Re: Dell 2007FPb with 4 buck step-down regulators

Thanks sam_sam_sam. I used a similar method and I already know that almost all of this current goes through the 3.3V supply. Current value is about 1,9 A. Just connecting 3.3V power to the VGA board looks the same. On the VGA / DVI Logic board, the voltage of 3.3 V enters two linear stabilizers. You can see them in the photo.
950T65 works fine. Its output is 2,5 V. But 952T43 not works properly. On his output is only 0,4 V ( Should be 1,8 V ).
Static measurement with an ohmmeter showed a short circuit on its output...

Re: Dell 2007FPb with 4 buck step-down regulators

I did some experiments. The measuring environment is shown in the attached figure. Two boards "Buck Convertes" and "VGA / DVI Logic" connected together, powered by a laboratory power supply with current limiting.

1. Current limit set to 1A.
After being turned on, the power supply works in C.C. mode, gives the permissible 1 A from the power supply, the voltage instead of 19V is about 5.5 V. Output voltages are too low. It behaves as if VGA/DVI Logic board has a short circuit.

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Re: Dell 2007FPb with 4 buck step-down regulators



Thank You. Its helpfull. I read this to understand Dead Time Control function....

I have monitor Dell 2007FPb. It was working good. Some day it was shut off and stay dead.
I checked some voltages on the boards. I read this thread:
[url]https://www.badcaps.net/forum/showthread.php?p=335335[/url]
and very usefull budm posts ( thanks buddy, it was great work ... ).
My damage was typical: 3A fuse burned and ZD701 diode was shorten.
So my board is in few points different than other described in citing thread. On my board are 4 buck converter regulators. Apart regulators 3.3V (Q6), 5V (Q14), 12V (Q9), is ther fourth, build on MOSFET Q2. Two TL1451...

Re: New Members - please post your introductions here

hi all. I'm from Poland, and I found this forum when I had trouble with my equipment. I.m not a professional but enjoy fixing some stuff. In my real life I works in informatics