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Old 09-07-2019, 12:44 AM   #1
caboose1835
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Default Need help with Samsung T220

Hello everyone,

I recently came into the possession of a Samsung T220. It doesn't show any sign of life. I have already replaced all the caps with nichicon ones minus the 450v one. I also noticed I was only getting about 90-100v on the output of the bridge rectifier and replaced that as well.

I still can't figure out what is wrong with it. When I plug it in on a bench, I get voltages everywhere. The fuses are not blown, and I don't see any standby light at all.

Does anyone happen to have any insight with what I might be able to do?
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Old 09-07-2019, 02:05 AM   #2
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Default Re: Need help with Samsung T220

Please upload good clear pictures so we can see what we are dealing with.
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Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956

Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999

Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl

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TV Factory reset codes listing:
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Old 09-07-2019, 02:38 PM   #3
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Default Re: Need help with Samsung T220

Here are the picture of the Power board

Edit: I have changed caps, C301, 302, 112, 116, 113, 108, 119, 118, 107, 114. I have also changed bridge rectifier at D101 near the big capacitor.

The 1000uf caps at C116, C113 were bulging before I changed them all.

Also I have checked the fuses at F301 and F101 for continuity and get 0ohms across them.
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Last edited by caboose1835; 09-07-2019 at 03:05 PM.. Reason: Additional Info
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Old 09-07-2019, 06:11 PM   #4
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Default Re: Need help with Samsung T220

Quote:
I get voltages everywhere
So what you are saying the power supply is working? This does'nt really tell us much. What voltages are you getting on CN2 (pin number and voltage please)

Last edited by R_J; 09-07-2019 at 06:34 PM..
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Old 09-07-2019, 07:09 PM   #5
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Default Re: Need help with Samsung T220

Pin 1 0.045
Pin 2 13.23
Pin 3 GND 0.000
Pin 4 GND 0.000
Pin 5 5.21
Pin 6 5.21
Pin 7 0.043
Pin 8 0.025
Pin 9 3.313
Pin 10 2.23.
Pin 11 0.707
Pin 12 1.813

All voltages readings taken off GND pins with the board powered and plugged into the other board.
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Old 09-07-2019, 07:38 PM   #6
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Default Re: Need help with Samsung T220

It does seem like the power supply is working, Check for 3.3v at CN102 pin 5 and see if you get a change in voltage on pins 2 or 3 when the power button is pressed, then check if that voltage changes on CN2 pin 11 or 12.
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Old 09-08-2019, 04:47 AM   #7
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Default Re: Need help with Samsung T220

CN102 is the DVI connector. Do you mean CN3, the control panel buttons connector?
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Old 09-08-2019, 05:02 AM   #8
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Default Re: Need help with Samsung T220

This test was done with all connectors in place.

Assuming you meant CN3, not CN102 (DVI COnnector) I tested Pin 5 to GND and got 3.070V in the off state, and then 0.157V when I turned on the panel. I also wanted to point out that the transformer changed noises when I turned the panel off or on. It would almost go away, and then slowly get back to max volume.

Next I tested CN2 Pins 11,12
Pin-----Off-----On
11-----3.070-----0.157
12-----1.813-----0.000

I notice that the voltages are different from my last readings to this one. Im guessing that change is because the tubes and buttons were now plugged in?
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Old 09-08-2019, 11:28 AM   #9
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Default Re: Need help with Samsung T220

Yes I ment CN3, Pin 5 is 3,3 volts, that should not drop,
If pressing the power switch causes the 3.3v to drop there is either a short somewhere or the power supply can't supply enough current.

Check the +5v (pins5&6) and pin2 on on CN2 of the power supply, do those voltages drop when you turn on the monitor?

