DELL 2405fpw

[Mirage00]

Re: DELL 2405fpw

Ok I think I follow. Keeping in mind that I am not an expert, where would I connect the resistor ? Do I connect one end to the dran and the other end to what?????

[budm]

Re: DELL 2405fpw

Please see the picture.

[Mirage00]

Re: DELL 2405fpw

Ok I removed the MOSFET and tested OHMS between drain and source... it stayed on 1. So I guess its not shorted?

[budm]

Re: DELL 2405fpw

OK, it may not be shorted but it does not mean it is OK, it will have to be tested with active tester. I would replace it any way.

[Mirage00]

Re: DELL 2405fpw

Ok no good Installed MOSFET and D19 DIODE and left the T-CON disconnected... Took a voltage reading of the DRAIN and it was 0 again. Both gate and source where 18.8 where they were last time. So I guess the gate logic is bad?

[budm]

Re: DELL 2405fpw

That is too bad, the Gate voltage is not being switching on and off, so the buck converter IC and other components may be damaged.

[Mirage00]

Re: DELL 2405fpw

Yeah. Ill add a separate 5v supply and see if that works.

[budm]

Re: DELL 2405fpw

That may be the easiest thing to do. It will have to be at least 3A.

[Mirage00]

Re: DELL 2405fpw

OK here is my latest update. I replaced the 5v power circuit on the PCB according the link I posted above. The screen actually works now BUT I have white lines through the whole thing. I can see the computer screen through the white lines so somthing is working right. Not sure what to look at now. I attached pics of the modification and the monitor.

[Mirage00]

Re: DELL 2405fpw

Update... it looks like the new power board is output 11v instead of 5v. Would over voltage to the t-con board cause white lines like that?

[budm]

Re: DELL 2405fpw

That will damage the components and circuits on the T-CON, way too much voltage! It has to be 5V. That is one reason I suggested to use a resistor as a load so you can verify the voltage before hooking it up to the T-CON board.

[Mirage00]

Re: DELL 2405fpw

I was afraid of that. Thanks for all your help though. It was an interesting experience.

[Mirage00]

Re: DELL 2405fpw

Good News!! I disconnected the DC-DC converter I installed (since it was putting out 11v) for some reason and connected an old computer SMPS 5v line to the L1 connector to the T-CON board and TA-DA! The monitor worked perfectly After further research I realized I purchased a negative polarity version of the DC-DC converter board.

[budm]

Re: DELL 2405fpw

Great! you did not have it on long enough to kill the board, lucky you.
The main thing is that you have to be able to turn this 5V power supply on and off.

[Mirage00]

Re: DELL 2405fpw

I ordered this one today.

https://cdn.badcaps-static.com/pdfs/...4ea943619a.pdf

[Mirage00]

Re: DELL 2405fpw

Ahh my final post with pictures of the repair and a working monitor. I would like to thank everyone once again for their help!

[budm]

Re: DELL 2405fpw

That's great, thank you for the follow-up and great job.

[jaded788]

Re: DELL 2405fpw

what was your total cost for this repair? you can buy this board for roughly $50 if you can find it.

[Tduong29@hotmail.com]

Re: DELL 2405fpw

Ok no good Installed MOSFET and D19 DIODE and left the T-CON disconnected... Took a voltage reading of the DRAIN and it was 0 again. Both gate and source where 18.8 where they were last time. So I guess the gate logic is bad?

Ok no good Installed MOSFET and D19 DIODE and left the T-CON disconnected... Took a voltage reading of the DRAIN and it was 0 again. Both gate and source where 18.8 where they were last time. So I guess the gate logic is bad?

Hello everyone!
Before I give the solution to this problem please allow me to introduce myself.
My name is Dan, I've join this forum for some short time now, however this is my first post. I wan't thank everyone that blogs to provide their expertise over the internet from just looking at some pictures (amazing) and reading some symptoms, also I want to thank everyone else for posting their problems (broken electronics) because without them, this site would not be possible. Im truly grateful for this forum. It has helped me numerous times when I'm lost.
So I am honored to be able to provide a solution to this problem today.

Here it is,
If your MOSFET shorted out, it most likely will take out your Z-Duode also. If that's the case, replace both. If your MOSFET is dead but open (my situation), your diode should be fine, just replace the MOSFET.

But you're not done yet. The reason that it still doesn't work is because the controller chip (U1 pin 13) on the main board is not getting its input voltage of 1.4v. The reason is because a 10K surface mount resistor (R14) on the back is also burned out leaving the circuit open.

1. Make sure the monitor is in the ON position and that you can see the back light is lit before proceeding.

2. Unplug the power cable from the monitor (while its still on).

3. Take the main board out, unplug everything except the connector from the power supply.

4. With the main board in your hands still hooked up to only the power supply, plug the power cable back to the monitor. It should come back on and the back light lit up.

5. Use an ohm meter to test the voltage from Ground to the resistor R14 on the back of the main board (just under the MOSFET at the corner of the board). One side should read about 2.5V the other side (goes to pin 13 of U1) should be about 1.4v. If you don't get the 1.4V, replace that 10k resistor and that should solve all your problem under $5.

[ucdzombie]

Re: DELL 2405fpw

Ahh my final post with pictures of the repair and a working monitor. I would like to thank everyone once again for their help!

Hello, can you show me how you connected the SMPS to the L1 connector? I'm a complete dummy. I tried to do the same repair but didn't work. So I want to try the SMPS trick.