Samsung LA46B530 4 blinks

[spintop]

Need some help from you guys here.
TV only show power led lights 4 blinks when switch on. No video or sound.

TV model is Samsung LA46B530
PS board is BN44-00265b

When plugged into power but not switched ON

5v_det : 0v
inv-on : 5v
13v : 0v
5.1v : 5v
13v : 0v
sb : 5v
ps : 0v

12v : 0v
FD : 0v
LD : 0v



when switched ON

5v_det : 0v
inv-on : 0v
13v : 12v
5.1v : 0v
13v : 12v
sb : 5v
ps : 0v

12v : 12v
FD : 0v
LD : 12v

any advice is appreciated. thanks

[budm]

Re: Samsung LA46B530 4 blinks

The white fuse on the middle of the board good?
Are you sure that you count and check the pin of the connector correctly?
You are showing PS (PS-ON) of 0V so there is no way you can have the Switched 13V when TV is turned on. Are you sure it is not 0.7V when TV is ON?
The INV-ON is also not right, it should be <1V when TV is OFF, >2V when TV is ON.
I also do not see the PWM reading.
The Power supply-Inverter board combo has pull-up resistors for doing the self test, so if you disconnect the cable between the power supply and the main board, the backlights should come on and stay on the minute the plug the TV into the outlet.

[spintop]

Re: Samsung LA46B530 4 blinks

i did a recheck. all fuses are OK.
u are right.
PS is indeed 0.7v when switch ON.
Inv_on is still 0v when switch ON.
but i do have 13v. when switch ON. strange.

e-pwm 3.1v, when switch on
i-pwm 0v, when switch on

no light even with cable disconnected.

later i will try to pull-high at PS, to turn on the supply. to see if ps board is working

The white fuse on the middle of the board good?
Are you sure that you count and check the pin of the connector correctly?
You are showing PS (PS-ON) of 0V so there is no way you can have the Switched 13V when TV is turned on. Are you sure it is not 0.7V when TV is ON?
The INV-ON is also not right, it should be <1V when TV is OFF, >2V when TV is ON.
I also do not see the PWM reading.
The Power supply-Inverter board combo has pull-up resistors for doing the self test, so if you disconnect the cable between the power supply and the main board, the backlights should come on and stay on the minute the plug the TV into the outlet.

[budm]

Re: Samsung LA46B530 4 blinks

On this power supply/inverter board, 0.7V is = HIGH and it is the correct Voltage for PS-ON to turn on the power supply, that is why you are getting the switched 13V, 0V = OFF for this board, so your PS-ON is OK, no need to jump the PS-ON with the resistor since the resistor is already in place.
So now you need to check the INV_ON pin to see what DCV you have when it is not connected to the main board.
You also need to check the DCV between the two legs of the main cap to see if you have close to 400VDC, you will do all of this without having the cable between the power supply board and the main board in place, but you must have the balancer board connected still.

[spintop]

Re: Samsung LA46B530 4 blinks

oh thanks for your explanation. thats explain why 13v is there.
so something is telling the main board to switch inv_on from 5.1v to 0v when turn on. I didnt find any faulty diodes or mosfet.


with cable off, i got
inv_on : 3.7v
main cap : 393v

On this power supply/inverter board, 0.7V is = HIGH and it is the correct Voltage for PS-ON to turn on the power supply, that is why you are getting the switched 13V, 0V = OFF for this board, so your PS-ON is OK, no need to jump the PS-ON with the resistor since the resistor is already in place.
So now you need to check the INV_ON pin to see what DCV you have when it is not connected to the main board.
You also need to check the DCV between the two legs of the main cap to see if you have close to 400VDC, you will do all of this without having the cable between the power supply board and the main board in place, but you must have the balancer board connected still.

[budm]

Re: Samsung LA46B530 4 blinks

oh thanks for your explanation. thats explain why 13v is there.
so something is telling the main board to switch inv_on from 5.1v to 0v when turn on. I didnt find any faulty diodes or mosfet.


with cable off, i got
inv_on : 3.7v
main cap : 393v

The backlights should be on right now when you do not have the cable connected to the main board.
If you look at the diagram page 1 you will see pull-up resistor RI856 for the INV_ON pin, the output side of RI856 is connected to the RI874, the output of RI874 is connected to the ENA (ENABLE) pin 7 of the Inverter PWM ICI801, there is also a switched transistor QI818 to ground out the ENA signal if the Boosted Voltage from the PFC circuit is too low (your is OK at this point because you are getting 393VDC).
So right now you need to find out if you do have >2.5V on the ENA pin of the ICI801 or not.
You also need to check the DC Blocker/coupling cap CI804 (0.68uF 500V) to make sure it is OK (no bulging, the capacitance is still corect, etc.).

