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Old 02-17-2019, 04:47 PM   #1
Radek
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Default Dell UltraSharp 2007Fp 2nd problem

I have Dell UltraSharp 2007Fp panel Rev A05 built Sept. 2008. I have successfully repaired this monitor couple of years ago by soldering open resistor. See attached photos.
No green or amber light when turned on. Nothing.

There is few threads going, but I am starting a new one as I understand this is the forum etiquette. Pardon me if I am wrong.

I removed all 4 boards and connected them tougheter. I found 19Volts going to USB board. Checked for 3.3Volt 5 Volt and 12Volt. Nothing. Rechecked previously installed resistor, all good there. Discovered 3Amp fuse blown. Soldered in 3Amp glass fuse.
When power was plugged in the 3 A fuse blew.

Since I have no schematic of the board and limited knowledge, I am hoping for some help.

There is a thread here https://www.badcaps.net/forum/showth...07fpb+teardown

With great photos and text. On a text notes it indicates “Monitor will work without USB Board installed”. On another thread I was reading (can not locate it now) that USB board must be connected for monitor to work. So I am confused.

Thank you all.
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Old 02-17-2019, 07:20 PM   #2
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Default Re: Dell UltraSharp 2007Fp 2nd problem

One more measurement. Fuse to Ground short 1.5 Ohm.
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Old 02-18-2019, 02:07 PM   #3
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Default Re: Dell UltraSharp 2007Fp 2nd problem

Well you linked to an excellent thread on the matter.
Please check the diodes discussed there: FD3 and FD4
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Old 02-18-2019, 03:38 PM   #4
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Default Re: Dell UltraSharp 2007Fp 2nd problem

Thanks for the enlightenment. FD3 and FD4 is all I needed, to wake up.
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Old Yesterday, 11:08 PM   #5
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Default Re: Dell UltraSharp 2007Fp 2nd problem

Not a good report.

Replaced pair of diodes FD3 and FD4 with new.

Did not like my large 2.7K resistor so I replaced that one as well.

Plugged it all tougheter and same thing 3A fuse blew.

Tried again with spare 3.5A fuse blew again.

Put back 3A new fuse and left the board by it’s self no other board connected.

Pulled up my adjustable power supply and fed 19V and the Ground to the respective pins
on the board, thinking maybe the short is in other boards.

No. The fuse blew again.

Can any good soul our there help me to find, how to locate this short ?

Thank you
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Old Today, 02:57 PM   #6
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Default Re: Dell UltraSharp 2007Fp 2nd problem

Check Zener diode ZD701, also check the Mosfets.
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Old Today, 03:45 PM   #7
Radek
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Default Re: Dell UltraSharp 2007Fp 2nd problem

Thank you. I am at work now. So I will get to it later.

I located the ZD701 and have to figure out how to test it, if I have to unsolder it or not, I am sure the answer is here somewhere as I was reading about the ZD here.
Mosfets, I think I located 4 of them on this board as I have it with me but will be able to look at this forum better when I get home. Need to figure out how to test them.

Thank again for pointing me in the right direction, appreciate your help very much.
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