Samsung Syncmaster 225BW

[njkev]

Re: Samsung Syncmaster 225BW

******* Samsung Syncmaster 225BW FIX after unsuccessful re-cap ********

Someone gave a Samsung Syncmaster 225BW a couple of weeks ago to work on. I am familiar with this site & saw that lots of other people had issues with this monitor related to caps. This monitor also had 1 second video, and then cut-out with solid blue LED.

The caps & voltages all looked OK, with no evident ripple on any of the rails. I decided to spend the $4.00 or so for the caps since the caps are probably near EOL anyways. The re-cap was NOT successful, but I honestly did not expect it to fix the problem. ( I am an Electronic Engineer btw...and quite familiar with the design of switching power supplies incorporating PWM).

Unfortunately, I do NOT have the schematic for the inverter board, but found & used the data sheet & eval board of the Full Bridge CCFL Controller for reference. I observed the failure mode of controller & noted the voltages. I have made a couple of minor modifications to the circuit to compensate for a (possible) marginal design using thru-hole parts. All of the CCFL turn-on reliably now. I will take a few more measurements, tweak the values, and then finalize the repair with SMT parts this weekend. If anyone has the schematic for the controller board, it would be helpful for me to scrutinize the design further. Note, I think this model uses a few different controllers depending upon board revision.....so this might not be applicable to your unit.
Kev

[macjr]

Re: Samsung Syncmaster 225BW

Is there anyway to get the necessary Caps locally, like at Radio Shack? I don't have much free time and I'm trying to do this fix today while I do. My monitor has been sitting wiht this issue for months because I simply haven't had the opportunity to do it. I scanned the thread, but 460 posts is daunting

[Toasty]

Re: Samsung Syncmaster 225BW

******* Samsung Syncmaster 225BW FIX after unsuccessful re-cap ********
<SNIP>
If anyone has the schematic for the controller board, it would be helpful for me to scrutinize the design further. Note, I think this model uses a few different controllers depending upon board revision.....so this might not be applicable to your unit.
Kev

Need the board number. Photo? Various ones were used.

Toast

[Toasty]

Re: Samsung Syncmaster 225BW

Is there anyway to get the necessary Caps locally, like at Radio Shack? I don't have much free time and I'm trying to do this fix today while I do. My monitor has been sitting wiht this issue for months because I simply haven't had the opportunity to do it. I scanned the thread, but 460 posts is daunting

Radio Shack caps are -not- suitable for these devices. Nor are any from the surplus site market.

You need to become a bit more familiar with the site and read through some of the threads to understand the relationship between low ESR caps and their use in the SMPS of modern electronics. There is (unfortunately) no FAQ that answers this clearly. It's all in here, but spread out quite a bit.

If you want help on fixing your monitor, I strongly suggest you start a new thread. As you noticed, this one's a bit long in the tooth. Make sure to use the make/model in the title.

Toast

[kc8adu]

Re: Samsung Syncmaster 225BW

this one went corrupt after the recap.
i may have blasted it with rf though.
lit off a 300w 2m amp on an indoor 1/4wave on the hvac duct.
no outdoor antenna on the new place yet.
anyone know a button combo to reset to factory specs?
any front buttons lock it up or give the menu shown.

[Toasty]

Re: Samsung Syncmaster 225BW

https://www.badcaps.net/forum/showpo...&postcount=189

[andysbiz]

Re: Samsung Syncmaster 225BW

When powered on, my 225BW makes a hissing/zapping sound in the upper left corner (if facing the back) for a split second and then goes black. Its not actually off, but the light on the power button does go off.

I also smell a faint ozone odor near the sound. Or it could be what it smells like just being electronic.

I see no capacitors with even the slightest bulge. I see no discoloration in either board.

Any idea? Apologies if this has been addressed, I was unable to find it in a search.

[retiredcaps]

Re: Samsung Syncmaster 225BW

I also smell a faint ozone odor near the sound.

Sounds like ccfls arcing? See pics at

http://s807.photobucket.com/albums/y...klight%20lamp/

[andysbiz]

Re: Samsung Syncmaster 225BW

Sounds like ccfls arcing? See pics at

http://s807.photobucket.com/albums/y...klight%20lamp/

I dont have any burnt or shorted wires, but my bulbs do have a dark grey band 1/8 inch wide at either end. Does that mean they're bad and the problem was never the caps?

