Samsung Syncmaster 2220wm

[RobertoIsRad]

Hi I got a monitor for free from craigslist because it didn't work.
When you connect the monitor and turn it on everything works perfectly...for 2-3 seconds then it shuts off and you have to turn it back on and again only stays on for a few seconds...
So I did a little investigating and the internet lead me to believe that the caps on the power supply were bad. So I replaced everything capacitor wise on the power supply and video board with 1:1 matches of a better brand (nichicon? I went off the good caps FAQ).
Imagine my disappointment when I hooked it back up and found that the problem was the same after all my work.
So I'm just wondering if anyone here has any suggestions on what else I could check or replace.
Thanks in advance!

[retiredcaps]

Re: Samsung Syncmaster 2220wm

So I'm just wondering if anyone here has any suggestions on what else I could check or replace.

"2 second to black" can be

a) bad caps
b) bad inverter transformer
c) bad ccfl or wiring
d) bad inverter sense circuitry

Since you already replaced the caps, focus on b) and c). It is documented starting with posts 13 and 14 at

https://www.badcaps.net/forum/showthread.php?t=10419

PS. Clear focused pictures using the manage attachments help. This is also discussed in post 14 under the misc suggestion.

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

ok, thank you. I'll test some of the things outlined in that post and reply what happens

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

Pictures Incoming

Barcode is on bottom. Pin one is bottom most

1) Bad Capacitors
All replaced and the problem stayed the same. So I have to assume it's something else

2) Shorted Transistors/MOSFETs
D804
1-2= 1 .
1-3= 00.3
2-3= 1 .

D805
1-2= 1 .
1-3= 00.3
2-3= 138.1

D807
1-2= 1 .
1-3= 00.3
2-3= 121.5

3) Open fuse
f801= 00.3
f802= 00.3

4) Bad transformer (truthfully I don't know what I'm doing here and the video was removed...)
T801
Left Side?
1-2= .000
1-3= 1 .
1-4= 1 .
2-3= 1 .
2-4= 1 .
3-4= .000
Right Side? Secondary stuff?
1-2= .000
1-3= .000
1-4= .000
1-5= .000
2-3= .000
2-4= .000
2-5= .000
3-4= .000
3-5= .000
4-5= .000

5) Bad CCFL
I would have to take apart my good working monitor to get an extra ccfl to test with so I'd like to avoid this if at all possible.
Might be a stupid question but can i rig an old case lighting kit for these tests? I think I've got one of them in the closet

6) Bad/cold/poor solder joints
looks OK to me. We'll see after I get some pictures loaded

7) other bad components
**Voltage regulators**
My "U" chips look different from normal VRs. I have u501 and u502 and they are 8 legged chips

**Resistors**
R525 - Should be 1.5Mohms, +/-5% and is 1.481Mohms at 2M setting
R801 - Should be 1Mohms, +/-5% and is .922Mohms at 2M setting
R802 - Should be 1Mohms, +/-5% and is .918Mohms at 2M setting
R803 - Should be 18Kohms, +/-5% and is 17.42Kohms at 20K setting
R805 - Should be 0.18ohms, +/-5% and is 00.4ohms at 200 setting
R806 - Should be 10ohms, +/-5% and is 09.6ohms at 200 setting
R816 - Should be 100ohms, +/-5% and is 92.3ohms at 200 setting
R517 - Should be 33ohms, +/-5% and is 30.9ohms at 200 setting

**Diodes**
For whatever reason I did these ones from the top of the board. Power plug on bottom of board, black starts on left or top
D806
L-R= 1.965
R-L= .605

D803
T-B= .496
B-T= 1.

D802
T-B= 1.
B-T= .520

ZD802
L-R= 1.
R-L= .521

8) Inverter IC sense circuitry/feedback

Is this on the power board, logic board, or the long board still attached/taped to my lcd screen?
I'm going to post pictures tomorrow when the sun comes out and maybe you guys could point it out.

Thank you for your help!

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

Pictures as promised

[jsog]

Re: Samsung Syncmaster 2220wm

On the bottom, the middle lead of those three left of the Q801 label looks very close to touching the pin above it. The cap leg just to the left of them looks bad.

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

I trimmed the lead you thought was touching, and it didn't change anything. I don't know which leg you're talking about though.

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

Ugh, I thought I would take it apart again to have a better look at the board and now the piece of crap won't even power on anymore.... This might be the last nail in this coffin. Any ideas?

