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**jetadm123** · 11-19-2012, 06:49 PM

Re: Samsung T220 : no power at all

With monitor unplugged, try checking the main fuse, F101, for continuity. It's the round component right above the ac plug. If that checks ok then measure the DC voltage across the 100uf 450V main cap.

**tibimakai** · 11-19-2012, 08:37 PM

Re: Samsung T220 : no power at all

I would remove all that white glue. I had a 245BW that it was shorting out through that glue, and after removing all of that glue it just fired right up.
I'm not saying that this will fix your issue, but it may prevent future issues.

**SuperDuty** · 11-20-2012, 11:47 AM

Re: Samsung T220 : no power at all

Ok I've made some tests and found a schottky that seems faulty : https://cdn.badcaps-static.com/pdfs/...d01a5d055f.pdf

There are two of those on the middle radiator, this one shows continuity between the Anode 1 and the cathode, while I get resistance on the Anode 2. The other one show even resistance between anode 1 and 2 and the cathode. And when I test all my other shottkys, I get even resistance between the two anodes and the cathode, so I guess it confirms the faulty shottky ?

Sorry for the basic questions, but so far, I've only replaced capacitors and didn't go much further in the understanding of the circuitry.

**mariushm** · 11-20-2012, 01:29 PM

Re: Samsung T220 : no power at all

That chip is 2 diodes in a package

anode - ==>| -(cathode)- |<=== - anode

pin 2 is common to both diodes. Put meter on diode measurement, then probes on 1 and 2. Should show about 0.5-0.75v in one direction, nothing the other way around.

Not sure how reliable the continuity check would be, some meters have quite high voltage pulses uses to test continuity so the diode would conduct.

Repeat with pins 3 and 2

**SuperDuty** · 11-20-2012, 01:35 PM

Re: Samsung T220 : no power at all

When I check the diode measurement, I get nothing on 1 and 2 and 301 ohms on 2 and 3.

I've checked in my spare schottkys, and I have on from the same brand, with identical specs but in a slightly different package : https://cdn.badcaps-static.com/pdfs/...a2641b132c.pdf
Would it work ?

**randtek** · 11-20-2012, 02:02 PM

Re: Samsung T220 : no power at all

That sub should work just fine.

**mariushm** · 11-20-2012, 02:07 PM

Re: Samsung T220 : no power at all

When doing diode measurements, the meter doesn't normally show a resistance, but the forward voltage. For shottky diodes, 0.3-0.5v is proper value, the datasheet you linked to says the forward voltage is 0.75v but at 10A. It's lower at measurement current.
So that 301 might actually be 0.301 v

Being diodes, the meter should report the forward value on one position of the probes, and when you flip the leads around it should show OL or nothing, as there is no connection between the end of the diodes. Diodes block the flow of current on one direction, so a measurement can only be done in one direction.

So 1 and 2 are the pins for the first diode in the package. 1 is anode (+), 2 is cathode (-). Put the black probe on - , red probe on + .. you should get the forward voltage. Flip the probes, and now you shouldn't get anything. And if you measure continuity it shouldn't beep.

Now you do the other diode, but 3 is anode (+) , 2 is cathode (-) so now the black probe goes on 2, red probe on the 3rd pin

See : http://www.youtube.com/watch?v=hRKzZ...eature=related

**SuperDuty** · 11-20-2012, 02:53 PM

Re: Samsung T220 : no power at all

Originally posted by mariushm View Post

When doing diode measurements, the meter doesn't normally show a resistance, but the forward voltage. For shottky diodes, 0.3-0.5v is proper value, the datasheet you linked to says the forward voltage is 0.75v but at 10A. It's lower at measurement current.
So that 301 might actually be 0.301 v

Being diodes, the meter should report the forward value on one position of the probes, and when you flip the leads around it should show OL or nothing, as there is no connection between the end of the diodes. Diodes block the flow of current on one direction, so a measurement can only be done in one direction.

So 1 and 2 are the pins for the first diode in the package. 1 is anode (+), 2 is cathode (-). Put the black probe on - , red probe on + .. you should get the forward voltage. Flip the probes, and now you shouldn't get anything. And if you measure continuity it shouldn't beep.

Now you do the other diode, but 3 is anode (+) , 2 is cathode (-) so now the black probe goes on 2, red probe on the 3rd pin

See : http://www.youtube.com/watch?v=hRKzZ...eature=related

Thanks for the clear explanation

It's exactly what I did and that's all I get, "1." on the screen and a beep sound one side 1-2 and "325" (not 301) on the 2-3. When I use the diode setting, I get a slightly higher number than with the "beep" continuity setting : "345" one the 2-3 terminals, and "0.002" on the 1-2.

The manual of my multimeter is not very clear about what is being measured apart from continuity. I thought the number was the resistance since it's right next to the ohms settings.

BTW, the fuse F101 is blown, can I replace it with a glass fuse from an ATX PSU or even a cms fuse from a motherboard ? I threw away the few dead power boards I had...arg, why did I do that !!!

