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Old 01-12-2011, 01:35 PM   #181
mastertheknife
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Default Re: Samsung SyncMaster 226BW

Quote:
Originally Posted by jetadm123 View Post
You may be dealing with a multi-layered pc board, which has copper traces on different layers of the circuit board. This is used when the designer can't fit all the traces on the outer most layer. That may be why it "appears" that there's just that one resistor tied to VDDA of the OZ964.

What's the part # of U301? It could be the voltage regulator.
Yes, it seems the inverter area is multi-layered.
U301 seems to be a voltage regulator based on temperature. Part number:
KIA
431A
721
The datasheet can be seen here: http://www.alldatasheet.com/datashee...C/KIA431A.html

Thank you,
mastertheknife.
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Old 01-12-2011, 01:54 PM   #182
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Default Re: Samsung SyncMaster 226BW

Here are close pictures of the inverter IC (OZ964GN).
I know the soldering looks terrible, its after reflowing the solder multiple times on everything out of desperation.
Attached Images
File Type: jpg DSC03346_resized.jpg (388.3 KB, 46 views)
File Type: jpg DSC03356_resized.jpg (419.6 KB, 55 views)
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Old 01-14-2011, 12:07 PM   #183
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Default Re: Samsung SyncMaster 226BW

I took out all capacitors to attempt testing them with the limited equipment i have (a simple multimeter).
I discharged each capacitor, then put the multimeter in 2M mode and attached the probes, the capacitors are not shorted and not open, and the resistance went above 2M so i don't think they are leaking either.
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Old 01-14-2011, 12:09 PM   #184
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Default Re: Samsung SyncMaster 226BW

Quote:
Originally Posted by mastertheknife View Post
I took out all capacitors to attempt testing them with the limited equipment i have (a simple multimeter).
I discharged each capacitor, then put the multimeter in 2M mode and attached the probes, the capacitors are not shorted and not open, and the resistance went above 2M so i don't think they are leaking either.
What about ESR?
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Old 01-14-2011, 12:14 PM   #185
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Default Re: Samsung SyncMaster 226BW

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Originally Posted by EGuevarae View Post
What about ESR?
I don't have the equipment to test that unfortunately.

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Old 01-14-2011, 04:32 PM   #186
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Default Re: Samsung SyncMaster 226BW

All caps are nichicon PW except the 330uF one which is a VZ series. According to the internet and the datasheet, the VZ series has higher ESR so i tried to put the old 330uF back but the problem persists.

After replacing caps again and testing other things such as the connections from the IC to the mosfets and from the mosfets to the transformers i am still unable to find anything.
Based on my measurements, i am almost sure the open lamp protection is what shuts off the inverter. According to the datasheet, max voltage for this pin is 2.5V and i measured 2.7V with backlight on, maybe there is a short somewhere, this might also explain the voltage drop when the backlight is being turned on.

Quote:
Originally Posted by retiredcaps View Post
For fun, what about the other way? That is "bad" power/inverter board inside the "other" 226BW?
Same problem, the backlight starts and after 1-2 second its off.

Thank you,
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Old 01-14-2011, 11:47 PM   #187
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Default Re: Samsung SyncMaster 226BW

Is there a way i can bypass the OLP protection somehow temporarily just to be able to rule it out?
Would shorting pin 9 (feedback sense\OLP) with ground do it?

EDIT: No need, fixed the board, details and a picture in the next post

Thank you,
mastertheknife

Last edited by mastertheknife; 01-15-2011 at 12:07 AM..
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Old 01-15-2011, 12:19 AM   #188
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Default Re: Samsung SyncMaster 226BW

It works!!!!

With a better magnifying glass than i have, i noticed there is a solder ontop of a surface mounted capacitor. The multimeter confirmed a short, on the other board the two points measured 4.2Kohms.
After careful removal of the solder ontop with desoldering wick, i measured 4.2Kohms like on the good board.
I then put the board inside, plugged everything and fired up the monitor and it WORKS!!

I can't believe i didn't notice this earlier, must have been my poor vision.
Although i ordered new capacitors and new board just yesterday, i'm still happy it works, i will probably have use for the new capacitors in the "good" 226bw board (the 330uF cap has a plagued top, although for now it works)

The "bad" 226BW belongs to my brother and the "good" 226BW is mine. the "bad" 226BW is now back to my brother.

I have attached a picture of the "shorted" capacitor because of solder ontop of it.

Thanks to everyone attempted to help and to this great site, this forum is like a life saver for old electronics, i will definitely keep visiting
mastertheknife
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File Type: jpg DSC03346_boardfixed.jpg (410.7 KB, 1061 views)

Last edited by mastertheknife; 01-15-2011 at 12:41 AM..
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Old 01-15-2011, 04:47 AM   #189
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Default Re: Samsung SyncMaster 226BW

Congrats. It's always good to see a board that has been troublesome for a long time, finally fixed.
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Old 01-15-2011, 07:41 AM   #190
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Default Re: Samsung SyncMaster 226BW

Yes, good work!!! I commend you on the time and effort you spent trying to fix the problem.
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Old 01-15-2011, 10:28 AM   #191
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Default Re: Samsung SyncMaster 226BW

Thank you both, its amazing how small was the problem and unnoticed for so long!

The monitor was powered on for about 10 hours now continuously with no problems, its like new.

