Mitsubishi MELDAS MDS-C1 Instruction Manual page 167

(5) Confirming the Z phase pulse width
Check the output signal waveform by measuring the signals of the check terminals on the PCB
with the DC range of the synchroscope.
A phase output signal........ Across A-G
Z phase output signal........ Across Z-G
The output signal waveform is confirmed during motor forward run and reverse run. Set the
synchroscope as follows to measure the waveform during each run direction.
During forward run ............ Apply a trigger at the rising edge of the Z phase output signal
During reverse run ............ Apply a trigger at the falling edge of the Z phase output signal
Confirm that the Z phase pulse width (time that the Z phase signal is at the "H" level = approx. 15V)
is 40% or more and 60% or less, when one cycle of the A phase signal is calculated as 100%. The
normal Z phase output signal waveform when run at the reference speed is shown below. If the
output signal waveform is not as shown below, refer to the next section "(6) Adjusting the Z phase
pulse width" and adjust.
The Z phase pulse width has been adjusted at shipment, with a combination of the sensor section
and PCB section having the same serial No. Thus, it normally does not need to be adjusted. If a
sensor section and PCB section having different serial numbers must be used, causing the Z
phase pulse width to deviate from the specified range, carry out the adjustment.
One A phase cycle = 100%
A phase
Q point
0V
Z phase
Z phase pulse width: 40 to 60%
A phase/Z phase output signal waveform
during forward run
(6) Adjusting the Z phase pulse width
The Z phase pulse width can be adjusted with potentiometer VR5 on the PCB. VR5 is fixed after it
has been tested and adjusted to match the sensor section and PCB section having the same serial
No., so do not turn it unless a sensor section and PCB section with different serial numbers must
be used.
3. Setup
Apply a trigger at the rising
edge of the Z phase
H level (reference
voltage +15V)
L level
3 - 88
One A phase cycle = 100%
A phase
R point
0V
Apply a trigger at the falling
edge of the Z phase
Z phase
Z phase pulse width: 40 to 60%
A phase/Z phase output signal waveform
during reverse run
H level (reference
voltage +15V)
L level