[spintop]

Re: Samsung LA46B530 4 blinks

i get ENA at 2.4v and inv_on 3.7v
not sure if that is enough to trigger it. otherwise will have to force 2.5v from somewhere
i am still not getting any backlight at all

CI804 looks normal. but i dont have equipment to check capacitance now

[budm]

Re: Samsung LA46B530 4 blinks

i get ENA at 2.4v and inv_on 3.7v
not sure if that is enough to trigger it. otherwise will have to force 2.5v from somewhere
i am still not getting any backlight at all

CI804 looks normal. but i dont have equipment to check capacitance now

The signal level is fine.
BTW, do you notice if the lamps even come on for seconds if you look at the back of the LCD panel in the dark room?
The LD error signal should have gone LOW (<10V) if the lamps did not conduct, but it is at 12V right now, something is not quite right.

[spintop]

Re: Samsung LA46B530 4 blinks

i dont see any lights at all not even a blink.
LD still 12v.

will recheck all the components again later.

The signal level is fine.
BTW, do you notice if the lamps even come on for seconds if you look at the back of the LCD panel in the dark room?
The LD error signal should have gone LOW (<10V) if the lamps did not conduct, but it is at 12V right now, something is not quite right.

[dick_barton]

Re: Samsung LA46B530 4 blinks

If the LD (lamp detect error) is not showing a fault then are you certain that the backlights are not on. You may see a blackish/blue screen from viewing the front of the TV but should see some light through the holes when viewing the backpanel.

[budm]

Re: Samsung LA46B530 4 blinks

OK, I just read the SONY training manual (SONY/SAMSUNG uses the same topology for the inverter/balancer circuit).
The LD is normally HIGH (>11VDC), the LD will go low if not ALL the LAMPS are ON when HIGH Voltage from the Inverter transformer is present, if the high Voltage is not present then there will be no error signal from the Balancer transformer to produce an output to trip the comparator circuit that will make the LD line goes low.
So what we are seeing right now at the LD pin is normal, something else in the inverter section is bad.
So we need to find out if the ICI801 (LX6508) is getting the 12VDC on Vin pin 1 to run or nor and if there is any activities at the drive output pins 13, 15. OP will need scope for testing.
Also need to check to see if there is any activity in the GATE drive transformer TI8088 circuit, check CI884 capacitance.
The CI804 capacitance still need to be verify but OP does not have the tool to test capacitance.
At this point needs to get new board.

[spintop]

Re: Samsung LA46B530 4 blinks

looks like this tv getting complicated to repair.
anyway great thanks to budm and others for the advice.

can i say i need to source for the supply board power first?

[budm]

Re: Samsung LA46B530 4 blinks

What country are you in?

[spintop]

Re: Samsung LA46B530 4 blinks

vietnam

[spintop]

Re: Samsung LA46B530 4 blinks

anyone got datasheet for LX6503s ccfl controller?
google cant find any. want to know what voltages expected for pin9 (v-sns) and pin10(i-sns). meanwhile awaiting for part CI804 (0.68u 500v)

I have taken out power board (just ac power, not other cables) measured lx6503 pin.
suspecting Driver 1&2 is not functional, with det_5v at 0v all times.
would like to manually control i_sns & v_sns.

lx6503 chip
1(vin) - 10.2v
2(c_r) - 1.5v
3(c_t) - 4.8v
4(c_b) - 4.5v
5(brt_d) - 5.1v
6(brt_a) - 1.7v
7(enable) - 2.5v
8(sync) - 0
9(v_sync) - 4.3v
10(i_sync) - 0
11 to 15 -0v <== driver1 & 2
16(Vdd) - 5.2v

on the connector side
ps_on is 0.7v
inv on/off is 3.9v
det_5v is 0
5.2v is 5v
13v is 12.9v
epwm is 5.1v
stb5.3v 5v