Samsung Syncmaster 245BW

[bermudahonk]

Hi,
I got the new F9222L but still didn't get the unit to work. I also got another monitor that had a burned resistor RB805. This unit is working again. Now I have a working unit so I can check for differences and already done some stuff, but had no luck to find something. I figured out that voltage on pin 11 also is a feedback loop from 24V side. Because the faulty unit does not have 24V the voltage differs on that pin.
I'm still stuck. It seems, that somehow the unit isn't oscilating. I got high voltage ratings on primary winding. But nothing on the secondary. I unfortunately don't possess a oszilloscope to see what is going on. But with my simple voltmeter I see a little voltage on primary winding (TM801S) on the working unit and none on the faulty one. The working unit also makes a low fizzling sound that I would expect. But the faulty one does not make any kind of sounds.
Any hints are apprecitiated.

bermudahonk

[Romb]

May be help anyone. One more bad cap CM802 18nF-630v. It stay only 10pF!!!
Just replace and everything work OK.

[arbreen]

I've got a syncmaster 244t, mostly the same as 245bw, but PVA panel instead of TN and 2006 instead of 2007. No threads on it, but let me know if I should give this its own post.

Symptoms are just like the others, power light blinks but the screen stays dark. So I pulled 'er open, and I've got what are probably a couple of bad caps (pic 1). BUT, the voltages all read correct when the logic board is hooked up: does that mean the power supply isn't the problem? The caps look borderline to me, so I'm hoping more expert eyes can tell me what I've got here.

All fuses are good, nothing looks toasted, and the CCFL inverter uses undamaged-looking Rubycon caps (pic 2) so I'm assuming that's not the problem.

I've included some additional pictures in case that helps with diagnosis. Thanks to anyone that helps out!

[retiredcaps]

Originally Posted by arbreen

So I pulled 'er open, and I've got what are probably a couple of bad caps (pic 1). BUT, the voltages all read correct when the logic board is hooked up: does that mean the power supply isn't the problem? The caps look borderline to me, so I'm hoping more expert eyes can tell me what I've got here.

You definitely have 3 bad caps. These caps are listed at 1000uF 35V so they are probably providing power to the inverter section of the board. I guess "technically", you could consider these caps not part of the power supply.

Replace those caps for sure and retest. Most here will suggest that you replace all the caps on the power/inverter board regardless if they are bloated or not. Caps do not need to be bloated to be bad. They can be out of uF spec, dried out, or have high ESR (ohms).

The Rubycon's look okay.

If you live in the USA, you can follow PlainBill's instructions for ordering Panasonic FM caps. Order Panasonic FC if FM is out of stock or not available.

http://www.badcaps.net/forum/showpos...33&postcount=2

edit: Capxon has a poor reputation for quality. Some members replace Capxon on sight.

[jetadm123]

Originally Posted by arbreen

I've got a syncmaster 244t, mostly the same as 245bw, but PVA panel instead of TN and 2006 instead of 2007. No threads on it, but let me know if I should give this its own post.

Symptoms are just like the others, power light blinks but the screen stays dark. So I pulled 'er open, and I've got what are probably a couple of bad caps (pic 1). BUT, the voltages all read correct when the logic board is hooked up: does that mean the power supply isn't the problem? The caps look borderline to me, so I'm hoping more expert eyes can tell me what I've got here.

All fuses are good, nothing looks toasted, and the CCFL inverter uses undamaged-looking Rubycon caps (pic 2) so I'm assuming that's not the problem.

I've included some additional pictures in case that helps with diagnosis. Thanks to anyone that helps out!

A few things:

1) when you say the voltages are correct, what values are you seeing?

2) can you please post a photo of the entire inverter board?

[arbreen]

Thanks a lot of the prompt reply and all of the extra info! I've found all of the caps in FM or FC from Digi-Key, except for the 100uF 450V. I went with the HC series for that one, as it would fit and handle the same temperatures as the one in there now.

I'll be sure to update when I put it all in there.

[retiredcaps]

Originally Posted by arbreen

I've found all of the caps in FM or FC from Digi-Key, except for the 100uF 450V.

Sorry, forgot to say that the biggest one rarely, but not never, fails. Replacing the biggest one is completely optional, but it certainly does not hurt and can only guarantee the life of the monitor.

