Dell 1900FP Monitor - BN44-00041A Inverter

[foxden]

First off, thanks to all posters who have provided me with an incredible source of information.

I have the above monitor, unable to find with searching, which I understand is made by Samsung. Having been successful in repairing another Dell 172FBP (new transistors) I decided to try my hand at this one. Very similar problem, no visible screen just a flashing amber power light and a quick flash of light.

This monitor has an external DC power supply. I took apart the monitor expecting a bad inverter board. It only has one electrolytic capacitor on it, 470uf, I believe and it looks ok, at least not leaking or bulging. I don't have an ESR meter or any real test equipment. The inverter board is almost all surface mount soldering other than this cap. The inverter board is BN44-00041A


Any suggestions as to what might be the common fault with this monitor or inverter board.

Thanks for any help.

[PlainBill]

Re: Dell 1900FP Monitor - BN44-00041A Inverter

First off, thanks to all posters who have provided me with an incredible source of information.

I have the above monitor, unable to find with searching, which I understand is made by Samsung. Having been successful in repairing another Dell 172FBP (new transistors) I decided to try my hand at this one. Very similar problem, no visible screen just a flashing amber power light and a quick flash of light.

This monitor has an external DC power supply. I took apart the monitor expecting a bad inverter board. It only has one electrolytic capacitor on it, 470uf, I believe and it looks ok, at least not leaking or bulging. I don't have an ESR meter or any real test equipment. The inverter board is almost all surface mount soldering other than this cap. The inverter board is BN44-00041A


Any suggestions as to what might be the common fault with this monitor or inverter board.

Thanks for any help.

Well, for starters, the guy holding the screwdriver.

Electronics repair is a logical process. Look at the symptoms, analyze what could be causing those symptoms, test to see if you are right, fix the failing component.

Without some very basic information, you expect us to tell you how to fix it? I've got some basic truths for you. Perhaps you should sit down, this is going to be harsh.

There is no Santa Claus. The Easter Bunny isn't real either. And even the greatest mine here (TopCat) needs a few clues before he can make a diagnosis. The rest of us need even more information.

PlainBill

[foxden]

Re: Dell 1900FP Monitor - BN44-00041A Inverter

Hey, I am sorry. I didn't expect my first post to elicit such a harsh response. I was merely hoping to find out more about this particular monitor and its common failures if any. I guess from my previous problem with the dell I had read so much about its transistors failing that I honed in on the issue quickly.

I had hoped to find some bulging capacitor or leaking one. I guess that would be too obvious.

I have a lot more learning to do, as you pointed out.

Sorry if I offended you because I have a great deal of respect for the knowledge you have.

I am not a technician, but really hate that our society has become such a throw away one. I like to fix things if I can and am willing to read and experiment more.

Thanks for the wake up.

[retiredcaps]

Re: Dell 1900FP Monitor - BN44-00041A Inverter

Assuming the inverter is the same as this one here

http://lcdparts.net/InverterDetail3D...ProductID=2233

what are the two ICs (part number) by the connector and flanked by the two diodes?

If you have DMM or can borrow one, you can test the 4 transistors (what part number are these) next to the inductors as well for shorts.

Have you tried switching the CCFL connections around or remove one at a time to see if one connector is bad?

Post a clear picture after reading the FAQ on posting pictures.

Very similar problem, no visible screen just a flashing amber power light and a quick flash of light.

It only has one electrolytic capacitor on it, 470uf, I believe and it looks ok, at least not leaking or bulging. I don't have an ESR meter or any real test equipment.

[foxden]

Re: Dell 1900FP Monitor - BN44-00041A Inverter

Thanks Retiredcaps,

I already reassembled everything but will likely open it again. The part isn't exactly what you linked to. I am attaching a picture from a vendor's site. I think the transistors are good, tested to see if they were shorted out. I am not sure about disconnecting the ccfls. Do you mean try it with one unplugged?

[retiredcaps]

Re: Dell 1900FP Monitor - BN44-00041A Inverter

A picture from your actual monitor will help because it might show things that people can spot.

Yes, try with one CCFL unplugged and see if one of the them is the culprit.

You *think* the transistors are good? How did you test them? What reading did you get?

Thanks Retiredcaps,

I already reassembled everything but will likely open it again. The part isn't exactly what you linked to. I am attaching a picture from a vendor's site. I think the transistors are good, tested to see if they were shorted out. I am not sure about disconnecting the ccfls. Do you mean try it with one unplugged?

[PlainBill]

Re: Dell 1900FP Monitor - BN44-00041A Inverter

You mentioned a flashing amber LED. This is often a monitor trying to tell you something is wrong. Or it might be a normal 'No Signal' thing. Hook up a video source; if the amber light continues to flash, suspect the power supply or a corrupted user EEPROM.

One picture is worth a thousand words.

PlainBill

[lucky13]

Re: Dell 1900FP Monitor - BN44-00041A Inverter

This monitor has an external DC power supply.

I hope you had tested the external adaptor!

Also, you need to monitor the voltage coming out of the adaptor to see if the "flash" corresponds to a voltage drop. Your problem might be as simple as a defective external dc source.

[retiredcaps]

Re: Dell 1900FP Monitor - BN44-00041A Inverter

Good point, I have 2 monitors that use external adapters. One had a bad cap.

The other works fine, but I only knew that after trying another external adapter to rule it out.

It looks like a few of these 2002 heritage LCD monitors made use of external adapters. I suspect the trend to put them inside the monitors was a cost saving move and to make it easier for users (so they don't lose the adapter or they don't plug in the wrong one).

I hope you had tested the external adaptor!

Also, you need to monitor the voltage coming out of the adaptor to see if the "flash" corresponds to a voltage drop. Your problem might be as simple as a defective external dc source.

[foxden]

Re: Dell 1900FP Monitor - BN44-00041A Inverter

Thanks for the advice, I will keep checking.