Last edited by R_J; 09-08-2019 at 11:46 AM..
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Old 09-08-2019, 02:10 PM   #10
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Default Re: Need help with Samsung T220

I just got all voltages for every pin on CN2,3 in on and off states

Pin On-----Off
CN2
  1. 0.047-----3.649
  2. 13.37-----13.86
  3. GND-----GND
  4. 0.000-----0.000 (GND)
  5. 5.21-----5.21
  6. 5.21-----5.21
  7. 0.043-----0.165
  8. 0.025-----0.810
  9. 3.313-----3.313
  10. 0.012-----2.198
  11. 0.157-----3.069
  12. 0.000-----1.813

CN3
  1. GND-----GND
  2. 0.000-----1.813
  3. 0.157-----3.070
  4. (-)0.001-----2.198
  5. 3.311-----3.313

Pin 4 on CN3 started off around .1V but then quickly settled around 0.000 to -0.001ish. Same thing with Pin 12 on CN2
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Old 09-08-2019, 02:27 PM   #11
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Default Re: Need help with Samsung T220

So the monitor IS turning on when the power button is pressed correct?
It seems like the monitor has a backlight fault. Do you have 13v on both sides of F301?
Pin 10 should be for the front led and with 2v there, it should be lit. The fack that it changes tells me that the main board its working, but I think you have your readings wrong, the first row is likely OFF, and the second row is ON

Last edited by R_J; 09-08-2019 at 02:55 PM..
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Old 09-08-2019, 02:34 PM   #12
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Default Re: Need help with Samsung T220

Ah shit. Ill need more hands for this. Will report back on voltage on CN3 while holding down the button.

Also the monitor does seem to "turn on" but nothing happens upfront. No LED no image without a backlight, no life at all.
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Old 09-08-2019, 02:47 PM   #13
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Default Re: Need help with Samsung T220

CN3 - While holding down the power switch
1 GND
2 1.814
3 0.157
4 2.196
5 3.313
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Old 09-08-2019, 02:59 PM   #14
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Default Re: Need help with Samsung T220

Check that function/button board, I suspect you have an issue with the led. pin 4 I believe supplies the voltage for the led itself, and with 2v going to it, it should be on.
That said, I believe you have a problem with the backlight circuit and the power supply section and the main baord are working.

Last edited by R_J; 09-08-2019 at 03:02 PM..
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Old 09-08-2019, 03:27 PM   #15
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Default Re: Need help with Samsung T220

never knew an LED could cause the monitor to not work.

Also if I have an issue with the backlight circuit, shouldnt I still be able to get an image on the screen if I shine a light at it?
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Old 09-08-2019, 03:38 PM   #16
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Default Re: Need help with Samsung T220

The led is NOT causing the monitor to not work, but you don't see the led come on so you think the monitor is not turning on, but it is.
By the way, the led on the front does not come on in standby, it comes on when the monitor is on.

Is the monitor connected to a computer? You can try the flashlight test but if there is no source, there will be no video. plus the monitor will likely time out and sleep.

Last edited by R_J; 09-08-2019 at 03:40 PM..
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Old 09-08-2019, 03:43 PM   #17
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Default Re: Need help with Samsung T220

Would this help at all?

http://www.go-gddq.com/upload/2011-0...2010295520.pdf

Thats the pdf for the service manual
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Old 09-08-2019, 03:51 PM   #18
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Default Re: Need help with Samsung T220

Does it have the schematic for the power supply/inverter? I already have a very similar service manual.
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Old 09-09-2019, 02:22 PM   #19
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Default Re: Need help with Samsung T220

Yeah i think its the same manual. Do you know what I should look at to determine the cause of the backlight circuit to not function?

Also, I have plugged it into a computer and shined a light but could not see anything there. Could it possibly be the logic board?
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Old 09-09-2019, 05:36 PM   #20
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Default Re: Need help with Samsung T220

You can force the backlights on by disconnecting CN2 from the logic board and connect a 1k resistor between +5v (pin5or6) and BL_EN (pin 8)
If you don't get the backlight, connect another 1k between +5v and pin 7 or try pin1
This test will make sure the backlights are working and that the logic board is not sending the commands like it should.
You measured .8 volts an pin 8 when the monitor was on and that is likely not enough voltage to turn on the backlights, it needs to be around 4volts

Last edited by R_J; 09-09-2019 at 05:38 PM..
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