And yes, please update us.

[alexanna]

Originally Posted by retiredcaps

Sorry, forgot to say that the biggest one rarely, but not never, fails. Replacing the biggest one is completely optional, but it certainly does not hurt and can only guarantee the life of the monitor.

And yes, please update us.

Are you going to replace the caps on the inverter also?
Al.

[retiredcaps]

Originally Posted by alexanna

Are you going to replace the caps on the inverter also?

They looks like nice colored caps and are rated at 130C.

[arbreen]

Okay then, I haven't hit the purchase button yet so I'll skip the big cap. I figured I'd leave the inverter board alone, since those fancy teal Rubycons show no signs of failure. I took some inverter board pics for jetadm, though hopefully I won't need to do anything with that.

I've only got an old-school analog multimeter to test with, but the 5.4 V, 6.2 V, 13 V, and 24 V rails are all running at as close to nominal values as I could measure.

[alexanna]

Better to have and not need, than to need and not have.
Al.

[MixMasta]

Those caps that are bad, what is the actual voltage going to them?

[jetadm123]

Originally Posted by arbreen

Okay then, I haven't hit the purchase button yet so I'll skip the big cap. I figured I'd leave the inverter board alone, since those fancy teal Rubycons show no signs of failure. I took some inverter board pics for jetadm, though hopefully I won't need to do anything with that.

I've only got an old-school analog multimeter to test with, but the 5.4 V, 6.2 V, 13 V, and 24 V rails are all running at as close to nominal values as I could measure.

Really nice photo of the inverter. It also wouldn't hurt if you were to check the fuse on the inverter board. It's the small white rectangular device at the bottom of the board to the left of the 3 blue caps, marked 3.15A/125V.

[arbreen]

Originally Posted by MixMasta

Those caps that are bad, what is the actual voltage going to them?

Two of them are between gnd and +24v, the other is between gnd and +6.2v. Looking at the tickmarks on the multimeter this time, I've got about 26v and 6.6v actual across those. But each time I turn it on and test voltages, they're slightly different.

and jetadm, I tested the inverter board's fuses earlier and they were good. It's looking like the only thing wrong with the monitor is ten bucks in caps!

[retiredcaps]

Originally Posted by arbreen

Two of them are between gnd and +24v, the other is between gnd and +6.2v. Looking at the tickmarks on the multimeter this time, I've got about 26v and 6.6v actual across those.

6.2 and 6.6V DC are not voltages we normally see in a lcd monitor. For fun, try measuring a fresh AA battery and see if you get 1.5V DC.

If not, try changing the batteries in your multimeter. Over the last several days, multiple people are reporting "strange" readings due to weak or low batteries in their multimeter.

[arbreen]

Maybe the 244t has strange, extra v-outs because it's a PVA panel instead of TN? I've attached a closeup of the specifications printed on the board. It's also labeled in the picture of the traces on the back of the board, along the top edge. It's the only output that works without the logic board connected, so it may be for some always-on feature like the standby LED.

I do need a new multimeter though; it'd be instructive to know whether voltages are really changing or if it's just my tools.

[retiredcaps]

Originally Posted by arbreen

I've attached a closeup of the specifications printed on the board.

I do need a new multimeter though;

Thanks for the picture. Never seen 5.4V and 6.2VDC, but there it is. Sounds like your meter is working fine.

Anyway, change the caps and go from there.

PS. If you are in no rush and are patient, you can get some good multimeter deals on ebay. Just stay from the 830 clones from far east sellers.

[arbreen]

Success!

I replaced everything but the big capacitor, and it works like new! Thanks so much to everyone that helped me out.

I'd show pictures of the finished board, but I put the monitor back together before I thought to take them. Also, my soldering job looks awful. Instead, here's the fixed monitor with its new buddy!

[zx23rr]

Hello, A quick thank you for your great information. I replaced all three resistors RB805, RB806, and RB807. Monitor is now back to life, but I have no red colors.
Any ideas as to the direction to go in?

Sumsung 245BW Dec 07 build date.

Thank you in advance.

[retiredcaps]

Originally Posted by zx23rr

Monitor is now back to life, but I have no red colors.

Factory reset back to defaults?