Samsung T23B350 dead?

[masterbateson]

Hi,
Hoping you guys might be able to help, I bought a Samsung syncmaster off of a well known auction site with stand and remote for the princely sum of £5.00

I was hoping it would be an easy fix and Ideally just a solder up job, but alas no.

The symptoms are that the power LED seems to flash 5 times but set appears to be dead other than that.

No startup, no pic, no sign of a backlight.

The tv/monitor is not tappable as in dry joint, doesnt respond to heat and finally didnt like my efforts swapping the 2 caps I had in my stash that matched/fitted.
I thought the chances of me swapping 2 caps, for ones I just happened to have, was probably going to be slim to no chance, Turns out it was the latter.

Has anyone Resucitated/revived one of these criters?
the PSU has 2 lots of markings/possible ID's one 23A0T_CPN but i think it is prob this BN44-00504A.

There are no visibly blown or bulging caps, no signs of scorching, and presumably because I get the Power led flashing I am guessing its safe to assume I have power (bridge rec not blown) and a quick test after trying showed some residual volts on the main smoothing cap.

Any help would be greatfully received.
p.s.
full model off back is
LT23B350EW/EN
ta
Paul B

[masterbateson]

Re: Samsung T23B350 dead?

Ive just realized! Ive posted wrong PSU pics on wrong thread! oh:

These should be here.



silly boy

[Davi.p]

Re: Samsung T23B350 dead?

The procedure is always tha same, TEST PSU FIRST!
Detached from the rest apart mains plug, use voltmeter on the onboard connector, who usually has values printed on pcb, if there's also a lamp psu on same board, find the diodes that rectifies main trasformer output, then put a dummy load, like 1 or 2 12v bulbs for the 12v->more, a 3ohm 10W RES. on the 5v, it must warm up slowly until hot. if the psu is ok, you must check power voltages on interface board, like linear or sm regulators, then you can try to power up the thing with different combination of keys to find the one that pops up video an service mode, if fails locate if present the settings eeprom then try to reset it with the short on pins 5,6 when plugging mains. if it fails, try to detach lvds ribbon and try to power up to see if led pulses changes... etc etc... eeprom can also be resetted connecting it to a pc with a simple LUDIPIPO interface..

[budm]

Re: Samsung T23B350 dead?

Check the DCV on pin 12 (A5V) of that white connector that goes to the main board to see if it is steady with the board connected to the power supply board, if it is not steady then disconnect the main board and test the Voltage again.
You also need to report the DCV of the rest of the pins, make sure to put down pin name and follow by the DCV reading.
BN44-00504 POWER SUPPLY/LED backlights driver board.

[masterbateson]

Re: Samsung T23B350 dead?

!
then you can try to power up the thing with different combination of keys to find the one that pops up video an service mode, if fails locate if present the settings eeprom then try to reset it with the short on pins 5,6 when plugging mains. if it fails, try to detach lvds ribbon and try to power up to see if led pulses changes... etc etc... eeprom can also be resetted connecting it to a pc with a simple LUDIPIPO interface..

Not sure what you meen as far as Keys go ( i told you i had been out of the game a long time )

This resetting the settings eeprom sounds like a quick thing I can try.

And never heard of a LUDIPIPO interface unno: do you need some kind of software with that?

Thankyou very much guys for your replies, I am going to try all these things, unfortunately I keep not having time to do much with these patients, as I am trying to set up a new Business after losing my job recently, and juggling that with buying/selling a house to down size, so keep finding another day slips buy and I havent been able to tinker.

A packet of biscuits to you both Davi p and Budm !

Forgot to say, think I will be hitting Google to find info on the above, ta again. me.

[masterbateson]

Re: Samsung T23B350 dead?

Well here goes hopefully I havent done a Boob/made an arse of this.

Main board unplugged / plugged in
pin1 12.9v / 5.2v
pin2 12.9v / 5.2v
pin3 12.9v / 5.2v
pin4 12.9v / 5.2v
pin5 0v / 13v
pin 6 5v / 13v
pin 7 5.2v / 13v
pin 8 3.2v / 81mv
pin 9 5.2v / up=down mv 0--180/200mv ish?
pin10 0 / 45mv
pin11 0 / 0-1.5mv
pin12 4.66 / 0-1.5mv
pin13 184 ish mv / 5.2v
pin14 3.3v / 3.5v)

Measured up pin 1 up to 7 across from 7 to 8? and down to 14 is that right like an IC?

well Ive got something at least.

[CapLeaker]

Re: Samsung T23B350 dead?

This is useless unless we have the pin out name to go with it. Your PSU pic isn't that great to zoom into either.

[budm]

Re: Samsung T23B350 dead?

Post #9:
"You also need to report the DCV of the rest of the pins, make sure to put down pin name and follow by the DCV reading."

[CapLeaker]

Re: Samsung T23B350 dead?

Post #9:
"You also need to report the DCV of the rest of the pins, make sure to put down pin name and follow by the DCV reading."

Post #9? This is post #9! You probably meant post #6.

[budm]

Re: Samsung T23B350 dead?

I mean post #4.
I requested to make sure to put down the pin names and the readings.

[masterbateson]

Re: Samsung T23B350 dead?

I think i need to get google'ing to get myself the schematics, for these 2 monitors.

The other thing i need to do is book myself in at the opticians My eyes must have got worse as I am really struggling to be able to read the print on these boards.

