Introduction: Repair Your Electronics by Replacing Blown Capacitors
Checking for blown capacitors in your malfunctioning electronics is fast and easy if know what you're looking for. Replacing one part at a couple dollars a piece is much cheaper than replacing an entire monitor for hundreds of dollars! Monitors, digital converters, and other video- related electronics commonly have power issues that are caused by faulty (read: low quality production) capacitors. Common symptoms include:
- Unit won't turn on
- Unit won't return from standby
- Unit turns on and off intermittently
- Screen flickering or distorted
- Lines across the screen
If you're experiencing any of these, it's worth taking several minutes to check your circuit board capacitors.
Step 1: Tools Needed
Checking the capacitor just requires your eyeballs but replacing them requires a few tools:
- Screwdriver, hex wrench, or whatever's needed to open the case
- Soldering iron
- Replacement capacitors (you will find the values for this in the following steps)
Also optional but helpful is soldering wick, which is available for fairly cheap at Radio Shack.
In this example I'm repairing a digital TV converter box that will power on, but does not activate from standby.
Step 2: Open the Case
Most important: power off and unplug your unit!
Using your screwdriver or other tools, open up the electronics case so that you have easy access to the circuit board. If you're having trouble, look up the manual online to find out where the various screws and tabs are to open the case.
Bring it up the light so you can see the electrolytic capacitors easily.
Step 3: What a Blown Capacitor Looks Like
A busted capacitor can be obviously broken (leaking brownish fluid, corroded, or with the leads severed), but sometimes it's subtle. The top of a blown capacitor will be slightly bent outwards in a convex shape, rather than flat or slightly indented inwards like a working capacitor. See the photos above for examples.
Think of it like a vacuum-sealed glass bottle. When the seal is intact, the bottle cap is flat, and when you break the seal, the bottle cap pops up. That subtle "popping-up" is exactly what you're looking for.
Step 4: Remove the Old Capacitor
Make a note of the polarity of the old capacitor, and mark the exact values you'll need for the replacement: capacitance and voltage/temperature ratings (these may be written on the part itself, or you can look up the part number).
Press the tip of a heated soldering iron directly onto the solder joint on the back of the circuit board that is holding the old capacitor down. Hold on to the capacitor itself with your other hand. As the joint melts, you can feel the tip of the iron fall into the hole of the circuit board. As soon as it does, pull that side's wire lead out of the board. Then repeat with the other side.
This can take a bit of trial and error. The goal is to dig the very tip of the iron into the joint so that the solder in the hole heats and melts. If there's too much solder for your iron to reach the hole itself, you may want to use a soldering wick to get rid of some of the excess.
Also, be aware that some manufacturers use solder that cannot be melted by a typical hobbyist soldering iron.
Step 5: Insert the New Capacitor
Trim the leads of the new capacitor so that they are both even, and will sit at about the same height as the old capacitor.
Position the new capacitor leads at the holes where the old capacitor was, with the correct polarity. Just like before, press the tip of the soldering iron directly onto the joint in the back of the circuit board. As soon as the tip falls into the hole, press the wire lead through the hole, then remove the iron. The old solder joint will solidify around the new part and hold it secure. Repeat with the other side. Add new solder to the joint if necessary.
Step 6: Working Now!
Replace the circuit board in its case and test the power and output. The electronics should work now!
HelloKitty3636 made it!
We have a be nice policy.
Please be positive and constructive.
Hi. I'm being challenged by this board sitting in a "bathtub" filled with about 1/16" of clear latex. Does anyone have experience on which route should be taken? I could cut away the plastic behind the board but the goo has me a bit concerned. The caps are 11mm tall so I can get my tweezers around them, but will they release without damaging the surrounding board?
The other option would be to attack from the top -- grind, peel, pluck, and vacuum -- leaving just the leads. Has anyone done this with positive results? I was thinking about soldering some sleeve connectors for future change outs of these caps without pulling the board again.
It's the CPU for a Rheem tankless water heater (and I really hate cold showers, especially in winter!).
Any insights are very much appreciated, and I'll send some more pictures if anyone is interested in The Latex Challenge.