Re: Dell 3007wfp No Image
That's what I thought ... I'll add some clear nail polish on it. Make sure the board is ultra clean and re-assemble. It's kind of scary not knowing what exactly caused this. I can't help but think I got lucky that it didn't blow up any parts....
S. Bouchard
Member
Last Activity: 09-17-2013, 01:07 AM
Joined: 08-19-2013
Location: Folsom, CA
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Re: Dell 3007wfp No Image
When I removed the board, I noticed Thermal Paste which had smeared under the board (I didn't notice it when I re-assembled it). It wasn't much but that's the only thing I can see. The paste was Arctic Silver 5 which is not suppose to be electrically conductive but the manufacturer does state it can be slightly capacitive. If it was that, the monitor had been on for about 72 hours so ... what do you think?
Is it safe to re-assemble? Should I look for something else? This happened right in that snuber circuit you described. Coincidence?...Last edited by S. Bouchard; 09-16-2013, 02:11 PM.Leave a comment:
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Re: Dell 3007wfp No Image
In picture #1, you are seeing the post and above it is where the trace was slightly exposed and where the spark / short jumped across and further exposed / damaged that trace. In picture #3, I agree that joint looks bad but if you look at the new picture is looks fine. I think lighting / reflection / angle or something made it look that horrible.
Here is a new picture showing the post and the damaged / exposed trace above it.
What could have caused the current to jump there? What do I need to do to remedy this?...Last edited by S. Bouchard; 09-16-2013, 12:28 PM.Leave a comment:
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Re: Dell 3007wfp No Image
I'll redo the soldering on that post but neither of those visible in that image had been altered by me. That's original solder.
Looks like it current jumped from that post to the trace above it where a slight part of the trace was exposed.
Should I cover that exposed part of the trace above that post? If so what do you recommend I use?
What may have caused this?...Leave a comment:
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Re: Dell 3007wfp No Image
Monitor worked fine for over 48 hours. About 30 minutes ago, while I was using it, a big electric zap (spark) sound occurred. After this sound, the monitor was still operational (image being displayed was all fine) but for obvious reasons, I unplugged it.
I took it apart again, and found the area where the spark / short occurred. It is right in the area of C132, R132 and R133. Something is definitely going on there.
Given my limited understanding of electronics, I have no idea what is causing this. R132, R133 all check out....Last edited by S. Bouchard; 09-16-2013, 01:51 AM.Leave a comment:
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Re: Dell 3007wfp No Image
Monitor has been on for over an hour. So far so good. The back casing is still off but I can't hear the sound anymore.
In terms of recap, I had a surface mount fuse on the controller board blown and I replaced all the caps on the PSU board with the exception of one (the replacement was too tall). I also replaced that ceramic cap but the replacement has different tolerances so I am not sure if that is ok (let me know on that Budm please)...
Otherwise, right now all looks good.
Thanks for the help and this great sit...Leave a comment:
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Re: Dell 3007wfp No Image
I re-assembled the monitor and hooked it up to a PC via DVI and it is working.
In terms of the faint high-pitch noise, at low brightness I can barely hear it (if at all) but at full brightness, I can hear it a bit (with the power supply back in its metal shielding) the noise at high brightness is more like a small buzz.
So what do you think?Leave a comment:
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Re: Dell 3007wfp No Image
I have not re-assembled the monitor yet. This is with just A/C hooked up to the PSU board.
If that new cap is 472Z 1kv vs. 472K 500v and is half the size of the 472K is there any danger on leaving that one in or should I order a 472K 500v? The tolerances are pretty different on those two. -20% to 85% vs. 10% on the K....Last edited by S. Bouchard; 09-10-2013, 07:13 PM.Leave a comment:
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Re: Dell 3007wfp No Image
I replaced that 472K 500v by a 472z 1kv (just to test) and the vibration / noise almost completely went away (without me touching anything). However, if I touch this new cap with the wooden stick, I can then hear the vibration and the noise. Is this vibration of this new cap related to the fact it has different tolerance % over the K part or is this indicative of the source of the vibration being something else?...Leave a comment:
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Re: Dell 3007wfp No Image
I just removed the resistor and it read 74.9K ... I removed the diode and it seems fine as well (450mv one way and Zero the other).
I removed the 2nd resistor (.36 ohm) and it reads .4 ohm but that's the accuracy of my meter (i believe).
I don't have anything to test that capacitor. If not this capacitor, what else, the MOSFET? How do I test that thing? Doesn't the issue have to be near this resistor (75K) which is making that high-pitch noise?...Last edited by S. Bouchard; 09-04-2013, 04:17 PM.Leave a comment:
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Re: Dell 3007wfp No Image
The cap you are referring to is the C132 (472K 500V) right next to R132 (Correct)?
R132 is 75K and its power rating 2 Watt?...Leave a comment:
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Re: Dell 3007wfp No Image
I don't see any Diode connected in parallel underneath but just in case, have a look....Leave a comment:
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Re: Dell 3007wfp No Image
Will check those and let you know the outcome.
Thanks for the help
Leave a comment:
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Re: Dell 3007wfp No Image
When I press (with a wooden stick) on this 75 Kohms resistor, the pitch does change. It doesn't completely stop it from making that faint high pitch sound but the frequency of the sound changes / become significantly dampened (like absorbed by the wood)....Last edited by S. Bouchard; 09-03-2013, 07:28 PM.Leave a comment:
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Re: Dell 3007wfp No Image
Here is a picture of the part of the power supply board where I believe the high pitch noise is coming from.
Could this 102M KX250 X1Y1 capacitor be responsible for it? Should I replace it or could some other part near it be responsible? All other capacitors have been replaced and even re-swapped with no change on this high pitch.
I just need this last bit of feedback to wrap this up. Like I said the monitor now appears to be working but I don't want to put it back together if this faint high pitch noise is likely to result...Leave a comment:
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Re: Dell 3007wfp No Image
The monitor works now but I just need some feedback on this faint high-pitch noise.
Is it normal or not?
Is it that capacitor or maybe something else. What should I look at to isolate / fix this (if it is something of concern)?Leave a comment:
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Re: Dell 3007wfp No Image
Sorry I missed your post for some reason.
Right now the monitor is disassembled. It is doing this faint high pitch sound with only the power board connected and powered....Leave a comment:
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Re: Dell 3007wfp No Image
High Pitch sound could also be coming from the disc capacitor
102M
KX250
X1Y1
Would one of those potentially also emit a high pitch sound? The sound is faint and I am not certain how much I would be able to ear it inside the casing and all but with the Power Board out, I can hear it.Leave a comment:
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Re: Dell 3007wfp No Image
Quick update: The faint whistling sound is coming from either the 330uf 50v or the 470uf 35v ( i think or some part next to them). When I connect power to the board, I can hear the capacitor charging (sound wise)... the sound is slightly louder when it is charging and then it gets quieter but still makes a faint high pitch sound.
So is it one of the capacitor or something else causing it?...Last edited by S. Bouchard; 08-30-2013, 08:42 PM.Leave a comment:
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Re: Dell 3007wfp No Image
Ok. I changed the Capacitors on the PSU. I also replace the surface mount fuse on the controller board.
I connected power to the monitor and it is now going into test mode (which it was not doing anymore). I'll connect it to the PC but I am assuming it is ok.
However, I do hear some slight humming / buzzing coming from the power board... What might be causing this?Leave a comment:
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