Dyna Myte DM2016: Resolving Error 378 and Axis Faults

A Dyna Myte DM2016 with the Dyna Mechtronics 4M control can report error 378 even when the servo amplifiers and motors are not the primary cause. In the documented recovery, the first control-side fault was a controlled-axes parameter set to 000. After that correction, amplifier faults, mechanical binding, missing Z-axis hardware, encoder wiring, PID tuning, and zeroed tool-change positions had to be resolved separately.

Interpret Error 378 Before Replacing Hardware

The control displayed 378 "DRV: In disable state!(1-X,2-Y,4-Z,8-Z,16-U) (-15)", prevented jogging and homing, and initially coincided with red fault LEDs on all Advanced Motion B40A20I servo amplifiers. The duplicated Z designation in the displayed text is retained here exactly as observed; the available evidence does not resolve whether it was a display error or represented another configured axis.

Establish the Electrical and Safety Baseline

Perform live measurements only under the site's electrical safety procedure. Remove power before turning a ballscrew, changing amplifier connections, or moving motor, Hall, encoder, and phase conductors.

1. Check the keyboard emergency indicator. A flashing indicator was described for an emergency-stop input or axis overtravel circuit. Those circuits were reported as normally closed, so an open switch or conductor can assert the condition.
2. Confirm in the PLC ladder and at the relevant connector pins that travel limits, oil/air inputs, and other interlocks are not active. The recovered machine showed none of these inputs tripped.
3. Measure the incoming supply. The documented machine rating was 220 VAC ±10%. Measure every incoming leg to earth and keep any wild or high leg away from the large gray control transformer.
4. Measure the three-position screw terminal strip along the lower-right edge of the main board. The two occupied terminals must measure approximately 117–123 VAC; the recovered machine measured exactly 120 VAC. Correct an out-of-range reading with the gray transformer's taps because the AMC DC supply is unregulated and the main board can inhibit amplifier enabling when this voltage is outside the stated range.
5. Verify the main control board receives +5 V, +12 V, -12 V, and 24 V.

The documented power architecture used three-phase power for the coolant pump or pumps and the spindle motor/amplifier, while the remaining control load ran from single-phase power through the gray transformer. The recovery temporarily powered the transformer from a single-phase 220 V source, but the evidence also warns that operating the spindle drive from single phase stresses its bridge and DC-bus capacitors. Treat that arrangement as a diagnostic condition, not evidence of an approved conversion.

Correct the Controlled-Axes Parameter

When error 378 appeared without a preceding error, manufacturer support identified an all-zero axis definition as the control-side cause. The controlled-axes user parameter was 000, disabling all axes. Changing it to 111 enabled the installed X, Y, and Z axes. The servo-enable LED then remained green until a motion command exposed separate axis faults.

A machine missing its Z motor and amplifier could instead use 011. In the documented configuration, that setting disabled Z while allowing X and Y to home; the position display then changed to zeros, MDI became available, S codes could be entered, and the two active axes executed a G3 move. Use this only when Z is intentionally unavailable. Do not ground an amplifier fault line as a substitute for configuring the controlled axes: suppressing the reported fault did not satisfy the homing requirement or make the absent axis operational.

Verify Amplifier Enable Polarity and Isolate Faults

The B40A20I enable input on this machine did not follow the initially assumed polarity. The amplifier installation information available during the repair indicated that its enable logic could be reversed by a switch or an SMT jumper. Grounding pin 9 produced a green amplifier indication on the installed units, confirming that this machine used reversed logic. Determine the fitted logic state before applying an enable signal; do not assume the standard shipping polarity.

1. With the controlled-axes definition corrected, observe whether an amplifier remains enabled while stationary and faults only when jogging begins.
2. Swap the X and Y amplifiers while preserving a traceable connection record. If the problem stays with the physical axis, investigate mechanics, motor wiring, feedback, and axis cabling. If it follows the amplifier, treat the amplifier as faulty.
3. Do not infer that every red LED represents several failed amplifiers. The initial simultaneous indication cleared when the enable/configuration problem was corrected.
4. After any repair, test the suspect amplifier on the known working motor and the known working amplifier on the suspect motor. In the documented failure, the working Y amplifier drove the X motor, while the failed X amplifier remained dead on the Y motor; this isolated the amplifier.

