Samsung LN_S3251D LED Blinks Once

[Jim8181]

I have a 32" Samsung Model LN-S3251D. It flashes the LED once when I plug it in. That's it.
It appears to have a power board that is not common (at least I can't find much on it). Power board number is BN96-03833A.
Non of the caps "looked" bad, but I went ahead and ordered a cap kit that was for a similar board. I replaced 11 of the 14 caps and nothing changed. I'm picking up the 3 remaining capacitors tomorrow.
2 fuses check good.
Any help will be appreciated.

[tom66]

Re: Samsung LN_S3251D LED Blinks Once

If you do replace the others but do not buy capacitors from RadioShack/Frys etc. I don't think it's necessary. Do you have a digital multimeter? The power supply can be tested.

[Jim8181]

Re: Samsung LN_S3251D LED Blinks Once

The caps came from lcd alternatives. Yes, I have a multimeter.

[tom66]

Re: Samsung LN_S3251D LED Blinks Once

OK, I would suggest you install the power board in the chassis, then measure each of the pins on the connector from the power board to the main board. Red probe on pin to be measured, black on chassis of TV. (All screws in power board should be secured.)

Supply the results like this

#1 - 5.61V
#2 - 3.32V
#3 - 0.02V
#4 - 0.01V

etc.

[Jim8181]

Re: Samsung LN_S3251D LED Blinks Once

From the power board to the main board I have a 5 pin ribbon cable and a 16.
One of those 2?

[tom66]

Re: Samsung LN_S3251D LED Blinks Once

The 16 pin one is the only one we will be interested in for now.

[Jim8181]

Re: Samsung LN_S3251D LED Blinks Once

This connector that says 12v, grd, 5v, 5v, ect? The one with whites and 2 blues?
Whats pin #1? TV plug in? Connector off at main board? Check voltages at the connector?
Hope those questions make sense.

[Jim8181]

Re: Samsung LN_S3251D LED Blinks Once

All of the pins except #1 and #15 are 0.0v.
Pin #1 is 0.1v and pin #15 is 6.04v.

[budm]

Re: Samsung LN_S3251D LED Blinks Once

Please report the reading on CN102 with respect to the label so you/we do not have to figure out which is pin 1.
from the top pin down:
12v =
GND =
5V =
and so on.

[Jim8181]

Re: Samsung LN_S3251D LED Blinks Once

Thanks for the help.
#1 12v = 0.1v
#2 GND = 0.0v
#3 5v = 0.0v
#4 5v = 0.0v
#5 5v = 0.0v
#6 GND = 0.0v
#7 GND = 0.0v
#8 GND = 0.0v
#9 12vs = 0.0v
#10 12vs = 0.0v
#11 12vs = 0.0v
#12 GND = 0.0v
#13 GND = 0.0v
#14 GND = 0.0v
#15 5v = 6.04v
#16 SW = 0.0v

[retiredcaps]

Re: Samsung LN_S3251D LED Blinks Once

Thanks for the help.
#15 5v = 6.04v

Something is wrong with the 5V. About once a week, we get someone who reports incorrect voltages due a weak or dying battery in the multimeter, but there is no such indication of a low battery warning on the lcd.

Recheck pin 15 with a fresh new battery in your multimeter.

[Jim8181]

Re: Samsung LN_S3251D LED Blinks Once

Okay, I changed batteries and tested #15 and it is still 6.04v. I checked it with a second multimeter and got the same results - 6.04v.
And to make sure I'm checking this correctly... I have the tv plugged in, the ribbon cable disconnected from the mainboard and I'm checking at that connector end (the other end is still connected to the power board).

[budm]

Re: Samsung LN_S3251D LED Blinks Once

The strange part is that the other 5v pins shows 0V. I will need to trace out the board to see if the other 5v that shows 0V is switched 5V not standby 5V.
The one that is showing 6.04 may have bad Ref Zener TL431 or bad feedback circuit.

[Jim8181]

Re: Samsung LN_S3251D LED Blinks Once

I don't know if it matters, but when I plug it in I have no way of knowing if the set is on or off.

[tom66]

Re: Samsung LN_S3251D LED Blinks Once

Many Samsung TVs have over-voltage detection from PSU -- such a detection may be stopping it from powering up (causing the brief blink from the LED.)

[Jim8181]

Re: Samsung LN_S3251D LED Blinks Once

Thanks everybody! What do you think my next step should be?

[Jim8181]

Re: Samsung LN_S3251D LED Blinks Once

Just a follow up...
Since I wasn't able to fix the faulty board, I replaced the BN96-03833A (original) power board with a BN96-03057A (substitute). The set works fine now.