Samsung Syncmaster 225BW

[Per Hansson]

Re: Samsung Syncmaster 225BW

I would check the ESR of those surface mount electrolytic capacitors.
Probably after all these years with heat they are bad.

[shodanx]

Re: Samsung Syncmaster 225BW

This 13 years old thread is amazing, it should go in an internet museum.

So I have 5 display setup that consists of one 40" monitor surrounded by 4, ethernet wired samsung 225bw

Picture of my full setup (from last year or so)



Now I had a problem with these display, sometimes they momentarily turn black and come back (and the backlight stays on during this !)

Sometimes the front panel freezes and I have to flip the switch behind to reset it. Sometimes the screen will become 100% red only because the color values have become wrong (press second button from the left 4 times to fix this, if it's not frozen, that will reset all the colour settings by setting the display values to "game" colours)


So I noticed this was become more of a problem with heat so I went and dismantled 3 of them, fixed the busted backlight inverter caps. Also changed some that were not busted. In all cases that did not fix it.

Here I am fixing the caps



So I had the electronics powering the boards out of the case like this and pumping the kind of dynamic colourful scenes that have high change of triggering the black screens.


Lo and behold, I cannot get it to do black screens or even freeze while out of the case !?

I took a measurement of the chip in the middle, 43C in open air

Here is the board close up



Couldn't find anything explicitly bad with it.

So I decided maybe it is the heat that is doing it ?

Then I took my big hairdryer and shot it at the PCB on full blast.

And that triggers the problem in seconds.

When it cools down it doesn't do it.

So I decided to cut a window in the case



Here is the finished product for now, until I can install a fan




I asked for driving my mini fan at low speed so it doesn't make noise

on reddit, but haven't got an answer yet

https://old.reddit.com/r/AskElectron...s_12v/idrmzi9/

I made this video of trying to power this fan with a programmable power supply

If you notice the samsung 225bw has for some unknown reason a 12V barrel jack output ! And I'd like to use that to power the fan at low speed.

[Cap_search]

Re: Samsung Syncmaster 225BW

I opened it today, just for a check, and wanted to measure the big cap 150uF/450V...

Cap measured 119uF. That's why it always seemed not that "bright" enough. A new 180uF/450V is in it now. Monitor now is much better in terms of colour...

[redwire]

Re: Samsung Syncmaster 225BW

If you run these Samsung LCD monitors "into the ground" - keep using them with shot PSU caps and high ripple on the +13V rail, the other capacitors get cooked on the IP board.

I also replace the IP board caps for the +13V_IN to 5V and 3.3V buck regulators. 100uF input and the outputs are usually polymer.
This stops the oddball problems with the digital board which happen due to the power supply board having bad caps.

[TylerCiggy]

Re: Samsung Syncmaster 225BW

Hello there. I guess this is the oldest thread I've been through in my life.

Long story short. If your monitor turn on but doesn't show signal (not even the OSD), just press the Down button and then press the Enter button for 10 seconds, then when "Digital" shows (if still black screen), press the down button again to change preset. It's not a permanent fix, but it may help some people, because I haven't really seen this problem here.

Long Story:
I don't know where to even start, I have this 225bw monitor for over 8 years. I don't even remember where did I buy it and if I bought it dead for repair.

Originally, I came across this thread and I can't remember if Digikey weren't sending internationally or the shipping was too high, so I ended buying some Teapo caps but with no success (I remember non low-esr caps may work but may not last over a year, so it was fine with me). So I got bored about it and went to an authorized samsung repair center which were charging me around 90 dollars (currency at that time, now it would be like 45usd because my country currency is sh1t ) and I bought it for 50, so I was planning to abandon it, but after some time they were calling me saying that I can pay half price and I accepted the deal.

They put some nichicon caps and they didn't replace all the caps as far as I remember. Although I'm not very sure if they did something to the eeprom because my configs doesn't save.

Well, everything was fine until it kinda failed "again" (not same failure). By the way, if my memory doesn't lie to me, it had been already repaired before I bought it, because I didn't found any capxon caps).

The monitor "power up", but couldn't get any signal. The tubes were fine, because I could see the bleeding light with no flickerings and the power button blinking.
Not willing to pay again (and the caps looked fine), I tried things to "fixit without fixing it", powering on and off did the work quite quickly at those times ( I used the back panel switch)

Eventually it worsen up and thinking switching it were going to damage it even further, I began to try pressing buttons to "FWF". Using the enter button to change between analog and digital eventually did the trick.

But after some time, it worsen even more, because I couldn't see even the OSD. So I pressed buttons once more time. So then, after changing between analog/digital I had to press Down button to change the presset, because the "custom" (and somehow default one) was with -81 contrast. Although it didnt work always, it frequently did the trick.

And again, after some time, it worsened even more. By that time, I casually had the gpu connected to the tv as well, and I noticed that if monitor weren't wanting to show signal, if I turned on the tv it will be easier for the monitor to "revive".

Nowadays I have to use this monitor again and was really annoyed of this issues. One thing curious is that if I have the TV on before turning on the signal, sometimes the main monitor was the tv and after reseting/power off-on the PC, the main monitor will be the samsung and if I repeated will be the TV. Of course, when the main monitor was the TV the samsung wasn't wanting to show me signal even when doing the previous explained "tricks".

