Start at the beginning

Check the supply voltage at TB5 (EZ) or TB6 (PRO).

PRO (3 or 4 axis)12VDC36VDC42VDC10A (4 axis)
7.5A (3 axis)

See the Power Supplies FAQ for more info on delivering power to the boards.

Check 24V at the fan connector

Confirm 24 Volts at the fan connector at TB6 (EZ) or TB7 (PRO). This voltage will be affected by your power supply voltage. If your power supply is less than about 26 Volts DC, then you will read less than 24 Volts at the fan connector (roughly 2 volts less than your supply voltage)

Do you have anything besides a fan connected to this connector? the MAXIMUM draw from this connector is 300mA (0.3A) without a heatsink. Connecting anything other than a fan is not advised.

Confirm 5VDC at test point

Check The test point labeled +5 VDC.  Put the negative (black) meter lead on the “-” (minus) of the power connector TB5 (EZ) or TB6 (PRO).  Put the positive (red) meter lead on the +5 VDC test point

99% of the time this is a solder bridge somewhere on the board. Examine the board under bright light with a magnifying glass, I found my short on the component side between the two rows of pins of one of the driver chips, very hard to see.

Do you have anything else drawing from the 5 Volts on this board (like a relay board or an opto board)? Don’t do that. The regulators on this board are designed to support this board ONLY, and a fan (see “Check 24V above)

Voltage at the Axis test points

Each axis has a blue-topped variable resistor (trim pot) to set the amount of current provided to each stepper motor. Measure the voltage at each TP (located physically next to that blue-topped variable resistor). Put the negative (black) meter lead on the “-” (minus) of the power connector. Confirm against the manual.

Use the calculator to the right to determine the proper voltage for the desired current. This is for both the PRO and EZ boards.

Regulator getting hot

This would likely indicate excess current draw somewhere ‘down the line’ from the regulator.

Which regulator is which

PRO – 24V = U6.   5V = U5.    “Pre regulator” (enables higher input voltages on PRO board) = U7

EZ – 24V = U5.   5V = U4