Ive always had 20/20 vision so this is a bit of a shock

[budm]

Re: Samsung T23B350 dead?

Main board unplugged / plugged in
B13V (Switched 13V): pin1 12.9v / 5.2v
E-PWM: pin2 12.9v / 5.2v
B13V (Switched 13V): pin3 12.9v / 5.2v
N.C.(NO CONNECTION): pin4 12.9v / 5.2v
Vamp: pin5 0v / 13v
B-ON (Backlighhts ON): pin 6 5v / 13v
Vamp (Switched Vamp around 12~13V)): pin 7 5.2v / 13v
GND: pin 8 3.2v / 81mv
GND: pin 9 5.2v / up=down mv 0--180/200mv ish?
GND: pin10 0 / 45mv
B5V (Switched 5V): pin11 0 / 0-1.5mv
A5V (stby 5V): pin12 4.66 / 0-1.5mv
B5V (Switched 5V): pin13 184 ish mv / 5.2v
P-ON (PS-ON): pin14 3.3v / 3.5v)

You need to retest them again, the readings are not correct at all:
You probably count the pins wrong.

N.C. (no connection): pin4 12.9v / 5.2v Wrong
Vamp (Switched Vamp 12~13V): pin5 0v / 13v
B-ON: pin 6 5v / 13v
Vamp: pin5 0v / 13v
Vamp: pin 7 5.2v / 13v
B5V (Swithched 5V): pin11 0 / 0-1.5mv
A5V (STBY 5V): pin12 4.66 / 0-1.5mv
B5V (Switched 5V): pin13 184 ish mv / 5.2v

You cannot have switched output Voltages or Control signals if the A5V (5Vstby) is 1.5mV when boards are connected together.
How can you have one pin of B5V pin 11 to be1.5mV but another B5V pin 13 is 5.2V?
Same for Vamp:
Vamp: pin5 0v / 13v
Vamp: pin 7 5.2v / 13v
5.2V on the no connection pin 4?

[masterbateson]

Re: Samsung T23B350 dead?

OMG!!!
Its printed on the board and I didnt see it or couldnt read it.
My eyes must be really shot at.

I will do again tonight.

I didnt read it like that, left to right etc

I read the plug like an IC so i thought i started at bottom left as pin1 worked my way up to pin 7 and then went from top right thinking that was pin8 all way down to pin 14.

So no wonder the readings dont make sense.

Oops/doh!

[masterbateson]

Re: Samsung T23B350 dead?

so after a re test voltages are the same plugged in or out (main board)

pin1 13v
2 =3.3v
3=13v
4=115mv
5=13v
6=100 ish mv
7=13v
8=0
9=0
10=0
11=5v
12=100-300mv
13=5v
14=3.3v

So 5v missing off pin12 is my prob presumably?

[CapLeaker]

Re: Samsung T23B350 dead?

Really? You hafta put the pinout names to the pin out number too. other than that this doesn't mean nothing much and it would tell us right away whats going on instead of fiddling around figuring out what pin out number does what.

Sounds like there is something wrong with Pin12 A5V (always on) rail. Unplug the main board and see if it comes up?

[budm]

Re: Samsung T23B350 dead?

so after a re test voltages are the same plugged in or out (main board)

pin1 13v
2 =3.3v
3=13v
4=115mv
5=13v
6=100 ish mv
7=13v
8=0
9=0
10=0
11=5v
12=100-300mv
13=5v
14=3.3v

So 5v missing off pin12 is my prob presumably?

Where are the pin names? Did I just waste my time providing the pin names?

[masterbateson]

Re: Samsung T23B350 dead?

so after a re test voltages are the same plugged in or out (main board)

pin1 =B13v=13v
2 =EPWM=3.3v
3=B13v=13v
4=N/C=115mv
5=Vamp=13v
6=B_on=100 ish mv
7=Vamp=13v
8=GND=0
9=GND=0
10=GND=0
11=B5v=5v
12=A5v=100-300mv
13=B5v=5v
14=P_on=3.3v

So 5v missing off pin12 is my prob presumably?

Hope that is right

[masterbateson]

Re: Samsung T23B350 dead?

Boy you guys are picky!

Whilst I'm on, anyone got a cure for IBS also?

My ring is red raw today.

[CapLeaker]

Re: Samsung T23B350 dead?

It is not being about picky and I don't mind hunting around for stuff if one really has a problem. BUT for something simple problem like this, yeah it does make a difference. If you would help multiple threads a day, this issue becomes annoying real fast. After all this is just a hobby to help here, I suppose I just could ignore this thread too. If you had provided everything the first place, there would be easily 10 posts less in this thread.

Actually there is more problems: The A5V Pin12 off course and Pin6 B_on (back lights) aren't on, while everything else is.
I think the main IC on the main board is toasted. Unplug the main board from the PSU and redo the measurements. With the main board disconnected from the PSU, measure the resistance between A5V Pin12 and GND Pin8 or 9 on the main board. I wonder if that is shorted?
Please upload a clear picture of the main board.

[masterbateson]

Re: Samsung T23B350 dead?

Yes, i get it.
I was having a laugh/tongue in cheek mate.
Just on a bit of a learning/re'learning curve as not been in the back of anything for a while with a meter.
Hopefully I will get half an hour tonight to re test.