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Old 11-16-2014, 07:04 AM   #3
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Default Re: Dell 2407 wfpb no backlight

Originally Posted by budm View Post
You can check the resistance on the right side of the fuse and circuit ground to see if it shows very low Ohm
No short there, it shows 2mega ohm

Originally Posted by budm View Post
also check the Output pin of the 5V reg to see if it shows low Ohms, that will the idea if you have shorted circuit or not.
There is 2.3Kohm between out of 78m05 and gnd

Originally Posted by budm View Post
I am not sure if that fuse feed the input pin (left pin, center pin is GND, right pin is Output) of the 7805 or not.
You can also put your meter in DCA mode to check the current draw.
the 7805 is fed through Q2 an pnp transistor that also seams to be ok, so i belive the 5v circuit is ok, must bee someware else
the Fuse f1 also supplys U1 an 324, and probably a bunch of other components. there are 3 220uF electrolyts on the board, i have ordered some and will replace them
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