So today I here again (I guess it's like the third time I'm here) and an idea came to me, maybe I wasn't getting image because a corrupted eeprom was preventing to go out of sleep mode or to make any changes, so after trying the factory reset method I can get signal more easily.

Unfortunatly this doesn't perma fix, but now I don't have to make a ritual for Tlaloc to make my monitor to work.

I'm thinking that it may be between the 47uf cap or the logical board caps (most probably the SMD user Ckshum talked about)

P.D.- I have a Philips TV with buzzing in the power board and the problem was an SMD cap on the logical board.

[Cap_search]

Re: Samsung Syncmaster 225BW

Okay, from what I saw it's fine using higher value (but not much) as these Capxions drift a lot, and C113 can be a 220uF/35V.

Nice monitor!

[Cap_search]

Re: Samsung Syncmaster 225BW

Good evening all,

Sorry to bring it up and perhaps this was already discussed, but here we go:

1. is it mandatory to keep same capacitance values (820uF, 680uF, 330uF, 47uF, etc) when replacing the caps? Or they can be increased by one value higher, e.g. 1000uF instead of 820uF, 470uF instead of 330uF, and so on?

2. there's a "missing" cap in front of heatsink and regulator, I believe it's C113. Someone told in an Youtube video that Samsung wanted to "cut costs" and didn't include that $0.10 capacitor. In case of putting the cap, do you know its value and voltage?

I have the SyncMaster 225BW also to fix its power supply section.

Thank you VERY MUCH!

[budm]

Re: Samsung Syncmaster 225BW

There are pin names for each pin, I can see ON/OFF pin for example but I cannot tell the pin number. Your pictures is not clear enough to see pin numbers and pin names.
I want to see this format: for example
Pin 1 = ON/OFF (this is an example only, I do not know what the pin number for the ON/OFF is) = XX vdc
Pin 2 = GND
Pin 3 = ????? = XXX VDC

[castellscl]

Re: Samsung Syncmaster 225BW

Pin 1 = .094vdc
Pins 2-4 = 0vdc
Pins 5-7 = 13.09vdc,
Pin 8 = 12.98vdc

[budm]

Re: Samsung Syncmaster 225BW

The switching power supply is working otherwise you will not have any DCV at the connector, so no need to probe around the primary side of the circuit.
There are labels for each pin of the connector, what are they?
I expect one of the pin should have 5VDC to run to logic circuit on the main control board.
There is also small green fuse for protection of the backlights inverter circuit, check that fuse and the DCV feeding that fuse.

[castellscl]

Re: Samsung Syncmaster 225BW

Took it back apart, and no obvious connection problems. Yes, the connectors now have the voltage on them: 1 = .094vdc, 2-4 = 0vdc, 5-7 = 13.09vdc, and 8 = 12.98vdc

[castellscl]

Re: Samsung Syncmaster 225BW

Well, after reassembly I get the rapid flashing PWR LED, no back light...
Then after sitting for a bit, the PWR LED turns and stays solid.
After sitting powered on, I start getting some backlight flickering. Still no image though.
I'll tear it down and make sure I got everything together properly.

[budm]

Re: Samsung Syncmaster 225BW

So none of the pin of that small white connector that goes to the main board has NO Voltages at all?

[castellscl]

Re: Samsung Syncmaster 225BW

Ok, yup, silly me. It does have the 167VDC there. I'll try reflowing the solder.

Ok, solder reflow worked, Now I have rapid flashing power LED... and slight clicking sound from "HOT" area on board.

Edit #3: Ok, Held power button for like 10 seconds, and seemed to turn on. Going to throw it back together and see if it works...

[redwire]

Re: Samsung Syncmaster 225BW

Don't go on a goose chase. C105 should have 170 DC VOLTS not AC volts on it.

Just back up and look for cold solder joints/bridges. The standby voltage should be there. Sometimes I've added a new problem when recapping these boards.

[budm]

Re: Samsung Syncmaster 225BW

The C105 I was referring to is the LARGE 105uf450V.

"I have .04vAC across the leads of C105 (Big Cap)."
So why do you try to read AC on the DC cap? It should have about 160~170VDC reading between the two legs of that main filter cap if the 120Vac input is present at the rectifier AC input legs (two inner legs).

[castellscl]

Re: Samsung Syncmaster 225BW

The C105 I was referring to is the LARGE 105uf450V.

[budm]

Re: Samsung Syncmaster 225BW

Ok, I have a Rev. 0.1 board and had the same problem as everyone else. I replaced all 6 Caps with the ones listed in this thread.

Now I have NO POWER at all. No power LED or anything. I've checked TH101 and F101, all good. I have .04vAC across the leads of C105 (Big Cap). I put the old C107 back in to verify and same problem. Not sure of where to test next...

How about good clear pictures of the top and the bottom sides of YOUR board?
BTW, are you talking about the AC Voltage reading on the bog black DC main filter cap C105?

[castellscl]

Re: Samsung Syncmaster 225BW

double post

[castellscl]

Re: Samsung Syncmaster 225BW

Ok, I have a Rev. 0.1 board and had the same problem as everyone else. I replaced all 6 Caps with the ones listed in this thread.

Now I have NO POWER at all. No power LED or anything. I've checked TH101 and F101, all good. I have .04vAC across the leads of C105 (Big Cap). I put the old C107 back in to verify and same problem. Not sure of where to test next...