Its unfortunate to see a reputable company like Samsung using low quality capacitors like those CrapXon caps in the 226BW's power supply board.

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Old 01-22-2011, 06:11 AM   #192
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Default Re: Samsung SyncMaster 226BW

Hi all!
I'm happy I found this forum. I have the same problem with bad caps as posted from start.
My caps are:
820uF 25V C646 Vent
330uF 25V C642 Vent
Here in Sweden the largest electronics shop has a 330 uf cap:
https://www.elfa.se/elfa3~se_en/elfa...265|6|394361,;
That shouldnt be any problem, right?
But I can't find any 820cap.
Can any of this work?
https://www.elfa.se/elfa3~se_en/elfa...265|6|392199,;
It does say capacitance tolerance +- 20%.

Thanks for your help and all your good work.
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Old 01-22-2011, 10:25 AM   #193
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Default Re: Samsung SyncMaster 226BW

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As queen says,another one bites the dust ...
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Old 01-22-2011, 12:26 PM   #194
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Default Re: Samsung SyncMaster 226BW

Quote:
Originally Posted by pebe292 View Post
Here in Sweden the largest electronics shop has a 330 uf cap:
I took a quick look and it seems that website does not sell any low ESR caps. It only sells general purpose caps from quality manufacturers like Rubycon and United Chemi-con.

The SMPS requires low ESR caps. Caps from this list are low ESR.

http://www.badcaps.net/forum/showthread.php?t=2280
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Old 01-22-2011, 01:04 PM   #195
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Default Re: Samsung SyncMaster 226BW

Thanks for your reply.
I found the 330 on the badcaps shop but not the 820.
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Old 01-22-2011, 01:21 PM   #196
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Default Re: Samsung SyncMaster 226BW

There are repair kits on ebay:

http://cgi.ebay.com/Samsung-LCD-Moni...item335dfc0b6a

Make sure the caps listed are the ones that correspond to your monitor, since there are two different power supplies used on your monitor. Seller does ship to Sweden. You can email the seller and ask them what series low-esr caps he supplies (this seller's been around a while and should be fine), and if you're confused, you can post his response here and members will provide input.
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Old 01-22-2011, 01:26 PM   #197
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Default Re: Samsung SyncMaster 226BW

Quote:
Originally Posted by pebe292 View Post
Thanks for your reply.
I found the 330 on the badcaps shop but not the 820.
For the 820uF 25V, you can try the Samxon GT 1000uF 25V found here at Badcaps.net

http://www.badcaps.net/store/product...roducts_id=109

The specifications for the Samxon GT and very close to the Panasonic FC series so it is suitable for low ESR applications.

Samxon specs at

http://capsmod.net/PDF/GT.pdf

Panasonic FC specs at

http://industrial.panasonic.com/www-...BA0000CE22.pdf
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Old 01-22-2011, 01:40 PM   #198
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Default Re: Samsung SyncMaster 226BW

Thanks for your reply, both of you.
I think I go for that on Ebay.
Just hope for a quick shipment.
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Old 01-22-2011, 03:32 PM   #199
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Default Re: Samsung SyncMaster 226BW

pebe292:
I bought the repair kit on ebay for my brother's 226BW power board (Rev 0.1), the 330uF cap was nichicon VZ (which seems to be a general purpose cap) and the 680uF and 820uF caps were nichicon PW. the 47uF cap only had "CHNG" on it.
I am now replacing the caps on another 226BW of mine and this time ordering the caps separately from ebay. it might be more expensive than the kit but you end up with more capacitors.
330uF 25V Rubycon ZL caps (10mm dia, 12.5mm height): http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT
820uF 25V Nichicon HD(M) caps (10mm dia, 25mm height, it should fit): http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT
And if you've got a rev 0.1 board, here are 680uF caps:
680uF 25V Nichicon HD(M) caps (10mm dia, 16mm or 20mm height): http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT

mastertheknife

Last edited by mastertheknife; 01-22-2011 at 03:36 PM..
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Old 01-24-2011, 01:08 PM   #200
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Default Re: Samsung SyncMaster 226BW

Hi everyone,

My cheap(works nicely though) capacitance meter from ebay arrived today. It arrived a little too late, because the board is already fixed. But why not test the old CrapXcon caps from the 226BW power supply board? I have compared some of the old capacitors to some new ones.
On the board (rev 0.1) there are: 1x330uF-25V, 2x680uF-25V, 2x820uF-25V, 1x47uF-50V, 1x450V cap.

Seems like the capacitors around the heatsink dried up or something, their capacitance is really low.

330uF (plagued): ~83uF

820uF 1 (plagued): ~137uF
820uF 2 (plagued): ~128uF
820uF New (Nichion HD): ~805uF

680uF 1 (wasn't plagued): ~645uF
680uF 2 (wasn't plagued): ~653uF
680uF New (Nichicon HD): ~730uF (can caps arrive overrated?)

47uF-50V (wasn't plagued): ~47uF

It seems the small 47uF 50V cap was actually fine, and the 3 caps near the power transformer heatsink (330uF and 2x820uF) are the ones that were actually bad. Those were the plagued ones on my board. they probably failed quickly because of the heat nearby from the heatsink. So its probably a safe bet to replace all caps on the board except the 450V one and the 47uF one.

Wish i also had an ESR meter, but those seem too expensive for now.

mastertheknife.

Last edited by mastertheknife; 01-24-2011 at 01:18 PM..
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