Samsung syncmaster t220 Powers on no screen.

[ratboy99]

I've got a Samsung syncmaster t220 that at first would take a long time to turn on. light would slowly blink faster and faster untill it powered on. once it was on i just left it on.
After a recent move from AZ to OR the monitor did its typical flashing power light deal exept this time once the light stopped flashing and was steady i only had a black screen.
So figuring the caps finally died. i pulled it apart and found 2 caps that where nice and fat one was slightly relocated as it was pulling up the trace when it was removed. replaced the 2 caps put it all back together powered it up. the power quickly comes on no flashing light now yet i still have a black screen. placing a flashlight on the screen i can't see anything.

[newbie1]

Re: Samsung syncmaster t220 Powers on no screen.

Hi,
It could be the pico fuse (green fuse beside the BIG capacitor, almost in the middle of the power board) being open. If you have a multimeter, you can measure the resistance of it to confirm whether it is open or not.

p/s: Members here recommend to replace ALL the capacitors except the BIG one if one of them is seen to be bloated, etc. It is recommended to replace them with quality capacitors with low ESR.

[ratboy99]

Re: Samsung syncmaster t220 Powers on no screen.

fuse is good that's one of the few things i checked.

[newbie1]

Re: Samsung syncmaster t220 Powers on no screen.

What brand & series are the replacement capacitors? Are the output voltages measurement reading correctly?

[ratboy99]

Re: Samsung syncmaster t220 Powers on no screen.

my brother is electronic engineer and replaced the 2 bloated caps for me. the brand is OST i think getting him to diagnose the board any farther then that is pretty much not gona happen thats why i've come here.

[newbie1]

Re: Samsung syncmaster t220 Powers on no screen.

If it was me, i would replace ALL the capacitors except the BIG one with quality capacitors with low ESR (like Panasonic FC, FM,FK, etc). I am not too sure whether OST is low ESR that fit to be used in this application.

What is the resistance measurement of the pico fuse that you checked?

Without knowing the output voltages of the power board to the main board it is difficult to assist you even though how much we wanted to. You may also want to recheck the trace which was lifted while replacing the capacitors, you mentioned.

[ratboy99]

Re: Samsung syncmaster t220 Powers on no screen.

fuse was .1 ohm.
Where would you like me to check the voltages at? are you talking about the 12 pin connector that goes to the smaller main board? I'm fluent in using a DMM but i work in the automotive field we never really get into the boards them selfs.

[budm]

Re: Samsung syncmaster t220 Powers on no screen.

There printings on the board close to that white connector on the power supply board which goes to the main board, tell us what they are.
Can you upload better pictures?

[ratboy99]

Re: Samsung syncmaster t220 Powers on no screen.

I don't have the best camera but heres a picture of the connector and pin lableing

[budm]

Re: Samsung syncmaster t220 Powers on no screen.

OK, take the voltage readings on all those pin with the monitor off (in standby mode) and ON mode with running PC connected.
Report the reading of each one of those pins. Pin1 (B-DIM) is the one with Green wire.

[ratboy99]

Re: Samsung syncmaster t220 Powers on no screen.

ok will do. its getting pretty late for me tonight i'll take the readings and report back first thing in the morning thanks for being so helpfull. also would one of the screws or case work as a sufficent ground or should i use one of the grounds in the connector.

[budm]

Re: Samsung syncmaster t220 Powers on no screen.

The mounting screw is fine, or the metal chassis.

[ratboy99]

Re: Samsung syncmaster t220 Powers on no screen.

pluged in/off. / plugged in/on with computer power on
1) 58.1mv~~~~~~~~~~~~1) 4.8v
2) 13.5v~~~~~~~~~~~~~2) 14.63v
3) 0~~~~~~~~~~~~~~~~3) .5mv
4) 0 ~~~~~~~~~~~~~~~~4) .5mv
5) 5.3v~~~~~~~~~~~~~~5) 5.3v
6) 5.3v~~~~~~~~~~~~~~6) 5.3v
7) 53mv~~~~~~~~~~~~~7) 4.51v
8) 32mv~~~~~~~~~~~~~8) 15mv
9) 3.31v~~~~~~~~~~~~~9) 3.3v
10) 161mv~~~~~~~~~~~~10) 2.8v
11) 156.3mv~~~~~~~~~~~11) 3v
12) 0~~~~~~~~~~~~~~~12) 1.8v

[addytzu123]

Re: Samsung syncmaster t220 Powers on no screen.

Hi,

According to the wiring diagram attached, pin 8 is the BL Enable, and with the monitor in ON state you should get approx 3 ~ 3.5V, so the inverter section will start.
I see from the voltages posted that it is missing. Trace back from the pin, into the motherboard and see where the voltage gets lost!

[ratboy99]

Re: Samsung syncmaster t220 Powers on no screen.

I forgot to add before not sure if it makes any difference or not but i did not have the ribbon cable plugged into the screen from the main board as i couldn't get to the pins to test them with it plugged in.

[addytzu123]

Re: Samsung syncmaster t220 Powers on no screen.

If you mean the LVDS ribbon cable from MB to the LCD pannel, it shouldn't make any difference, you still need that BL_ON ~3Volts signal to start the inverter side. This is the job of the MB, so trace pin 8, with a multimeter!

[ratboy99]

Re: Samsung syncmaster t220 Powers on no screen.

what component should that 3v be coming from? i tryed to follow the traces but they go under an IC chip and i can't see where they are supposed to go.

[addytzu123]

Re: Samsung syncmaster t220 Powers on no screen.

Pin 3 of the main chip, SE758MRH it's the BL_Enable pin. It goes into the base of the Q601 transistor via the R601/10 KOhm resistor. What is the voltage at the base of Q601 SMD transistor when all connected and power button pressed?
Q601 should close, and let ~ 3,5 Volts via R600/7.5 KOhm flow into pin 8 of the connector from the motherboard, thus enabeling the Backlight of the monitor.

[ratboy99]

Re: Samsung syncmaster t220 Powers on no screen.

ok so that took my awhile to figure out. i'm not the best with little things. pin 3 on the main chip had 3.2v r601 had 3.2v on one side and .666v on the other. q601 had .666v going into it and MV on the 2 other legs.

[ratboy99]

Re: Samsung syncmaster t220 Powers on no screen.

i also checked the 2 reistors you mentioned i had 9.89k ohms on r601 and 6.9k ohms on r600.