monitor capacitor replacement

jrvzoom
jrvzoom used Ask the Experts™
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Dear Experts,
about a week and a half ago I posted a question on how to fix my monitor, it was determined that some capacitors were kaput, so I accepted the solution, but now when I'm looking at it, I can't seem to tell which one is broken. I've heard that you should either see them bulging or have brownish liquid coming out from the top. I can't see any of this. The link to my last inquire is here http://www.experts-exchange.com/OS/Microsoft_Operating_Systems/Q_26271550.html 
Also here is a picture of the main power board in the monitor.
Thanks, jrvzoom main power board
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Commented:
The photo has many hot spots and many shadowed areas.

Initially, there doesn't appear to be anything 'bulging', but it's really tough to see.

So.
1 - look for a new mainboard - it may save you some solder time.
2 - if you have your heart set on soldering - you could just replace them all.

However,
before doing this...what model monitor?  Did you look for an electical diagram or such...the can be found..sometimes hiddend deep in the web, but I'd start with an electrical diagram before the 'surgery'.  

You are simply attempting the repair for the 'fun' of it, right?

Commented:
I just read the inital post...are you certain its not a failing backlight bulb?  Could be a loose connection there.   Little more expensive to replace.  Also requires soldering...depending on the type you have or can acquire.

Author

Commented:
I am doing it for fun yes, and it's a Dell 1907FPt, I also have attached a new picture taken with a better camera. Also, I am trying to use parts from a Septre X5G-Komodo7 monitor to fix it if at all possible.
IMG-6053.JPG
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Commented:
Where is the backlight bulb exactly?

Commented:
The cap at the bottom right in the photo doesn't look to healthy.

Commented:
http://en.community.dell.com/support-forums/peripherals/f/3529/t/18763169.aspx

@edbedb - that capictor looks ok in the top photo, except the image up top is hard to read in spots.

So jrvzoom, it would be worth inspectoing that capacitor.
The link I found from Dell's site has someone with similar issue who replaced the fuse, so maybe you could get away with a fuse?

The backlight would likely be found in the chassis or near the top/bottom of the glass and it casts its light down/up dependign on how the unit is assembled.  I'll keep looking for better electronic designs.
Commented:
The 19007FPT is not listed here, but possible the other video's may serve some use?
http://www.lcdrepair.us/Installation.html

Commented:
Great second image!


Here is the board:  (if you decide to go that route)
http://www.lcdrepair.us/1707-1907FPt_inverter-power.html


Still scanning through the image, but from the angle, that bottom right corner is in question.  Compared with the first image...I'd say it is not, but the second image brings some doubt.  You could try there and that will be the least expensive start.  De-solder that capacitor, install new and solder it in.  Test.

Author

Commented:
I checked out the website, but that doesn't appear to be the problem, because that person's monitor wouldn't tun on, mine does, but it flickers out. also I took some different angle shots hopefully all these combined should get a good view of it all.
IMG-6055.JPG
IMG-6054.JPG

Author

Commented:
ok, i checked out those websites, but I found one on ebay for less and I think I'll try that capacitor first

Author

Commented:
I've been looking at that one capacitor, the bent one and I can't really find anything wrong with it, but I'll change it out anyway.

Commented:
Good images too.
That small capacitor is hidden, but I suspect it may just be bent...not blown.
With that, if it is bent, it is possible that the connection is bad...and therefore causing some issue.

No problem on finding other sources, I simply found viable links and posted for reference.
The other problem listed I realize wasn't your problem, but sometimes it can lead to other things to consider while your inspecting the part.

Good luck!
Top Expert 2013

Commented:
it is far from sure that the problem  comes from the power supply -  which this board is imo
i suppose there is anotherboard, causing the problem. - some have removable chips -  then you can take it out and reseat it (but ground your self - for ESD problems)

Author

Commented:
Ok, nobus, I took some pics of the only other circuit board besides the one for the lamp and the one for the buttons (however they work) and for the usb connection (not super important) also these are the only two boards with capacitors.  I also put the monitor back together after pushing on all the capacitors just to make sure there wasn't a bad connection and it still blinks out even on the test screen, when you don't plug it into a computer.
IMG-6060.JPG
IMG-6061.JPG
IMG-6062.JPG
Top Expert 2013

Commented:
i never said it were capacitors.
i fear you're in for a replacement board (maybe you find one from a broken same model on e-bay !

Author

Commented:
but which one? are you talking about the main power board? (I'm sorry if I call things by the wrong name, This is my first time repairing a monitor) It seems like all the capacitors look good, but is there any other component that could go wrong and have the same effect on the monitor?
Top Expert 2013

Commented:
you can measure the voltages coming out of the power board (when assembled) - look also for printed info on the board
the capacitor voltage tells you that the voltage line on which they are connected is lower than their voltage.
eg, a cap of 16V will be used on 10-15 V  ..
if you find voltages to be "normal" i would look for the other board )- you can call it the display board

Author

Commented:
Ok, I have looked at your last post nobus, but in between my last post, and your post, I was going to test the back-light by shining a flashlight on it, and so I put it back together without the thin metal protectors on it and it started up fine! I've had it going for like 15 min. now, the only thing it is doing is making a hissing noise at the top right of the screen. Other than that it's a little shadowy, but it works. The only thing is that I didn't really do anything to it.
Top Expert 2013
Commented:
this " hissing noise " is often caused by loose transformer windings
since you did not do anything, it could have been a bad contact
inspect the plugs for corrosion, or burned contacts
signing off for to day - see you tomorrow !

Author

Commented:
ok, thanks nobus, just an update everyone, the screen worked continually until the computer auto turned it off, then it went back to it's blinky self. I think I'll focus my attention on the spot where the hissing came from.

Commented:
@jrvzoom

Look at the link I posted above with the components, this should help with the 'names' of these parts.

http://www.lcdrepair.us/Installation.html

Author

Commented:
I've been working with my soldering iron, and it just died so I won't be able to test out that connection until I get a new one, I'll prob go tom.

Commented:
@jvrzoon,

That stinks.

I was going recommend this earlier:
http://www.google.com/products?hl=en&q=liquid+solder&um=1&ie=UTF-8&ei=HOgvTL7oCOrnnQeHxpj3Aw&sa=X&oi=product_result_group&ct=title&resnum=1&ved=0CDMQrQQwAA

Liquid solder (various companies make it), and I've used it with success.  Not as 'fun' as real soldering, but it does the job for parts that need contacts, nothing with a lot of stress (but you shouldn't have solders where the connection is stressed).

Or...new investments into work tools...always a plus!

Author

Commented:
ok thanks Plantwiz, oh, and a correction, I will not be going tom. because it's Sunday, but I'll go Monday.

Author

Commented:
ok everybody, I re-soldered the connection with the transformer and it's been working fine, thanks
Top Expert 2013

Commented:
nice to see it helped - tx for feedback !

Commented:
Thank you for the update!

Good work!

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