Background
The idea of providing power to your machine seems simple: just plug it in. In reality, there are a number of other components used in order to provide power appropriately safety for you and the machine, including (but not limited to):
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The main disconnect switch
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Fuses and/or circuit breakers
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Emergency stop switch/button
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Separate latching circuits for the spindle and rest of the machine
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Transformers, which change the electricity to the appropriate value
Even with all of these components, you can systematically locate nearly any problem with just a multimeter.
Tools
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Multimeter
Twist Out the Emergency Stop Button
Reason: The Emergency Stop button is pushed in.
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Twist out the Emergency Stop button and press the Reset button.
The Reset button doesn't illuminate until after you:
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Twist out the Emergency Stop button.
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Press the Reset button.
Reset the Building’s Mains Breaker
Reason: The shop or building’s mains breaker is turned off.
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Examine the building’s breaker. If it’s not already on, turn it on.
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Using a digital multimeter, measure to inspect and verify that you have power at the outlet.
Inspect the Power Entering the Machine
Reason: The Main Disconnect switch is in the Off position.
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Examine the Main Disconnect switch. If it’s not already in the On position, turn it on and try to take your machine out of reset.
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Measure the voltage coming out of your Main Disconnect switch.
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Identify the wires as indicated in the table.
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If you measure the correct Vac, continue.
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If you do not any Vac, you either have a loose wire or a faulty Main Disconnect switch.
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Machine |
Wires |
Measure for… |
---|---|---|
PCNC 770 |
91 and 100 |
120 Vac nominal |
Check the FU1, FU3 and FU6 Fuses
Reason: Fuse is blown.
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Identify your machines main fuses.

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Power down the machine, and remove both fuses.
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Check both fuses using the following process: Checking a Fuse on a Tormach Machine
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If any fuse is blown, replace it.