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My Dell 2007WFP flickers when you turn it on. I disassembled it expecting a blown cap on the logic or daughterboard but all looks good. I looked at the inverter board and unfortunately one of the MOSFETs is fried. There is some brown goo around the top of the PCB. On the back it looks like it arced from one of the solder points across the traces leading to some being connected. I'm thinking my best bet is to watch ebay and watch for an inverter board replacement to pop up, but is it feasible to replace the MOSFET? It says 1J.26061.001 400IR 635001. I guess I would have to clean up the traces as well.
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Nov 23, 2014 00:53
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| # ? Apr 26, 2024 16:33 |
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Nov 23, 2014 00:57
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The "brown goo" looks like solder flux, so it has probably always been there. Can you post a pic of the actual mosfet?
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Nov 23, 2014 02:56
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theperminator posted:The "brown goo" looks like solder flux, so it has probably always been there. 
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Nov 23, 2014 03:55
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This is what the other two look like on the back of the PCB.  The front of the other two don't have that goo under them on the front either. I assumed it was the MOSFET because it looks different on the front and back from the other two.
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Nov 23, 2014 03:58
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Also just to clarify, the monitor turns on, but it just cycles through all the inputs continuously without stopping. There is a faint high pitch whine. The backlight seems to be working fine (which is why I was looking at the logic board originally). I didn't look at the power board since it's not a power issue. I only looked at the inverter board after not seeing any swollen or burst caps or bad traces on the logic/daughter boards. That's when I saw this pretty gnarly looking transformer so I figured it was the most likely problem.
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Nov 23, 2014 04:12
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That big block there is not a mosfet, but I think you have that covered already. If the backlight itself still works, i'd be hesitant to point the finger at it as the culprit. Have you checked that there is nothing wrong with the button to change the input mode?
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Nov 23, 2014 05:41
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Looks like it's a transformer, though I can't seem to find any replacements these guys have a big range http://www.lcdparts.net/Transformer3D.aspx Maybe email them and ask them if they have a compatible part?
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Nov 23, 2014 05:53
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Watermelon Daiquiri posted:That big block there is not a mosfet, but I think you have that covered already. If the backlight itself still works, i'd be hesitant to point the finger at it as the culprit. Have you checked that there is nothing wrong with the button to change the input mode?
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Nov 23, 2014 06:58
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So the controls board looks fine. It routes in to the logic board by a ribbon cable. The logic board then passes off to a daughterboard. When I give the monitor power there is a high pitch whine and some heat coming from the bottom right of the daughterboard (I think it is the cap adjacent to the glue). I was originally looking for a bad 25V 220uF cap, of which there are eight on the daughterboard and none on the logic board. I think I will go ahead with my plan to replace all eight of these caps as I think one of them is bad.
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Nov 23, 2014 08:03
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This guy and a couple others at badcaps have had luck replacing the 272 chip resistor under the strip of glue so I might try that as well. http://www.badcaps.net/forum/showthread.php?t=15984&page=2
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Nov 23, 2014 08:45
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Before replacing any suspect parts why not grab a multimeter and test what you can first (e.g., those caps)?
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Nov 23, 2014 17:13
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booshi posted:Before replacing any suspect parts why not grab a multimeter and test what you can first (e.g., those caps)?
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Nov 23, 2014 23:24
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I got a multimeter, two of the eight 225uF 25V caps tested bad, I replaced them all and now it no longer jumps around the input sources but doesn't seem to detect an input. So it seems it is half fixed. It still makes a electronic whine when supplied with power, when all but the logic daughterboard are powered there is no whine. This leaves five smaller capacitors and the three copper coils wrapped in black plastic - what are these? Labeled 1J.40229.011 LT SJ with 0631 written on reverse. I think they are inductors - they all seem fine. Can they make an electronic whine or would it more likely be the capacitors? cowofwar fucked around with this message at 05:11 on Nov 28, 2014 |
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Nov 28, 2014 04:56
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http://en.wikipedia.org/wiki/Coil_noise Which one is the logic daughterboard?
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Nov 28, 2014 05:21
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Watermelon Daiquiri posted:http://en.wikipedia.org/wiki/Coil_noise What I've been calling a logic daughter board (on the right, since it directly attaches to the logic board on the left) is apparently called a power coverter board (part 5EL2J08001). cowofwar fucked around with this message at 06:03 on Nov 28, 2014 |
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Nov 28, 2014 05:47
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The little 10uF 25v cap seems a bit wonky on the meter and looks a bit weird on the bottom. I'll swap that one and see if the problems persist.
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Nov 28, 2014 06:03
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Well, with my limited understanding of this stuff, it could just be there is a different resonant or switching frequency than the coil whine videos you can find on the internet. It's almost certainly from the wire inductors there vibrating in time with whatever is switching about in that circuit.
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Nov 28, 2014 06:41
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