Dell 2407WFP - No display

[TheBay]

Hi all,

Nice forum!,

I'm Dale from Wales UK, electronics/programming is a hobby of mine and my monitor has broken today!

It's a DELL 2407WFP with no display, buttons work correctly and backlight firing up.

Found fuse F1 open on T-Con board 240M2C4LV2.4

Replaced fuse and just get coloured vertical lines, so something else is wrong with the T-Con board or caused board to go, have a stable +5v at board so not PSU.

Does anyone have this board for sale or know what part has failed, or hints on what I can check.

[selldoor]

Re: Dell 2407WFP - No display

Remove clean and reseat the cables between the main board and tcon and if its separate
between Tcon and panel - hopefully you have not damaged the panel getting it out of the case. What volatge do you get on each side of the Tcon fuse. Any voltage test points on the tcon
Pictures might help us help you

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[TheBay]

Re: Dell 2407WFP - No display

Thanks for the quick reply,

I haven't removed the panel, just carefully removed the ribbon connector and LVDS cable, cleaned both connectors. With the fuse in place I get +5v. I will take a photo shortly, but my only camera is an iphone so will do my best

[selldoor]

Re: Dell 2407WFP - No display

Is that vertical coloured lines on a white screen? A lot of lines or a few and do they change places. Next time its powered up wiggle the cables and see if anything changes.
Another thing to try is gently heating the big genesis chip with a hair dryer and watch to see if the lines move.
As the buttons work does the onscreen menu come on?

[TheBay]

Re: Dell 2407WFP - No display

Cheers for the quick reply again.

Covered in multiple coloured vertical lines, no movement, no OSD, no change if wires wiggled.

Will try some heat on that genesis IC but I don't think it's mainboard related.
Something must have gone to take F1 out on the TCON. I suspect LD1117 but don't know what versions they are, hope the WiseView IC isn't blown , also all caps SMD so no idea of values.

Pic's coming up shortly.

[selldoor]

Re: Dell 2407WFP - No display

No other numbers on the 1117 - perhaps on another line -18? -33? -25?.

They sometimes just blow on a tcon - high temp - they just give up with a slight overload.

[TheBay]

Re: Dell 2407WFP - No display

Only other identifier is C617, but ST don't list this?


Pictures...

[TheBay]

Re: Dell 2407WFP - No display

Checked both of the 1117's out of the board, both check ok!, even swapped them over, In situ I get +3.5v in and 1.25v out on the one, so that's working, but there is no power going in to the other one so need to trace back to see why that's happening. Also the there is a LD33 with +5v in and +5v out.

Got 3.5+ to the other 1117 now, the ground track had blown so repaired it, output on 1117 is showing 0v, lifted the leg and it now gives an output so something on the board is pulling it to ground. Have tried the board without the LCD panel plugged in and it's still the same so at least I think the panel is OK.

[TheBay]

Re: Dell 2407WFP - No display

Now all 1117's are working, I have disconnected LVDS and just run a +3.5 to the TCON and still shows vertical lines.

[selldoor]

Re: Dell 2407WFP - No display

Are you sure there is nothing on the LDOs other than 1117
Cant see resistors on them all so cant all be adjustables when you test you should have black lead on ground and test each leg Middle leg is usually same as the tab. and quote all the results.

On the flat ribbon connector is there a clip that folds flat - it looks upright in the
picture - if you leave it like that when testing it could result in the pic you have.

[TheBay]

Re: Dell 2407WFP - No display

No that was unplugged while testing as I didn't want to damage the LCD.

I have found the fault, I have removed the LCD from it's frame and found this... Any idea what components they are and why have they blown?, is it fixable?.

*Edit* the stick on conductive foam appears to have been stuck on wrong in the factory and was shorting out against this component, it's just labled (CB6) so it's a capacitor but no idea of value...

[selldoor]

Re: Dell 2407WFP - No display

When I said earlier hopefully you have not damaged the panel getting it out of the case this is the sort of damage I meant. At least I think it is damage to the tab bonding, but usually its just the bonding of the ribbon to the panel.

Not sure about finding parts - clean it all up with some isopropyl alcohol and see if there are any markings. -Is there a similar cluster of parts further up the board that you could copy.

[TheBay]

Re: Dell 2407WFP - No display

The whole ribbon is burnt, I swapped caps with ones further up the ribbon and the fault remains, I think both the LCD and TCON board is faulty so I'll break the monitor and sell the inverter, PSU and other parts.

[selldoor]

Re: Dell 2407WFP - No display

Sounds about right - even the panel might sell as bulbs that size are quite expensive or if
you are to continue fixing as a hobby a good one to keep as tester bulbs.
Tcon may be ok the burnt panel probably blew the fuse.

[TheBay]

Re: Dell 2407WFP - No display

Thanks for all your help