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Old 08-11-2009, 06:01 AM   #41
dondrusco
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Default Re: Samsung Syncmaster 225BW

Post a picture of PCB (opposite) part of board.
Feedback control of output voltage to CCFL shuts it down, probably.
Check and solder all parts behind fuses to inverter. Fuses are SMT

Last edited by dondrusco; 08-11-2009 at 06:02 AM.. Reason: add details
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Old 08-11-2009, 05:03 PM   #42
KickToTheJunk
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Default Re: Samsung Syncmaster 225BW

Here's a few shots of the board. One is entire, one is left half other is right half. I'm not an electronics repairman of any sort, I paint and remodel homes for a living. -
Attached Images
File Type: jpg board_entire.JPG (487.4 KB, 488 views)
File Type: jpg lefthalf.JPG (279.1 KB, 307 views)
File Type: jpg righthalf.JPG (295.9 KB, 238 views)
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Old 08-11-2009, 06:03 PM   #43
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Default Re: Samsung Syncmaster 225BW

I turned my brighness down from 100 to 33... Now the moniter is working perfectly.. will try different brightness settings and will see what happens. Also will solder in the other 3 caps, and check other solder joints.
I did notice after hours of trying to get the thing to start, that I could see a "shadow image of my desktop" in the background if the lighting in the room was just right. I think its a backlight problem. I do hear a humming sound at times with the lower brightness setting.

Last edited by bloodpuddle; 08-11-2009 at 06:08 PM..
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Old 08-11-2009, 07:04 PM   #44
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Default Re: Samsung Syncmaster 225BW

Change of plans... Thought my monitor was out of warranty and don't have reciept. Called 1 800 samsung and they said it was still under warranty and sounds like a backlight issue. I soldered in old caps so they won't know I messed with it. They are going to have me ship it, then they will have it back to me in 7-14 days... Thats a long time without a moniter.. Guess I could use my S-video cable to hook to my TV or borrorow my monitor from work nightly.
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Old 08-11-2009, 07:15 PM   #45
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Default Re: Samsung Syncmaster 225BW

My solder joint at F101 (fuse - little reddish plastic round item between the GIANT cap and the power cord/power toggle assembly) looks unharmed and in great shape. Should I (judging my artwork in soldering by the images above) remove it and resolder the fuse back into place or try to locate another?

The digits printed on the board next to the fuse are :
F101 (location)
T3. 15AL
250V
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File Type: jpg fuse.jpg (119.1 KB, 339 views)
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Old 08-11-2009, 07:32 PM   #46
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Default Re: Samsung Syncmaster 225BW

holy crap, mine is under warranty too... figured it was just 1 year like everything else (that I didn't buy an extended warranty on). I'm gonna redo mine and sent it on the all expense paid trip. Now to work on my solder quality... ugh.
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Old 08-11-2009, 09:25 PM   #47
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Default Re: Samsung Syncmaster 225BW

You have to heat up the trace to be soldered to and the component lead with the iron and apply the solder to the trace. Once it's hot enough the solder will flow nicely.

A common mistake is putting the solder on the tip of the iron that burns off all the flux and you get crap joints as a result. Due to oxidation (rust) which the flux removes to make a sound and shiny joint.

That's why during SMT soldering (where you sometimes have to melt the solder on the tip since the leads are so tiny) you have to apply flux manually to the traces to replace that lost flux when it burned off the tip.

Check this link out:

Videos showing soldering basics and even SMT soldering. Pictures are no substitute for seeing good soldering in action.

http://curiousinventor.com/guides
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Last edited by Krankshaft; 08-11-2009 at 09:34 PM..
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Old 08-11-2009, 10:48 PM   #48
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Default Re: Samsung Syncmaster 225BW

I can't belive these monitors have a 3 year warranty! Caught me off guard. I figured after 2.5 years it was expired by now. I could have saved $14 in caps and lots of time messing with the thing. Hind sight is always 20/20. Once i found out, I bought a lotto ticket, as its been a lucky day. I was just about to give up, cut my losses and buy a new one!

Last edited by bloodpuddle; 08-11-2009 at 10:54 PM..
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Old 08-12-2009, 06:12 PM   #49
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Default Re: Samsung Syncmaster 225BW

I just opened mine up and it doesn't look like there is a single good solder joint on the whole board...

Of the three caps mentioned in this thread, two of them have brown discoloration on the tops -the 820uF ones...
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Old 08-13-2009, 01:35 AM   #50
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Default Re: Samsung Syncmaster 225BW

they will have it back to me in 7-14 days ????????
maybe i had one here in uk via Eb@y still in warranty for 2 english pounds and local collection
shiped it back they had 12 weeks then said could not get part !
offered cash part refund 66 english pounds still waiting now been 4 more weeks
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Old 08-14-2009, 12:31 PM   #51
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Question Re: Samsung Syncmaster 225BW

My 225BW show the same "On for a second and then blank with the blue light ON" problem... so open it up, check the board and everything looks good... all caps looks fine...

I decide to order a new board from PartStore (through Amazon)
http://www.amazon.com/gp/product/B00..._ya_oh_product

Just got the new board yesterday but after connecting it ... same problem!

It could be the backlight bulbs?

On the other hand I have a Samsung SyncMaster 216BW in working condition... should I try to test the defective 225BW with the 216BW board?

Thanks for any advice!
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Old 08-14-2009, 01:36 PM   #52
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Default Re: Samsung Syncmaster 225BW

Quote:
Originally Posted by rommelrojas
My 225BW show the same "On for a second and then blank with the blue light ON" problem... so open it up, check the board and everything looks good... all caps looks fine...

