Samsung SyncMaster 2220wm

[el3ctroded]

Flash on, goes dim, then off.

I found a small non-electrolytic cap at the output of the secondary on the transformer in the inverter circuit that is bad, but I'm not sure how to read those... One says 12J 3kv. I know 3kv is 3000V, but is 12J 12pF or what?

The other one says 31J 3kv.

And are the caps that are always on the transformer's secondary in inverter circuits usually ceramic caps?

Thanks!

[jetadm123]

Re: Samsung SyncMaster 2220wm

12J is 12pf where "J" is +/- 5% tolerance
31J is 31pf "

[el3ctroded]

Re: Samsung SyncMaster 2220wm

Ok. Digikey doesn't have 31pF, but they do 33pF. I'm gonna go with that unless you suggest otherwise.

[el3ctroded]

Re: Samsung SyncMaster 2220wm

Got in the caps. The ones I ordered are 6kV, but that shouldn't matter. Put them in and the screen still blinks to black.

Hooked up 4 known good CCFLs and same result.

The secondaries on the transformers measure 472 and 468
I have also replaced the electrolytic caps.
I have re-soldered the joints on the transformers and numerous others.

Still 2s to black

I doubt my new 12pF 6kV and 33pF 6kV caps would be the issue... But maybe the transformer or the IC driving the transformer was damaged due to the old bad ceramic cap shorting internally?

I am getting more and more screens that have this problem and no apparent reason...

[retiredcaps]

Re: Samsung SyncMaster 2220wm

Hooked up 4 known good CCFLs and same result.

Please describe in detail how you tested the above. I'm not doubting your results, but some others who have written the above are doing it a bit differently than I envision.

The way I test ccfl is described at

https://www.badcaps.net/forum/showpo...1&postcount=14

[el3ctroded]

Re: Samsung SyncMaster 2220wm

I have a known good but broken LCD screen I keep around for testing. It has 4 good CCFLs in it.

I attached the samsung power board to the 4 CCFLs in my broken panel. It still does 2s. to black.

I also have done your method, same result no matter which CCFL is swapped.

I did notice this time that 2 of the CCFL connectors failed to light up the spare ccfl..... One is being fed by one transformer, one fed by the other transformer. Odd.

[el3ctroded]

Re: Samsung SyncMaster 2220wm

Any ideas? It has 4 ccfls, one transformer per 2 ccfls. And one ccfl on each transformer doesn't light at all. Both ccfls are known good.

I'm really at a loss to explain how that could happen.

[alexanna]

Re: Samsung SyncMaster 2220wm

Any ideas? It has 4 ccfls, one transformer per 2 ccfls. And one ccfl on each transformer doesn't light at all. Both ccfls are known good.

I'm really at a loss to explain how that could happen.

I have some ideas, but it is going to be a little bit for me to put together my thoughts!
I have some questions,
On a lot of monitors that use one transformer, it’s required that TWO CCFLs be installed to properly complete the circuit. Is that how you tested?
Have you ever, or would you feel comfortable looking at the CCFL return voltages?
And does your DMM have either a min/max record feature, or a bar graph?
A really good focused picture of the inverter top and bottom would really help.

[Rtech]

Re: Samsung SyncMaster 2220wm

The CCFLs that do light....do they light FULLY ???

[pedro]

Re: Samsung SyncMaster 2220wm

Any ideas? It has 4 ccfls, one transformer per 2 ccfls. And one ccfl on each transformer doesn't light at all. Both ccfls are known good.

I'm really at a loss to explain how that could happen.

Describe the connections from each transformer to the CCFL pair. Are the tubes in series on one two-wire connector?? Is there a three-wire connector or two two-wire connectors (per transformer)?

[el3ctroded]

Re: Samsung SyncMaster 2220wm

Sorry for taking so long to get back to you.

Alexanna: Yes, I had all CCFLs connected at all times during the test. I was just swapping out one for another. I wouldn't mind looking at the return voltages. My meter doesn't have min/max record feature, but I have a 200MHz scope...

