samsung LN-S4041D

[martino]

Hello there.....
When turning on TV you hear the relay click,then the red led flashes 4 times,then it repeats itself in that cycle forever(click/4 flashes,click...etc...)
The owner had replaced two caps on the PSU and problem persisted...
I checked all voltages on CNM801 and they are correct....

I was looking for a quick test from samsung but couldn't find it
On another samsung if you unplug CNM801 and power up the TV the backlight comes on,I did this on this TV but nothing happened..

After long reading I learned that most cases it's caps on PSU but in the odd case it's the main board...how can I test to be sure what board to replace/repair??

[Caleb]

Re: samsung LN-S4041D

Check esr on those caps in your 3rd pic, just because they were replaced doesnt mean the new ones are up to snuff. What brand and series are the replacements?

[budm]

Re: samsung LN-S4041D

This power supply board does not have built-in pull-up resistors for the PS_ON or for the BL_ON line so you cannot expect the backlights to come on by disconnect the cable between the power supply and the main board, you will have to force them on using 1K resistors and the STBY power supply section.

[martino]

Re: samsung LN-S4041D

The caps are made by CKEM 25v 1000uf B105c.How can I check the esr on them??

budm,would you be so kind to explain that forcing on in a little more detail? I tried to read the scematics but can't figure it out

[Caleb]

Re: samsung LN-S4041D

You would need an esr meter
Im not familiar with those caps, couldnt find anything in a quick google search. Maybe someone will chime in who knows what they might be.

Ill defer to Budm on the power supply, usually to power on your supply you need to place a 1k resistor between your 5v standby circuit and the ps on pin, same thing for the bl on. On some power supplies you have to pull down the voltage to activate.

+5v--------==1k==-------ps on
+5v--------==1k==-------bl on

[martino]

Re: samsung LN-S4041D

Ok,and I should do that with the main board unplugged I assume?

[Caleb]

Re: samsung LN-S4041D

Yes, Your trying to diagnose if the power supply is ok by forcing it to come on. If it comes on and you have proper voltages and backlights you can assume its the main that isnt functioning.

[tom66]

Re: samsung LN-S4041D

Yes.

[martino]

Re: samsung LN-S4041D

So,I jumped stb 6.5v to P-on/off on connector cnm801 with main unplugged.
On cnm801 I get all the proper voltages.
On cni801(see pic) I get:
12Vdc= 12.04 volts
FB = 0.00 volts
GND = 0.00 volts (duh)
PR-1 = 0.00 volts
L-DECT=11.94 volts

Now,before I hook up my meter to cni802 and cni801(see pic) I like to ask how much voltage I can expect between the 2,also is that AC or DC??

The powersupply does not cycle through it's on/off cycle with ps on jumped(assuming its the main board doing the cycling) but I'm not getting a backlight on.
Is cni803 (see pic) responsible for turning on the backlight?? cni803 goes to the mainboard...

[martino]

Re: samsung LN-S4041D

Forgot to mention,cni801,cni802 and cni803 all go to a what looks like a buffer board? on the left side of the screen..(see pic)

[tom66]

Re: samsung LN-S4041D

Those are the lamp inverter connectors.
The voltages look good.

[martino]

Re: samsung LN-S4041D

So main board is suspect? Anything I can test or EEPROM reset?

[Caleb]

Re: samsung LN-S4041D

Can you check the voltage on the black wire on cni803, I believe that is where the bl on should be coming from the main board. Dont try to test 802 or 803 as they will have thousands of volts when they are on

[martino]

Re: samsung LN-S4041D

had a suspicion that 802 and 803 would blow my 1000volt meter to pieces,so happy i didnt measure that lol
I get no voltage on that black wire while the main board does it's cycling...
Can I jumper that with the same 1k jumper to the standby 6 volts???

[martino]

Re: samsung LN-S4041D

So,with my 1k jumper to P-on and a jumper to the black wire on cni803(mainboard disconnected) I get the back light on and all voltages are there from the PSU.
Guess that makes it official,PSU is functioning as it should.
I then re connected the mainboard but unplugged the T-con board,result=same 4 blinks and on/off attempts.
So,in my humble opinion it's a toss between mainboard and T-con board..
I removed the T-con board and like a good boy I was going to see if the fuse on the T-con was ok.(learned that from BUDM in my other thread) but again,I can't find a fuse on the T-con(my better halve has been telling me I'm blind for a long time already,lol).
Is there a fuse on every T-con or this one doesn't have one?

[budm]

Re: samsung LN-S4041D

Next to right of the connector, CP1 (Circuit Protection 1), with 'T' printed on top.

[martino]

Re: samsung LN-S4041D

Next to right of the connector, CP1 (Circuit Protection 1), with 'T' printed on top.

Funny,was just looking at that thing thinking"I wonder if...."
Anyway's,that fuse checks out good...

I'm leaning strongly to the verdict that the mainboard kicked the bucket.
Re-installed the T-con,unplugged speakers and push buttons etc and it's still doing the 4 flash etc..

Is there anything I can test/reset on the mainboard?? Or accept the fact it's dead and get a different one??

[budm]

Re: samsung LN-S4041D

I never have luck fixing SAMSUNG main board yet.

[martino]

Re: samsung LN-S4041D

I would love to be able to fix main boards. Got several tv's here that need a main board, ugh.
Curious to know if its software related that makes em defective or if there's actually a component failure happening.

[martino]

Re: samsung LN-S4041D

I tried to reset the eeprom Atmel 24c256 by shorting pin 5 and 6 and then plugging the power cord in,keep the short between pin 5 and 6 for 2 seconds then release the short.
No difference,tv non responsive,it happily continuous its flashing/clicking...
If eeprom is corrupt,did I try to reset it correctly? Can the eeprom be beyond repair?