I decide to order a new board from PartStore (through Amazon)
http://www.amazon.com/gp/product/B00..._ya_oh_product

Just got the new board yesterday but after connecting it ... same problem!

It could be the backlight bulbs?

On the other hand I have a Samsung SyncMaster 216BW in working condition... should I try to test the defective 225BW with the 216BW board?

Thanks for any advice!
If the connectors are compatible, you could hook the 225BW CCFLs ('backlight bulbs') to the 216BW inverter. If the 216 inverter shuts down after a second, it's the CCFLs in the 225BW panel. I don't think you should hook the data cable from the 216BW electronics to the 225BW panel.

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Old 08-15-2009, 02:42 AM   #53
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Default Re: Samsung Syncmaster 225BW

Quote:
Originally Posted by PlainBill
If the connectors are compatible, you could hook the 225BW CCFLs ('backlight bulbs') to the 216BW inverter. If the 216 inverter shuts down after a second, it's the CCFLs in the 225BW panel. I don't think you should hook the data cable from the 216BW electronics to the 225BW panel.

PlainBill
Agree. Just test the tubes.
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Old 08-16-2009, 03:05 PM   #54
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Default Re: Samsung Syncmaster 225BW

Installed my new caps from DigiKey and my monitor is as good as new!

New soldering iron: $8.99
New solder-sucker: $9.99
New caps: $3.13 (plus $4.95 shipping)

Doing it yourself? Priceless!

Thanks a lot to everyone who has posted on this thread!

Just for reference, here are the parts I ordered:

Code:
Qty    Part#              Mfr Part#                         Desc                    Unit Price
2       565-1800-ND   ELXY250ELL821MK20S     CAP 820UF 25V     0.86
                                                                     ELECT LXY RAD  
3       P10272-ND      EEU-FC1E331L                 CAP 330UF 25V     0.47
                                                                     ELECT FC RADIAL  
Subtotal $3.13
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Old 08-16-2009, 09:31 PM   #55
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Default Re: Samsung Syncmaster 225BW

Quote:
Originally Posted by augustd
Doing it yourself? Priceless!
I agree. Good job
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Old 09-03-2009, 10:31 PM   #56
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Default Re: Samsung Syncmaster 225BW

I just found this forum and wanted to post that I had the same issues with a 225bw. I replaced the 3 caps with new ones and the monitor is working perfectly...I used 2-1000mf 35V and a 330 mf 35V..I am a novice at electronics but did not think this would cause a problem....can anyone agree that the larger caps will not cause any problems?

Thanks!!

Rob
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Old 09-05-2009, 08:55 PM   #57
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Default Re: Samsung Syncmaster 225BW

For everyone who replaced the caps and has it turn on for a second or so then off. Check your polarity of the capacitors the negative should face the black circled half on the PCB if you have a doubt refer to the other caps on the board you did not replace. I accidentally had one cap backwards and had the same issue once I corrected its polarity it works 100%
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Old 09-14-2009, 09:50 AM   #58
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Default Re: Samsung Syncmaster 225BW

I just spent a wonderful afternoon with a Samsung 920BW. Caps ok, power ok, backlight comes on for a second or two and then off - video ok.

On the back of the power/backlight circuit board, I finally was able to read the TINY, TINY p/n on the inverter controller chip. OZ9938. Got a datasheet, comes with reference application circuit. Pin 7 is overvoltage protection, in case a CCFL is dead or not working right. A reference voltage is set there, and when Vsens signal on pin 6 rises above that, the controller shuts off (after about a second). The smd resistors between Vdd and Vss are large value, and the one to Vdd had drifted even higher, so Vref at pin 7 was close to ground, and Vsens was above that in normal operation.

I piggybacked a 1/8w 1meg resistor from Vdd to pin 7, Vref went to 2.5v, monitor now works normally.

Controller IC is made by O2Micro, and they have a series of them for various applications, but I would suspect the pinouts are very similar (it was tough to find that 9938 datasheet!). Worth a look if you have this symptom and cannot find anything else wrong.
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Old 09-14-2009, 11:02 AM   #59
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Default Re: Samsung Syncmaster 225BW

Magistertc
Can you post a link to Datasheet if not can you tell us what pin Vdd is
Thanks in advance
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Old 09-14-2009, 11:04 AM   #60
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Default Re: Samsung Syncmaster 225BW

Quote:
Originally Posted by magistertc
I just spent a wonderful afternoon with a Samsung 920BW. Caps ok, power ok, backlight comes on for a second or two and then off - video ok.

On the back of the power/backlight circuit board, I finally was able to read the TINY, TINY p/n on the inverter controller chip. OZ9938. Got a datasheet, comes with reference application circuit. Pin 7 is overvoltage protection, in case a CCFL is dead or not working right. A reference voltage is set there, and when Vsens signal on pin 6 rises above that, the controller shuts off (after about a second). The smd resistors between Vdd and Vss are large value, and the one to Vdd had drifted even higher, so Vref at pin 7 was close to ground, and Vsens was above that in normal operation.

I piggybacked a 1/8w 1meg resistor from Vdd to pin 7, Vref went to 2.5v, monitor now works normally.

Controller IC is made by O2Micro, and they have a series of them for various applications, but I would suspect the pinouts are very similar (it was tough to find that 9938 datasheet!). Worth a look if you have this symptom and cannot find anything else wrong.
Good information. I usually assume a fault in the driver / transformer / ccfl area is causing a shutdown. Checking the set point would be a good first step.

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