This guide is for people interested in repairing and troubleshooting their devices. You do not need a background in electronics, this guide covers the basics. (Please note that some of the equipment mentioned here is not necessary depending on what you’re repairing.)

Must have: soldering iron, soldering tin, screwdriver set, rubbing alcohol, cotton swab (Q-tip), and some needle nose pliers.

Nice to have: solder pump, megger/megaohmeter, multimeter, heat gun, shrink wrap. Magnifying glass (little helper).

Why you should consider repairing old electronics: The answer differs from person to person. Some buy old and broken electronics, fix them, and sell at a profit. I do it to preserve my old equipment. Others do it to learn or simply for the fun and challenge. If you can’t think of any reason why you’d repair old electronics, then this guide is probably not for you.

Okay, so let’s get to it: Go find something old and simple like an amplifier/radio, LCD TV, Commodore 64, or a Gameboy. Do a visual inspection of the board. Are there any obvious burn marks? Has the board been tinkered with before? Do traces on the board cross? The most common items to find fried on a board are the resistors¹. You want to check the color coding used on the fried resistor so you can figure out what to order. There are a few phone apps you can use to find color codes. I recommend buying bulk buy resistors, since they are very cheap on the wired. Blown or bulging capacitors² quite often leave a device unable to power on. You can tell if a capacitor is damaged by looking at the top (and the bottom if possible). A good cap should be flat in those areas.

If the board is dirty, clean it! Dirty boards are not fun to work with. Blow dust off the board, and clean the rest of the dust off with a cotton swab (or several). If the board is sticky, apply rubbing alcohol on a piece of paper or cotton swab and clean it thoroughly. A lot of old cheap solder secretes a gross oily looking substance. If you see corrosion³, use a brush (an old toothbrush works fine), some rubbing alcohol and start carefully scraping away the corrosion. Corrosion can come from bad capacitors, old solder, and dirty water.

Turn on the device. Does it turn on but doesn’t do what its supposed to? Learning the right questions to ask yourself before tearing into something can save a lot of time as most electronic failures aren’t hard to fix. Sometimes old equipment gets thrown out because of water damage, and water damage isn’t as bad as it sounds in most cases, generally it should work if you leave it off for a few days to dry. If it doesn’t turn on, check the power button and fuses (if you don’t know what they look like, look up “2A fuses”. Are the fuses intact? Sometimes it’s hard to tell if a fuse is blown or it isn’t transparent. Check for blown/bulging capacitors. It is a good idea to have a few known working fuses around to test. Does the power button work properly? Sometimes old solder cracks or falls off when it gets too hot, A few minutes with a heat gun is good at fixing this. If the fuses are intact, no wires are obviously disconnected inside, and if none of the capacitors seem damaged the device might require further troubleshooting.

To find out if the board has been tinkered with before, look for wires going from one part of the PCB to other parts of the PCB, or the manufacturer date on capacitors and other parts of the board. These jobs are sometimes done badly. Is there too little soldering tin? Are the wires loose? Did the previous hacker use enough tape or too much super glue? (too much glue can lead to overheating and a blown capacitor). Are there wires twisted together where they should be soldered?

If traces are crossing, then you probably just found the issue of the board you’re fixing. If it is soldering tin that’s crossing the traces, then consider using the soldering iron to heat up the tin and remove it with a solder pump, followed by covering up the area with glue. If the traces are missing however, then you might want to bridge the traces with a small wire. (If you don’t have any, you can split open a unused Cat5e (Ethernet) cable and use them for bridging. Be warned, it can be a tedious job to solder such a small wire).

If you can’t find any obvious visual problems on the board, then the multimeter and megger can come in handy. Every multimeter is different, but they come with some basic utilities such as checking voltage, amperage, continuity and a continuity beeper. We will focus on the continuity beeper, a great tool for checking if there are trace connections between the components.

You want to first of all check the continuity of positive (+) to negative (-),

• to ground and - to earth with the megger. If it displays less than a megaohm, then there is a shortage and possible traces crossing. Do another visual check because you probably missed something. If the megger shows 1 megaohm or greater, then there are no traces crossing and you may proceed to use the continuity beeper between capacitors and other parts of the board. If you find one that does not beep, you might have found the issue.

Note: Sometimes the fluke can damage your equipment due to overcharging. Depending on how much the board can handle, you can also use the continuity beeper for checking +, -, and earth.

If you still haven’t found your problem, look up the product name and “common problems”. Sometimes electronic devices has common problems degrading or breaking a product, there should be documentation online on what the issue is and how to fix it.

Resources

• https://www.youtube.com/user/EEVblog: Great lessons on the different tools covered in this guide, as well as fundamentals of electronics.

• https://www.youtube.com/user/lukemorse1: Repairs arcade PCB’s, great for learning more about troubleshooting electronics.