PERFORMING ELECTRONIC TESTS
Do You Need To Test Or Troubleshoot A Device?
Typical digital multimeter
Electronic testing is an essential skill in advanced troubleshooting. You need to practice safety and know some basic electronic knowledge to perform the diagnostic procedures required to attempt most repairs. It is important to be able to follow the path of electricity from its power source to the point(s) of application. If you understand the concept of "ground," can plug in the leads correctly into a multimeter and set the function selector properly, then we can show you what to do. You can trace the path of electricity from its primary source, (plug or Battery) to the circuits, connectors and displays it powers.
Start by clearly defining what the problem is. Is it a mechanical failure? Is it a broken Part? Is power being supplied properly? Is it being properly turned on? Is there a reset procedure? Your first and most important step is evaluation! Please take at least five (5) minutes to examine the equipment from every angle possible. Now, here comes the questionaire. What happened when the device was last used? When did it first fail? Has it ever failed before? What went wrong then? Were the symptoms the same? Are the symptoms consistent or sporatic? Does it work partially or at all? Is there any sign of power?
Now we are ready to begin testing for power. Start at the source. How is it powered? Is it from a wall socket, a battery or both? If there are no batteries involved test your outlet first. The standard A/C outlet In the U.S. will produce between 110 and 120 volts. You can easily check the outlet with your meter by adjusting your selector dial or switch to A/C volts and making sure your probes are inserted into the (-) com and the (+) voltage ports, black and red respectively. Carefully insert your probes into the wall outlet in question and see if the reading is correct. The same voltage found at the outlet will also be found at the other end of the A/C power cord plugged into the outlet.. Another measurement can be made here to confirm that the main power cord is good. The A/C supplied here is your source of power. If the device is battery powered and utilizes two sources you will need to determine which is the primary and how to isolate it. Usually devices powered exclusively by batteries have an easily accessed battery compartment and no external ports for power if the batteries are not rechargable. Once the "power source" is determined, the primary concern is the "power supply" and its related circuitry. This distinction must be firmly establish. The power source is the origin or place the power comes from. There is generally not much control over it. The "power supply" takes the source through its circuitry and adjusts or converts the power through components or circuits designed to invert, regulate, or transform it. After this process is completed the changed new proper current and voltage(s) will be available to operate the device . Good measuring points are commonly found at plug in connections used to supply or share power among various boards Look very carefully at the PCB (printed circuit board), many times voltages are discretely labeled right on the board. If you are sure that your primary source of power is good and reaches the power supply input, you can now test the power supply. There are several common components in most power supplies. Start with the fuse. UNPLUG THE DEVICE NOW! REMOVE THE CABLE, LINE, CONNECTOR, OR POWER CORD FROM THE BATTERY, WALL SOCKET OR WHATEVER POWER SOURCE IS CONNECTED TO IT! The fuse is designed to stop higher than normal current flow to the electronic circuit its connected to. Performing a continuity test on the fuse reveals if it good. To check continuity you must remove the fuse and KILL the power, do both if possible. Adjust your selector dial or switch on your meter to ohms, continuity, or diode test. Just touching the probes together will cause the display to indicate no resistance, 0.00 (a short), instant needle deflection, and or an audible tone. These are the same results you should get when you hold the meters probes to both ends of a good fuse. If your fuse tests good you will have to plug the device back in and first check for LIVE voltage on both sides of fuse and then trace live voltage paths. Tracing live voltage is dangerous and can be hazardous. Any furthur test from this point are at the component level. Tests need to be made at transformers, bridge rectifiers, capacitors, voltage regulators, resistors and connectors. Only attempt live testing like this if you KNOW what you're doing.
Start by clearly defining what the problem is. Is it a mechanical failure? Is it a broken Part? Is power being supplied properly? Is it being properly turned on? Is there a reset procedure? Your first and most important step is evaluation! Please take at least five (5) minutes to examine the equipment from every angle possible. Now, here comes the questionaire. What happened when the device was last used? When did it first fail? Has it ever failed before? What went wrong then? Were the symptoms the same? Are the symptoms consistent or sporatic? Does it work partially or at all? Is there any sign of power?
Now we are ready to begin testing for power. Start at the source. How is it powered? Is it from a wall socket, a battery or both? If there are no batteries involved test your outlet first. The standard A/C outlet In the U.S. will produce between 110 and 120 volts. You can easily check the outlet with your meter by adjusting your selector dial or switch to A/C volts and making sure your probes are inserted into the (-) com and the (+) voltage ports, black and red respectively. Carefully insert your probes into the wall outlet in question and see if the reading is correct. The same voltage found at the outlet will also be found at the other end of the A/C power cord plugged into the outlet.. Another measurement can be made here to confirm that the main power cord is good. The A/C supplied here is your source of power. If the device is battery powered and utilizes two sources you will need to determine which is the primary and how to isolate it. Usually devices powered exclusively by batteries have an easily accessed battery compartment and no external ports for power if the batteries are not rechargable. Once the "power source" is determined, the primary concern is the "power supply" and its related circuitry. This distinction must be firmly establish. The power source is the origin or place the power comes from. There is generally not much control over it. The "power supply" takes the source through its circuitry and adjusts or converts the power through components or circuits designed to invert, regulate, or transform it. After this process is completed the changed new proper current and voltage(s) will be available to operate the device . Good measuring points are commonly found at plug in connections used to supply or share power among various boards Look very carefully at the PCB (printed circuit board), many times voltages are discretely labeled right on the board. If you are sure that your primary source of power is good and reaches the power supply input, you can now test the power supply. There are several common components in most power supplies. Start with the fuse. UNPLUG THE DEVICE NOW! REMOVE THE CABLE, LINE, CONNECTOR, OR POWER CORD FROM THE BATTERY, WALL SOCKET OR WHATEVER POWER SOURCE IS CONNECTED TO IT! The fuse is designed to stop higher than normal current flow to the electronic circuit its connected to. Performing a continuity test on the fuse reveals if it good. To check continuity you must remove the fuse and KILL the power, do both if possible. Adjust your selector dial or switch on your meter to ohms, continuity, or diode test. Just touching the probes together will cause the display to indicate no resistance, 0.00 (a short), instant needle deflection, and or an audible tone. These are the same results you should get when you hold the meters probes to both ends of a good fuse. If your fuse tests good you will have to plug the device back in and first check for LIVE voltage on both sides of fuse and then trace live voltage paths. Tracing live voltage is dangerous and can be hazardous. Any furthur test from this point are at the component level. Tests need to be made at transformers, bridge rectifiers, capacitors, voltage regulators, resistors and connectors. Only attempt live testing like this if you KNOW what you're doing.
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