Author Topic: Tutorial 2. Basic Troubleshooting  (Read 139 times)

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Offline Gonzo_Descente

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Tutorial 2. Basic Troubleshooting
« on: April 22, 2019, 12:46:15 PM »
Consider this circuit.  We have a Battery, B1, which we will say is a 12 Volt source.  We then have a Fuse, F1, a Switch, SW1,
then a Resistor of unknown value,  and finally a Lamp, L1.  For this part we will ignore the Resistor and pretend its not there.

Using the Voltmeter, we see the 12 Volts on the battery.  But also, since the Switch is open, we will see the same 12 Volts
across the Switch.  This is because all the voltage is across the open circuit of the Switch.

When we close the Switch, Current should flow and the Lamp will light up. We belive the ciruit is good at this point.  We
can verify 12 Volts across the Lamp.

If the Lamp does not light, the first thing to check is the Fuse.  If the Fuse is burned out, we can replace it with a known
good Fuse, and if the circuit then works, good.  However, if the new Fuse then burns out, stop.  A Fuse is not a
trouibleshooting tool.  There is a short circuit somewhere.  We will have to trace the wiring and look for a broken,
crushed, or burned wire.

Perhaps the lamp does light up, but its dim.  Use the voltmeter to measure the Voltage across the Lamp. If not full 12 Volts,
then we might have that Resistor in the circuit.  This Resistor now represents something preventing all the required
current to flow.  We now have to look for a bad connection, such as the following:  A loose fastener, a corroded terminal,
or a frayed wire, perhaps only hanging on by one strand of the wire.  WE could even have a defective Switch or a bad
 Fuse Holder.
« Last Edit: April 22, 2019, 12:48:12 PM by Gonzo_Descente »