Also while removing the glue, I've just noticed that the thermistor TH101 was blown as well and the green ceramic was badly cracked with black traces on the blue plastic capacitor next to it, I'm not sure if it happened before I got the screen or when I was testing the board :/ Luckily I found the exact same one in my stash, but I don't want to blow this one too (it's an SCK 053).

**SuperDuty** · 11-20-2012, 04:38 PM

Re: Samsung T220 : no power at all

Well, I've tried two glass fuses, they both blew instantly :/ There must be another problem

**SuperDuty** · 11-20-2012, 10:14 PM

Re: Samsung T220 : no power at all

Ok I've found something else, the diode D106 seem shorted. When I test the + on + and - on - , I get 742 ohms on the diode setting. Then when I tried the + on - and - on +, I get a constantly increasing reading

EDIT : I've tested the diode outside of the circuit, it's fine...now when I test the circuit WITHOUT the diode, I get continuity between the two welds...WTH ! I doubt this is normal, the diode wouldn't make sense if there was constant continuity between two separate welds...
It's certainly not a multilayer pcb, so the problem is certainly external.

**SuperDuty** · 11-21-2012, 12:01 PM

Re: Samsung T220 : no power at all

I've tested the rectifier, I'm getting 546mV between the two middle terminals, where I should get nothing. Might be the one that has shorted in the end and that blows the fuses.

It's the D2SB60 :

I have a few spare rectifiers but not the exact same one, I'm checking the datasheets.

Would the KPB206 work ? The specs look very close to me :

**SuperDuty** · 11-21-2012, 01:10 PM

Re: Samsung T220 : no power at all

Allright, I dared changing the rectifier and...IT WORKS ! Awesome.

The flat panel looks pretty bad though, I will take it apart and carefully clean every layer, water has made strange things in there.

**SuperDuty** · 11-25-2012, 06:13 PM

Re: Samsung T220 : no power at all

Now that it's clean and dry, it's my new main screen ! It's the largest screen I've ever had so I'm pretty happy to say the least !

The scratches on the panel are only visible on a white screen, in video games and movies, it's barely visible.

**psychophat** · 02-15-2013, 03:50 AM

Re: Samsung T220 : no power at all

My initial issue was the power light keeps blinking and the monitor does not display anything and you need to cycle on/off a number of times before it functions normally. Then at one point it died on me.

I have somewhat nearly the same problem with my T220, I have gone and replaced most of the capacitors and re-checked the fuses as done by SuperDuty. The monitor now has power no more blinking red power indicator. It has:

-OSD
-Self-check

But still no display, when you turn on it cycles normally first displays the Samsung logo, black screen, source check, analog, digital, analog, digital then when its like it should now display the desktop screen it just shows a "blank black screen".

The menu works so that means it probably detects in the input but sadly no display.

Kindly advise what else can I do to check or remedy the issue.

**psychophat** · 02-15-2013, 03:54 AM

Re: Samsung T220 : no power at all

Additional: When you press the "Source" button it shows that its trying to detect and it likes it has detected then when it suppose to show the desktop it's still a "blank black screen".

Also the "Automatic" works to reset the settings, you can lock or unlock the menu. But still no display coming from the computer. Am currently using the same computer on an old CRT. This is currently all that I've done so far, kindly advise what else can I do?

**selldoor** · 02-15-2013, 04:16 AM

Re: Samsung T220 : no power at all

Have you tried different cables between PC and T220.
Try with the pc on its lowest resolution and turn dow the brightness
to 30% and see if it makes any difference.

Check that the lvds cable between main board and panel is secure.

Post CLEAR pictures of the fronts and backs of your boards
please post good clear pictures of the whole chassis, and then pictures of each board, front and back (in the same orientation) and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed

https://www.badcaps.net/forum/attach...7&d=1280167246

https://www.badcaps.net/forum/attach...6&d=1280167246

https://www.badcaps.net/forum/attach...4&d=1280167246

**psychophat** · 02-20-2013, 04:35 AM

Re: Samsung T220 : no power at all

Tried every assortment of cable types:
- VGA to VGA
- VGA with DVI adapter to DVI
- DVI to DVI

No go, even if I set the computer resolutions differently it will look like its detects and should show the desktop but it still black.

Okay will do post pictures, just need to find a decent camera. TY will post again.

**selldoor** · 02-20-2013, 06:15 AM

Re: Samsung T220 : no power at all

And the LVDS cable?

**psychophat** · 03-10-2013, 06:04 AM

Re: Samsung T220 : no power at all

LVDS cable is somewhat ok, I think but am already in the process of acquiring one.

Below, self-test.

With logo after power on, there is a 3 rectangle glitch on the logo. I suspect the LVDS I will change that as soon as I can find one.

Board that where the video cable connects to (front).

Board that where the video cable connects to (back).

Power board (front).

Power board (back), some darkening caused by the bloated caps they were the 1000's.

I've already replaced all the caps as I've mentioned on earlier on.

Could it be the inverter or the other board, can you suggest how to test if either of those two? Kindly advise other tests I could do or what to replace. Also am testing the T220 along side my old CRT, I've tried changing resolutions and refresh rates to the lowest accepted. The T220 flickers (like it accepted the changes) as with the CRT when changes have been made. After it flickers blank screen again on the T220, but on the CRT the changes took effect.

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