Have a computer that won’t power up? You may have to go old-school and break out the soldering iron. Here’s why –
If you computer is not coming on and you have checked everything you can think of including, the power supply, unplugged the hard drive, CD/DVD, checked the memory and when you are out of ideas, stop and check the capacitors. Capacitors are cylindrical components that are marked with voltage and a capacitance rating (see link at the end of this article).
If you look at the end of the capacitors, you may notice one or more of the them may be swollen on the end or it may actually be leaking. This is probably your problem component.
A normal capacitor should look like this on the end.
A leaking capacitor may look like this on the end or it may be swollen.
A capacitor’s capacitance can decrease as the it ages. As your motherboard heats up and cools over time, the constant exposure to heat (or substandard capacitors) can cause a breakdown. This in turn can cause the capacitor to leak or to swell.
To fix this problem, it often is worth trying to re-solder a new capacitor to the motherboard if the motherboard is no longer manufactured or you have to have the computer operational.
In our case, we have several four year old quad core computers worth saving. The motherboards are no longer manufactured and replacing the motherboards can cost more than the computer is worth.
Where to start
Note: This is a basic tutorial and by no means a thorough how-to. Get help the first time you attempt this.
Start by making sure the computer is unplugged. Make sure you have the proper tools such as solder, flux, a good soldering iron, a new capacitor or a capacitor from an older motherboard that appears to be good. You would be surprised at how many components are reused by hobbyist.
Your replacement capacitor should match the capacitance and voltage (There’s other tricks that are out there but we will stick with a basic replacement). Use an anti-static mat and make sure you properly handle the motherboard trying not to expose the other components to static discharge.
Remove the motherboard from the case. Because of the manufacturing process, often trying to desolder the old component can cause damage. This will of course depend on the manufacturer and how much heat you have to apply. Ultimately it is your goal not to damage other components or the motherboard itself. With many capacitors, you can slowly work the old capacitor off by pulling on it carefully until you pull the main leads out of the old capacitor. This way you have applied zero heat.
Always note the orientation of the capacitor when you remove it from the motherboard. Now trim the wires that are left on the motherboard.
Here’s the part that can keep you from damaging the motherboard’s other components.
Remember, you made note of the orientation of the capacitor earlier? Flip the motherboard over and note where the solder contacts that would be opposite of the top of the motherboard where the capacitor was connected. This is where we will solder the new capacitor. Double check yourself before going further. Draw a circle with a sharpie around the contacts if you need to.
What is another reason we flipped the board? It is often easier to solder on this side of the motherboard due to the soldering process that took place at the manufacturer.
Use 1″ length wires from solid Cat 5 cable or any wire that is around 22 gauge wire if you are using an older motherboard’s harvested capacitor that matches the capacitor you are replacing. You can solder these leads onto the capacitor and then onto the motherboard.
Soldering takes practice. The information in this article does not cover how to solder. Get a friend to help you the first time.
Again, check the orientation and check to make sure you are soldering on the correct connectors. Newer capacitors will have adequate leads. Note the small hooks on the leads to get a complete connection.
While the picture above may not look neat, we were down to one hour before show time with zero computers to spare. With good solder joints and the proper capacitor, the computer immediately powered on and ran stable.
Use a small piece of electrical tape to hold the capacitor to the motherboard. You have to remember to replace all of the capacitors that look blown or that may be leaking. You also have to remember that if you have a future problem with the computer again, that this is another point of inspection.
While there are dozens of things that can go wrong electronically on a motherboard, the most likely cause is leaking or bad capacitors.
We’ve had many ‘saves’ by replacing capacitors. This has allowed us to bridge over to a new financial year and we have had motherboards to last years after replacing components. While motherboards today can range from $50 to $500+, many proprietary boards come in specific cases with specific connectors and the cost for mixing and matching parts can exceed the cost of a new computer. In the real world, you may not have spare parts readily available and you may just have to do this. There are a million scenarios that are out there where learning to solder may come in handy.
The decision is ultimately up to you. Remember to be safe and to take your time. There is never a guarantee that this will work.
Want to know more about capacitors? Wikipedia has a good article to show you just how complex capacitors can be.
Want to learn how to solder? Your best option is to find a friend who knows how. While there are many tutorials on the web, try practicing with an old motherboard and components.