Leaking capacitor on monitor

[Dinkleburg]

Hello all, this is my first post on this forum so apologies if I get something wrong in advance.

I've had some flickering of brightness levels on a monitor that I was given so I decided to take it apart when it totally died on me, it turns on and shows the desktop for a few seconds then turns off again and it buzzes really loudly, I think it's a capacitor problem but this is my first time trying to fix a monitor like this, so I thought I'd ask someone who knew what they were looking for if this is actually a broken capacitor? Apologies for the poor quality picture

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[Harvey]

The white stuff under the big electrolytic capactitor is not leaked material. More likely, it's hot glue used to hold it down to prevent mechanical shock from cracking the solder joints where it's connected to the circuit board when the set is moved or shaken.

The buzzing sound suggests the problem is in the power supply, and it could be a capacitor or some other component. If the backlight is fluorescent, rather than LED, it could also come from the high voltage inverter circuitry.

If it's that big capacitor, one possible clue would be that the top of the cap (at the right end in your pic) may appear bulged or dome shaped, but I can't tell from the pic. Also, check any other electrolytic caps for the same symptom and for any evidence of leakage around the bottom of those caps. However, electrolytic caps could also be bad without visible symptoms.

You'll need a tech to determine the problem and give you an estimate for the cost of repairing it. If it's something in the power supply, it may be worth fixing. If it's a fluorescent backlight, it could cost more to repair it than to replace it.

Hope that helps. Good luck.

 

[KingFatty]

Feel free to post more pictures so we can take a look around.

The faulty capacitors will typically bulge on their ends (the flat end) or even pop open there, and can be bad without even leaking. There is a design for them to bulge out on the end, like this:

 

[mindless1]

Define totally died, does that mean that even the power indicator shows it is going to sleep or flashing on and off, or does the monitor appear normal except no image?

It could be that you had a bad solder joint that caused flickering and progressively got worse, and that might even account for the buzzing. Use a soldering iron to touch up all joints in the inverter circuit subsection which you can ID by following the traces from the fluorescent tube connectors.

A good, well lit, high resolution top down picture of the PCB might help. Bottom too if it's already out of the monitor.

 

[bryanl]

Flickering brightness is a sign of a backlight problem, either the fluorescent tubes themselves (LED failure is extremely rare) or the power supply for the backlight. Follow the wiring to the backlight to find its power supply. Those Sam Young capacitors in the monitor are not a good brand and should be replaced with something like Panasonic, Nichicon, Nippon Chemicon, or United Chemicon, all available from suppliers like Digikey (cheapest shipping charges). Use parts with appropriate specifications - match capacitance and ESR within 25%, meet or exceed original temperature and voltage. For tight spots also check diameter and length, but those factors are usually not a problem with monitors.

Having a technician diagnose the problem may not be economically feasible, but you want a TV or monitor tech, not a computer tech, who will charge more but likely know less.