[kc8adu]

Re: Samsung Syncmaster 225BW

https://www.badcaps.net/forum/showpo...&postcount=189

wiping the eeprom and letting the unit initialise it fixed it.it got corrupted.

[typhonus]

Re: Samsung Syncmaster 225BW

Unfortunately, I do NOT have the schematic for the inverter board,

I posted the Samsung repair manual earlier on page 16 of this thread, second post from the top.
Was the schematic for the inverter board not located in PDF number 12?

Here is the schematic section again. Let me know if it helps.

[raydinya]

Re: Samsung Syncmaster 225BW

First, let me thank everyone posting here, it helped me a big deal. Here is what I did to get my monitor working again. Originally, it failed developing the bad caps problem. So, after reading this thread, I ordered the caps from digi-keys and replaced them. It worked ok for a few months, then it started turning pink or blue, and the panel buttons were not reacting at all, except for the "AUTO" button, which would turn everything black. In other words, the buttons were useless, and most of the time even power button would fail to shut down. I figured the ccfl's were working fine, so there was something wrong on the video board. So, I looked up the board number (mine is BN41-00772C) and ordered a new one from
http://www.e-techalltv.com/direct/in...2186_2279_2287
Paid about $29 including shipping and packaging. Replaced the board and yay, it works like the new one.

[andysbiz]

Re: Samsung Syncmaster 225BW

When powered on, my 225BW makes a hissing/zapping sound in the upper left corner (if facing the back) for a split second and then goes black. Its not actually off, but the light on the power button does go off.

I also smell a faint ozone odor near the sound. Or it could be what it smells like just being electronic.

I see no capacitors with even the slightest bulge. I see no discoloration in either board.

Any idea? Apologies if this has been addressed, I was unable to find it in a search.

Anyone?

[Toasty]

Re: Samsung Syncmaster 225BW

CCFL's arcing to ground. Inverter shuts down when it senses the overload.

Panel has to come apart to get to them. Careful with the ribbon cable leading to the panel. Connectors are not to be forced. A lever type action is usual to clamp them. Do not bend them excessively.

[kc8adu]

Re: Samsung Syncmaster 225BW

ok a follow up.
initialised the eeprom and the unit recovered....for a while.
one chilly morning it powered up red with blank menu.
revisited and DUH!!!! all the 100uf sm caps on the logic board were high esr.
so replace all of them too.the ones near the linear reg were worst.
the big duh is because i have repaired so many samsung industrial units and i should know by now these are always bad.i used 100/25 fc.

[Toasty]

Re: Samsung Syncmaster 225BW

KC - Through hole or SMD type?

[kc8adu]

Re: Samsung Syncmaster 225BW

smd.

[zero10]

Re: Samsung Syncmaster 225BW

Anyone?

I had this same problem, same corner and all. When I opened it up I found the power wires to that end of the CCFL were much darker than the ones to the bottom, or even than the ends that connect to the board. Upon removing the CCFL tubes from the housing and isolating them on a table I was able to get them to light, however they only lit about 1/3 of the way along and the inverter now shut down after 3-5 seconds instead of almost instantly. I was able to look at the sides of the tubes and they have long thin black marks down the sides, it seems that after they arc for a while they become no good.

I am in the process of parting my monitor out since new backlights were ~$35 and I couldn't be positive that I didn't damage the LCD assembly removing it all, so I decided not to throw further money at a monitor that landed in my hands for free.

To fix yours you should just need new backlights and you'll be on your way.

[Toasty]

Re: Samsung Syncmaster 225BW

Along with the FC SMD series, Panasonic's FK and FP series are also available at Mouser & DigiKey.

Here's the individual series sheets from Panasonic's website for those interested.
The one's supplied by M & DK on the product's pages are general specs. to the series'.

.

[mecoos777]

Re: Samsung Syncmaster 225BW

Bravo, Gentlemen! Thanks to your expertise and posts, I just saved myself $200! Did exactly as you said, but only to the two 820 microfarad capacitors since those seemed to be the bulging ones. Bought the other capacitors for later in case those cause trouble later down the line. Thanks all!