shows a red light blinking twice 5 times, i have taken the back off and all the capacitors seem ok,
When i disconnect the mainboard from the PSU all the led's light up blinking fast but as soon as i reconnect the mainboard back to the power supply i get the red light blinking again twice 5 times,
I have attached pictures of the Mainboard, PSU and a small video (zipped) showing what happens when i disconnect the lead from the psu
Any help would be appreciated

[nomoresonys]

Re: Samsung UE40F5300AK blinking red light

suppose thats usually a backlight issue, test cnm803, see the map/legend near it, report all voltages both in standby and turned on if possible, for example pin #14 ps-on, standby 0 volts, tv on 3.3 volts, etc.

[sintv]

Re: Samsung UE40F5300AK blinking red light

I replaced all leds in a samsung recently but noticed what looked like one that was out giving a black smudge. Lasted for 2 weeks then set went off with blinking led. Turned out half a row was faulty though I couldnt use old leds as they were blue. Replaced faulty led, looked like it had finally went s/c, and set now works. So flashing led is probably faulty backlights.

[Fergal22]

Re: Samsung UE40F5300AK blinking red light

Hi thanks for the quick replies
@nomoresonys
Power on
1 = 7
2 = 2.3
3 = 7
4 = 0
5 = 7
6 = 2.4
8 = 0
9 = 0
10 = 0
11 = 4.36
12 = 4.94
13 = 4.36
14 = 3.0

Power off all read 0 except
14 = 3.0
12 = 4.94

[nomoresonys]

Re: Samsung UE40F5300AK blinking red light

looks like the powerboard isn't turning on fully, maybe unhook backlight connector and do the same test, lets see if there's any change in those voltages.

[Fergal22]

Re: Samsung UE40F5300AK blinking red light

looks like the powerboard isn't turning on fully, maybe unhook backlight connector and do the same test, lets see if there's any change in those voltages.

Hi, sorry for the delay in replying,
Power on with back light connector disconnected
1 = 8.5
2 = 2.95
3 = 8.5
4 = 0
5 = 8.5
6 = 2.1 to 2.85 fluctuating
8 = 0
9 = 0
10 = 0
11 = 5.23
12 = 5.23
13 = 5.23
14 = 3.28

Power off all read 0 except
14 = 3.28
12 = 5.23

[nomoresonys]

Re: Samsung UE40F5300AK blinking red light

try the hairdryer test, with everything plugged in heat up the electrolytic caps for a couple minutes then try the tv, don't wait til it cools off, try it while its still hot.

[Davi.p]

Re: Samsung UE40F5300AK blinking red light

post a picture of the back of power board

[todor]

Re: Samsung UE40F5300AK blinking red light

Hello, with the main board turned off, the 220v power supply must be turned on, the backlight should work normally without blinking. If it blinks, there is a problem with it.

[Fergal22]

Re: Samsung UE40F5300AK blinking red light

try the hairdryer test, with everything plugged in heat up the electrolytic caps for a couple minutes then try the tv, don't wait til it cools off, try it while its still hot.

Tried doing what you suggested but still no joy, back lights still blink for a few seconds then go out

post a picture of the back of power board

Pictures attached as requested

Hello, with the main board turned off, the 220v power supply must be turned on, the backlight should work normally without blinking. If it blinks, there is a problem with it.

So you reckon it's the back lights then?

[todor]

Re: Samsung UE40F5300AK blinking red light

Tried doing what you suggested but still no joy, back lights still blink for a few seconds then go out


Pictures attached as requested


So you reckon it's the back lights then?

if the backlight blinks when the main board is turned off, the backlight is wrong.!!!! It should light up steadily and without flickering. When only the power is turned on and the backlight works, there should be about 380-390 v on the 450v capacitor. If there is a fluctuation or is below 370 in not working properly pfc
!!!This board is finicky and may need to rewrite the emc which is a complicated process

[Davi.p]

Re: Samsung UE40F5300AK blinking red light

Hi, watch the under side on the center left, near the optocoupler in the secondary side there is a small sot23 called QM85, if i can see, that has to be changed, tell me its marking first, don't buy it from chinese market.. if you have spare old unuseful boards take it from there..
before do another little test with the power board alone, test the main board outputs, if them are ok, place a resitor on the b5v , like 5,6ohm 5w, and a light bulb to the b13v, max 30w, if the voltages drops much then the thing to do is confirmed