[jsog]

Re: Samsung Syncmaster 2220wm

C822, the right-hand connection in the photo doesn't look like the solder wetted to the leg. But it's probably just a little ceramic and isn't significant. Solder on the right pad on the replacement cap right above it, C820, looks questionable, and that one might be significant.

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

I think that it might just have been the light when I took the picturebecause they look good right now.
Also I think I mis-spoke, I changed out all the barrel shaped caps. I never did anything with the disc shaped ones because I don't know how to find the specs for a replacement

[retiredcaps]

Re: Samsung Syncmaster 2220wm

Any ideas?

Okay, let's slow it down first.

1) Does the power LED light come on at all?

2) Are all the internal cables inserted/seated properly?

3) I have attached your picture (excellent btw) where the secondary transformer pins are. With power off and lcd unplugged, put your multimeter on 2000 ohms (if manual) and measure the resistance between the 2 yellow dots. Report measurement. Do the same for the red dots.

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

1) No LED at all, Before it used to turn on as soon as it was plugged in. Then when I pressed the power button I would get the 2 seconds to black. Now it's off if I press the power button or no. I may have popped f802 originally it was reading 00.3 now it's 1 . I'll try to jump it if you think that might be the cause to this most recent problem at least

2) Yes, i've unhooked/hooked everything up a few times and looked at all the cables and they look undamaged.

3)
Yellow Dots
.462

Red Dots
.468

[retiredcaps]

Re: Samsung Syncmaster 2220wm

1) No LED at all.I may have popped f802 originally it was reading 00.3 now it's 1 .

3)
Yellow Dots
.462

Red Dots
.468

If the fuse is reading "1" on the left hand side, it is definitely bad. I'm not a fan of jumpering to bypass a fuse. A fuse exists for a reason.

Let's test the following with power off and lcd unplugged for shorts first before replacing the fuse.

1) Check D801 (bridge rectifier) for shorts. Number the pins 1, 2, 3, and 4. Test 1-2, 1-3, 1-4, 2-3, 2-4, and 3-4 for shorts. This test can be done "in circuit". Any ohms reading under 30 ohms suggests a short. Remove D801 if any reading is under 30 ohms and retest "out of circuit".

2) Check Q804 for shorts. Number the pins 1, 2, and 3. Test 1-2, 1-3, and 2-3 for shorts.

The 2 inverter transformer readings suggest they are good.

If you are going to order a new fuse, order 2 or 3 in case it blows again.

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

D801 and Q804
All combinations yield a "1 ." I assume this is not good? I'm set at 200 on my MM.

[PlainBill]

Re: Samsung Syncmaster 2220wm

D801 and Q804
All combinations yield a "1 ." I assume this is not good? I'm set at 200 on my MM.

If that is the symbol for 'over range', that indicates they are NOT shorted. In other words, good.

PlainBill

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

Great, thank you!

My two monitors you helped me fix last year are still ticking away nicely PlainBill, Thanks again for that!

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

Before I waste my time and potentially risk ruining my nice working 22" samsung monitor...what are the odds that the connections and things would be the same (working monitor is a little newer)?

There's a board on ebay and if I can use my working monitors board to test I think that might be the best route

[retiredcaps]

Re: Samsung Syncmaster 2220wm

Before you buy the board, what caused the fuse to blow? Was it your soldering? Was it your multimeter probes slipping and causing a short?

Since your power mosfet and bridge rectifier are good, it may make sense to replace the fuse now. After you replace the fuse, you can test the power board separate from everything else. If power board has voltage on the secondary outputs (like 5V DC), then the power board is good.

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

ok, I'll see if I can find a fuse tomorrow and put it in.
I believe it blew because I was too lazy to put all the screws back in when I tested it, which must have allowed the board to hang down a little bit and come into contact with the metal cover on the lcd

edit:
I found this fuse http://www.radioshack.com/product/in...ductId=2103767 will this work? Above the fuse on the board it says T4A/125V which I assumed meant 4 amps 125 volt. It might look a little ghetto with a holder for it mounted on, but at least it'll be easy to change!

[RobertoIsRad]

Re: Samsung Syncmaster 2220wm

The fuse was the cause of my power failure, I replaced it and it turns on with 2 secs to black like before.

The two outputs measured 5.1 and 5.09 so then my power board is good? Leaving me with bad ccfls or a bad logic board?