Samsung LE32B350F1W starting PROBLEM

[mr.cool]

My dear friends !

I have a Samsung TV with strange symptoms ...

Model : LE32B350F1W
Power supply : bn44-00289a

When i connect to AC, there is no red power led, no picture, no backlight, no sound !


BUT ... I have :
5,3 Volt stable
and 13 Volt unstable (varies between 13V and 21V)
(The voltage on the MainCap CP811 (100µ/450V) also varies between 300V and 390V )
..and the heatsink on the mainboard becomes warm.

With "unstable" i mean that the voltage is rising and falling permanently!!
When i warm up the capacitors (i marked with green) the Tv starts and all is fine !
I changed the caps but unfortunately the problem persists....
But when i disconnect the AC for 5 sec.---- same Shit same Station !
In "cold state" i unplug CN802 the backlight comes on the 13V and the 5,3V are stable .

CN802
Normally(warmed up capacitors)
Main Cap voltage is stable with 395V
1. Power On/Off 2,2V
2. 5,3V
3. GND
4. 13V
5. GND
6. GND
7. 5,3V
8. 5,3V
9. GND
10. 13V
11. 13V
12. InverterOn/Off 5,1V
13. E-PWM 3,1V
14. DET_5V 2,5V
15. GND
16. GND
CN802 plugged in BUT NOT WARMED UP !:
Voltage is rising up and down
Main Cap voltage varies from 300V <--> 390V
1. Power On/Off 2,2V <--> 0V
2. 5,3V stable
3. GND
4. 13V <--> 21V
5. GND
6. GND
7. 5,3V stable
8. 5,3V stable
9. GND
10. 13V <--> 21V
11. 13V <--> 21V
12. InverterOn/Off 0,17V <--> 0V
13. E-PWM 1,6V <--> 0V
14. DET_5V 0,01V <--> 0V
15. GND
16. GND

No diodes or transistors are shorted.

The last experiment was...:
When the Tv is "cold" and i remove pin12 and pin13 of CN802 the Tv starts with picture and sound.
BUT when i power off with the remote control the backlight still is on and the standby led lights.

Any Idea my friends ?

Best regards...!

[mr.cool]

Re: Samsung LE32B350F1W starting PROBLEM

Oooops i forgot the pics ....

1. These are the caps that i warmed up for starting the set !
2. Power supply
3. The Tv opened (Mainboard & Power supply)

[budm]

Re: Samsung LE32B350F1W starting PROBLEM

It looks to me that the STBY Voltage is stable to feed the main baord but the PS-ON signal is cycling on and off so the PFC and the rest of the power supplies that are controlled by the PS-ON is just cycling up and down. You have main board problem.

[mr.cool]

Re: Samsung LE32B350F1W starting PROBLEM

Hmmmm, yes i think so....
But whats the reason that the set is starting when i warm up the caps ? (1000uF/25V)
Unfortunately i have no SM from the mainboard :o(

The SM from the Power supply....

[victor_cj]

Re: Samsung LE32B350F1W starting PROBLEM

BN44-00289A with soldering problem or main board with 24C512 eeprom problem.

[budm]

Re: Samsung LE32B350F1W starting PROBLEM

Those 1000uF are for the 13V power supply.
"10. 13V <--> 21V
11. 13V <--> 21V"
So just to be sure, you are saying that the 13V jumps up to 21V? and for sure that the 5.3V is stable since the 5V and the 13V are generated by the same power transformer. ICM852 is the 13V regulator IC, so I may be when you heat up around those caps you may have also heated up the IC too.

Try replacing them and see what happen.

[steviewonder]

Re: Samsung LE32B350F1W starting PROBLEM

Nope, not the mainboard.How could the 13v supply rise to 21v if this was the case? it's strictly regulated by the psu, not ruled by the motherboard.
more likely one of the much smaller caps on the psu at fault.try heating each one up individually, (there aren't many)

[mr.cool]

Re: Samsung LE32B350F1W starting PROBLEM

My friends !
I know that the 4 caps are for 13V ! I changed all 4 caps but same problem!
I also warmed up the 4 new caps ---> same shit same....
I heated up the Ic´s , all the other caps but ..... nothing happens.
I also changed the little caps on primary side of the psu !

A little correction of the voltages...
Yes the 13V rises up to 21V ...in the next half second again to 13V.
This goes in steps. 13 - 15 - 13- 16 -13 - 18 - 13 - 21.......and so on.

The 5,3V sometimes varies to 4,75V !

[victor_cj]

Re: Samsung LE32B350F1W starting PROBLEM

The main board has a problem on 5,3V feed usually eeprom is faulty, i had this problem and the 13V feed rises to 16,9V.

[mr.cool]

Re: Samsung LE32B350F1W starting PROBLEM

@victor_cj:
Was it the same Tv ? (le**B350f1w)
Did your set turn on ?
What did you do with the Eeproms?
Do you have a SM from Mainboard ? (Main AV - BN41-01207B - BN94-03095H - SURVIVAL_DVB)
Eeprom = MX25L6405D (64Mbit 16Pin)

[victor_cj]

Re: Samsung LE32B350F1W starting PROBLEM

Same tv LE32B350F1W. MX25L6405D is flash spi, 24C512 is the eeprom we replaced, take a look at my pictures, SAM_8523.

[mr.cool]

Re: Samsung LE32B350F1W starting PROBLEM

Oh yes ! Sorry its a spi flash !
Is the 24c512 defective or the soft on it ?

[mr.cool]

Re: Samsung LE32B350F1W starting PROBLEM

I read the atmlh922....
there are the names of the channels i stored !
Please explain for what this is EEPROM responsible?

[budm]

Re: Samsung LE32B350F1W starting PROBLEM

The main board has a problem on 5,3V feed usually eeprom is faulty, i had this problem and the 13V feed rises to 16,9V.

I do not see the relationship between the 5.3V feeding the main board and the 13V Regulator IC, if the out put is no longer regulated to 13V and putting out 16.9V then it sounds more like regulator problems.

[mr.cool]

Re: Samsung LE32B350F1W starting PROBLEM

.... so, i tested the eeprom.. and leave it blank (without soft) !
I resoldered it and started the Tv with my hair dryer !
The only effect was, that i had to change all settings NEW !! (language, channels...and so on !!) LOL
Now ! ...definitely this eeprom has nothing to do with the start cycle !!
The voltage on the regulator output can be so high as the input because its not a fixed regulator like a LM78**....so the adjust input varies too, right ?
If the voltage before the regulator is too high than its NOT a problem of the mainboard.

[budm]

Re: Samsung LE32B350F1W starting PROBLEM

It is adjustable LDO regulator, the resistor network on pin 4 of the IC set the output Voltage, similar to LM1117 series. For the regulator to regulate you need to have minimum Vin-Vout on the device.
The regulator may be Oscillating or bad resistor network.
BTW, sinc eyou can warm that area to make it function, then may be you should inspect the soldering works and connection real close.

[mr.cool]

Re: Samsung LE32B350F1W starting PROBLEM

I will try....
thank you !

[budm]

Re: Samsung LE32B350F1W starting PROBLEM

Correction, this is the correct spec for the IC. The one in post 16 is for KIA278R000pi which only has 10V Vin max.

[victor_cj]

Re: Samsung LE32B350F1W starting PROBLEM

Oh yes ! Sorry its a spi flash !
Is the 24c512 defective or the soft on it ?

In my case was defective, this was in october 2013.

[mr.cool]

Re: Samsung LE32B350F1W starting PROBLEM

Hello :o)
I´m still waiting for the KIA278R00P1....
I´m reporting further when i get the LDO....