INTRODUCTION

You don’t have to be an experienced engineer, technologist or technician to find some obvious fault on circuit boards. You can find circuit boards in virtually all your gadgets, from your DVD player to your TV, home-theatre system, PC and so on.

The most common type of fault you find is that your techno-gadgets refuse to power on. You might not need to go all the way to a technician to fix this fault.

In this post, we will take you through a step by step approach to finding faults on your electronic circuits but first, the following tools will be required and they will come in handy. With this you can figure out the fault and DIY (Do It Yourself) with an inexpensive cost.

  1. Screw driver( flat or star type, depending on the screws on your gadget)
  2. Multi-meter( with probes, for measuring resistances and voltages)
  3. Soldering iron(as well as soldering lead)
  4. De-soldering pump

With all these handy tools, you are on your way to finding the fault on your circuit board.

Follow the steps below to get started.

STEP 1

Before dissembling the system, ensure the system (for example, your DVD player) is disconnected from the mains. That is, all plugs used to supply power to the system is pulled off from the wall socket or mains.

This is required, especially if you are inexperienced about electricity, to avoid been electrocuted or been jolted by shock.

STEP 2

Remove all screws found on the body of the system, with the screw driver, till you are able to see the circuit boards mounted inside the system. Be careful, some components on the board may still have some charge on them enough to give you a shock or electrocute you. We wouldn’t want that, would we?

So, you can wait for some few minutes for the capacitors to discharge or you can forcefully discharge them yourself if you are experienced.

Most gadgets consist of several panels/circuit boards, which you might find out as you have dissembled your system, but for the purpose of this post, we will dwell only on the power supply board.

STEP 3

This step requires us to do a visual inspection of the power supply board. There are few things to look out. Here is a list of things to watch out for;

  1. Some power supply circuit boards have on them a fuse used to protect the circuit from overload or over-current. If your circuit is contains a fuse, check to see if the fuse is blown. This would likely have the glass of the fuse stained. if this is the case, the fuse has to be replaced, it is blown.

  2. Check to see if you have a blown capacitor on the circuit board. This could be visible to the eyes. You could have a situation where the capacitor is bulged, for example, see the below image. Sometimes, this might be in the form of the electrolyte leaking out of the capacitor or in another case you see an unusual lifting of the capacitor off the board. These signify a bad CAP. They need to be replaced.

Identifying a bad capacitor
  1. Another lookout should be for cold solder joints. Any joint you suspect of not having a good connection with the board and component being soldered needs to be re-soldered. You can verify if a joint has a cold solder by gently moving the component to and fro and see if the joint is lifting off the board.

Cold Solder Joint
  1. Lastly, check for discoloration of other electronic component, such as, resistors. A discoloration indicate the resistor is shorted or open. Therefore, there is a need for replacement

STEP 4

The next approach is to change all the bad CAPs, blown fuses, resistors. Gently de-solder the faulty component on the board and replace with new ones of the same marking. For example, if the faulty capacitor is marked 35V, 22uF, the new one should have the same marking.

With the above steps followed carefully, you are definitely on your way to becoming a pro at fault finding.

However, most times, the bad components observed visually are as a result of other component gone bad which are not visible to the eye. A more thorough approach then needs to be taken, which involves the use of your multi-meter to test at different point of the circuit and compare the reading with known values, to see what other component might have gone bad.

I hope this post was helpful.