The original amplifier's part number appeared to be specific to the machine supplier, while a similarly named non-isolated model was also encountered. Isolation equivalence was not established in the evidence, so match the complete model and interface requirements rather than substituting solely by a similar base number.

Check Mechanical Binding Before Increasing Current

The Y axis produced a thump and faulted when jogging even though its amplifier showed green at rest. With power removed, the Y screw was initially extremely difficult to rotate. Manually walking the mechanism through part of its travel reduced the resistance until it was only slightly stiffer than X. After reassembly and another power cycle, Y moved normally.

This behavior supports a mechanical-load check before raising amplifier current or tuning gains. With power isolated, compare the force needed to move the suspect axis with a working axis, inspect the ballscrew and coupling, and free any confirmed binding. Then reconnect the original electrical configuration, cycle power, and test a low-risk jog. A stationary green LED followed by a thump and immediate fault is not proof of an electronic failure.

Commission a Replacement Z Motor and Feedback Loop

The delivered machine lacked both the Z-axis servo motor and amplifier. Its replacement used a Parker motor with the same bolt circle as the original SEM motor and a separate Advanced Motion amplifier whose connectors differed from the original 16-pin header. This required a traced interface rather than a pin-for-pin adapter assumption.

1. Trace the known axis encoder wiring. The motor-side board identified eight signals: A+, A-, B+, B-, Index+, Index-, +5 V, and ground.
2. Trace every conductor through intermediate cables to the Dyna main board. The documented board labeling was misleading: pins 2 and 3 at the relevant control-board connection proved to be index positive and index negative rather than A positive and A negative.
3. Verify both quadrature channels while turning the motor slowly by hand. The observed healthy signals were clean square waves with a 90-degree relationship in one direction and 270 degrees in the other.
4. Determine compatible motor-phase and Hall combinations systematically. A wrong combination produced only a thunk or motion in the wrong direction. Motor phase conductors were reversed when the axis attempted to move down instead of toward home.
5. Close the position loop before increasing current. With the current setting near 50%, the incorrectly wired motor ran away and traveled about 10 inches in one second before a position-tolerance error stopped it.
6. After correcting the encoder conductors at the 9-pin control-board connector, tune the existing PID settings until the previously jerky motion becomes smooth. The evidence does not provide transferable numeric PID values, so tune against the actual motor, load, amplifier, and feedback combination.

A runaway is a feedback fault until proven otherwise. Stop motion, isolate power, and verify feedback polarity and channel assignment instead of attempting to stabilize an open or incorrectly closed position loop with gain changes.

Restore Tool-Changer Positions

Once three-axis motion worked, a tool command sent Z home and moved the carousel inward, but the sequence stopped with a home-dog message. The upper and lower tool-change user parameters were both set to 0. After measuring the required locations and entering those positions, the machine picked up and returned a tool.

1. Confirm Z homes repeatably and its position loop remains stable.
2. Inspect the upper and lower tool-change position parameters. Treat zeroed values as lost setup data, not confirmed machine coordinates.
3. Measure and enter the actual machine-specific positions. The evidence supplies no universal coordinates.
4. Run the exchange cautiously and verify carousel engagement, pickup, and return before using automatic operation.

Verify Recovery Through the 4M Control

Complete the repair with functional checks rather than relying only on fault LEDs. Home every configured axis and confirm each reports OK. Jog each axis independently, execute a coordinated move, and then run a controlled test program. The recovered machine executed a G84 tapping cycle and later cut while moving all three axes.

The 4M display provides additional verification:

Also verify software/firmware compatibility when the machine's history is unknown. The control contained five EPROMs: three on the main board and two on the keyboard. Each carried socket and checksum identification, and the PC software had to match that firmware set. The evidence provides no version numbers or checksum values, so record the installed labels and obtain the corresponding software identification from the manufacturer rather than guessing.

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