Samsung UE26D4003BW stand-by light blinking

[Pappel]

Hi!


I've had this TV collecting dust on shelf for a while now, thought i'd give it another look. When i last time worked on it, main board was suspected faulty.
Thought i'd post this here to be sure.

The symptoms are: stand-by light flashing 6 times when plugging the TV in. Nothing comes up and no reaction from the buttons. Caps on the SMPS board seem to be ok.
Also backlight does turn on when mainboard is disconnected.

[Pappel]

Re: Samsung UE26D4003BW stand-by light blinking

I want to try resetting the eeprom, but i'm having trouble identifying the eeprom chip, does seem like it's the "Winbond 25X40BVSIG 1143" (marked with red) or the "ATMLH142 2ECL Y 1G8213" that also seems to have 4 debugging connectors on top of it (marked with yellow).

[tom66]

Re: Samsung UE26D4003BW stand-by light blinking

That is not an EEPROM, it's an SPI flash. It cannot be "reset"
With main board power cable out, check PSU voltages, all good?

[Shinju]

Re: Samsung UE26D4003BW stand-by light blinking

Whoops! wrong thread! (edited)

If you are getting back lights with the main disconnected then its either mainboard or t-con, but this unit looks like the T-con is built into the panel itself so I would bet its a bad mainboard.


Also blinking power LED on Samsungs means nothing :P

[Pappel]

Re: Samsung UE26D4003BW stand-by light blinking

measured the voltages:

1. B13V - 12.81V _____ 2. PWM_DIM - 3.01V
3. B13V - 12.81V _____ 4. N. C/LCD : H -- Sync - 0V
5. Vamp - 12.81V _____ 6. BLU On/Off - 2.1V
7. Vamp 12.81V _____ 8. GND
9. GND _____ 10. GND
11. B5V - 5.18V _____ 12. A5V - 5.18V
13. B5V - 5.18V _____ 14. Power On/Off - 3.07V

[tom66]

Re: Samsung UE26D4003BW stand-by light blinking

Well, the BL ON/OFF command is there... so the backlight SHOULD turn on.

[Pappel]

Re: Samsung UE26D4003BW stand-by light blinking

yes, psu was disconnected from the mainboard and the backlight was on

[selldoor]

Re: Samsung UE26D4003BW stand-by light blinking

Does the back light come on with the main connected but the lvds cable
disconnected.

[Pappel]

Re: Samsung UE26D4003BW stand-by light blinking

if by lvds cable you mean the one from mainboard to t-con, then disconnecting this and leaving mainboard connected to psu doesn't make a difference, same blinks, no backhlight or any sign of life

[budm]

Re: Samsung UE26D4003BW stand-by light blinking

measured the voltages:

1. B13V - 12.81V _____ 2. PWM_DIM - 3.01V
3. B13V - 12.81V _____ 4. N. C/LCD : H -- Sync - 0V
5. Vamp - 12.81V _____ 6. BLU On/Off - 2.1V
7. Vamp 12.81V _____ 8. GND
9. GND _____ 10. GND
11. B5V - 5.18V _____ 12. A5V - 5.18V
13. B5V - 5.18V _____ 14. Power On/Off - 3.07V

Are these Voltage readings taken without the cable connected between the power supply board and the main board?

[Pappel]

Re: Samsung UE26D4003BW stand-by light blinking

yes, that cable was disconnected

[budm]

Re: Samsung UE26D4003BW stand-by light blinking

At this point then we know the power supply and the backlights are OK, but when you have the main board connected the PS_ON is not HI anymore, so you do have main board problem.

[tom66]

Re: Samsung UE26D4003BW stand-by light blinking

Bud, don't Samsung boards use inverted PS ON so a LOW signal is ON, and a HIGH signal is OFF? (Of course Samsung could have changed it for these models...)

[Pappel]

Re: Samsung UE26D4003BW stand-by light blinking

Measured the voltages of the regulators on mainboard:


1. 1117Z 1139DG (pin1 - 0.26V, pin2 - 1.51V, pin3 - 3.26V)
2. N434 950T45 (pin1 - 3.27V, pin2 - 0V, pin3 - 2.5V)
3. 78M09A (pin1 - 12.75V, pin2 - 0V, pin3 - 8.85V)
4. KIA 7805AF 127 (pin1 - 8.84V, pin2 - 0V, pin3 - 4.98V)

[selldoor]

Re: Samsung UE26D4003BW stand-by light blinking

Can you do the voltage tests on the power supply to main again with everything connected.

[Pappel]

Re: Samsung UE26D4003BW stand-by light blinking

measured with everything connected:

1. B13V - 12.82V _____ 2. PWM_DIM - 0.08V
3. B13V - 12.82V _____ 4. N. C/LCD : H -- Sync - 0V
5. Vamp - 12.83V _____ 6. BLU On/Off - 0.04V
7. Vamp - 12.83V _____ 8. GND
9. GND _____ 10. GND
11. B5V - 5.17V _____ 12. A5V - 5.17V
13. B5V - 5.17V _____ 14. Power On/Off - 3.30V

[tom66]

Re: Samsung UE26D4003BW stand-by light blinking

Ok, could you use a resistor from 100-470 ohms in value and connect PS-ON to GND? Then see if 13V/5V go away.

[Pappel]

Re: Samsung UE26D4003BW stand-by light blinking

yes they disappear, only A5V stays at 5.18V

Also the standby light blinking pattern is different

[Pappel]

Re: Samsung UE26D4003BW stand-by light blinking

I noticed the heatsink on the vpu gets very hot, is it suppose to get that hot?

[nenea dani]

Re: Samsung UE26D4003BW stand-by light blinking

It's late but if someone still needs a solution then they should know that the led bar is broken and the circuit breaker protection is working. It is difficult to find the led bar for this size 26 ".