Rtech: Do they light fully? Do you mean the entire expanse of the tube lights up? I'll double-check.

Pedro: They are not in series, and I'm not sure what you mean by "one two wire connector". The transformer has a single output winding, 2 pins. One pin goes to 1 ccfl, the other pin goes to the other ccfl. the returns each go into separate smt circuitry. And that is repeated for the other 2 CCFLs. See pics.

[alexanna]

Re: Samsung SyncMaster 2220wm

Sorry for taking so long to get back to you.

Alexanna: Yes, I had all CCFLs connected at all times during the test. I was just swapping out one for another. I wouldn't mind looking at the return voltages. My meter doesn't have min/max record feature, but I have a 200MHz scope...

The fact that you had all 4 CCFLs installed when you did your testing changes my thinking, checking return voltages is the not way to go with your monitor.
I really wish I understood this circuit better.
I seriously doubt you have 2 bad inverter transformers, I am wondering if you may have a supply voltage problem, or such high resistance some ware in the circuit that the inverter shuts down before its able to overcome it.
The fact that you have a scope may be helpful, but I haven't had the opportunity to use one.
One thing that really gets my attention is the soldering of the inverter transformers, have you tried removing them completely from the board and cleaning and the re soldering?

[el3ctroded]

Re: Samsung SyncMaster 2220wm

I just tried a new test... I hooked the screen from this samsung monitor up to an inverter that is known to be good. It lit up the screen and stayed on, so I now know 100% that the screen and CCFLs are Ok and the problem is with the inverter circuit.

[lcdman]

Re: Samsung SyncMaster 2220wm

Hello,

I recently rebuilt a monitor like yours. I have the service manual for it. But this site won't accept my pdf? Maybe because I don't use Acrobat Reader? It fits within the file size requirements! If interested pm me and I'll send to you directly.

Have A Great Night

Lcdman

[FIXITNOW]

Re: Samsung SyncMaster 2220wm

you could stick the pdf in to a zip file and upload then it would be here for all whenever needed

[el3ctroded]

Re: Samsung SyncMaster 2220wm

Hello,

I recently rebuilt a monitor like yours. I have the service manual for it. But this site won't accept my pdf? Maybe because I don't use Acrobat Reader? It fits within the file size requirements! If interested pm me and I'll send to you directly.

Have A Great Night

Lcdman

You've got a PM... Thanks. Once you send it, I'll try to attach it to the thread.

[alexanna]

Re: Samsung SyncMaster 2220wm

I just tried a new test... I hooked the screen from this samsung monitor up to an inverter that is known to be good. It lit up the screen and stayed on, so I now know 100% that the screen and CCFLs are Ok and the problem is with the inverter circuit.

Thinking about your monitor, I have some more questions.
Was the soldering on the inverter transformers OK?
Are two of the CCFL connectors still failing to light CCFLs?
Next question are any of the small diodes I have circled tied to the return side of the CCFL connectors?
If so you may want to check and see if any of them are open. Or check with diode function see if they are working correctly.

[el3ctroded]

Re: Samsung SyncMaster 2220wm

Here's the PDF. The only way I could upload it was using a 2-part RAR file. (Rar is another type of zip). Download both parts. Then to open it and extract the PDF file, get 7zip from here. 7zip will open the file and you can extract the pdf.

To open the file, simply tell 7zip to open the part1 file; it will automatically find the part 2 so long as they are both in the same directory.

[el3ctroded]

Re: Samsung SyncMaster 2220wm

Thinking about your monitor, I have some more questions.
Was the soldering on the inverter transformers OK?
Are two of the CCFL connectors still failing to light CCFLs?
Next question are any of the small diodes I have circled tied to the return side of the CCFL connectors?
If so you may want to check and see if any of them are open. Or check with diode function see if they are working correctly.

Soldering redone, no effect.
Yes
yes, but I'm gonna have to take them off the board to test cause circuitry is interfering. None test as open, but I'm getting irregular results.

[el3ctroded]

Re: Samsung SyncMaster 2220wm

Gave up on the PSU as I found a brand new one on ebay cheap. Screen now works.