Pacific Laser Equipment 1SA-1000 - Manual (Page 14)

Servo Amplifier 1ch-1000 User manual
1SA-1000
April 28, 2004 Release: 1.21 2003 by Pacific Laser Equipment
PLEquipment, 3941 S. Bristol St. Unit E, # 122, Santa Ana, CA. 92704, ( & Fax: 509-355-5155, Email: [email protected]
Page 14 of 16
8. Troubleshooting and test
Zero point calibration
To be adjusted in EC mode and 0V analog input and zero DC offset to –5(0)V on the display.
High voltage output
Attention:
The HV output can reach –1200V. This is a dangerous voltage. A spark can jump 10mm.
Test in VC mode. At 10V analog input the display should read –100(0) V.
Monitor out
Can be tested in VC or EC mode.
At 90microns displayed on the digital display the voltage should be 10V.
At 0microns displayed on the digital display the voltage should be 0V.
SGS excitation
On pins 1 and 5 of the Sensor input connector on the front panel, the SGS excitation should be
approximately 5V DC.
SGS integrity.
If the Weatstone Bridge is interrupted the closed loop operation of the piezo actuator becomes
impossible. This failure mode signals an imminent breakdown in the ceramics stack due to
developing micro-cracks.
The resistance between the SGS connector pins can be measured and the values should be
700 or 1400
Ω
or 500 and 700
Ω
.
Piezo integrity.
Attention:
All piezo actuators are very fragile, they should be always treated like VERY BRITTLE.
A simple ohmmeter resistance test should read an average resistance higher than 2M
Ω
This is a marginal value. Typical values are higher than that in the 8M
Ω
range.
A more accurate test is the current leakage test performed with the piezo at max. operating
voltage and an Amp-meter in series in the HV circuit. A good value should be under 10
µ
A.
This is also a marginal value. Typical values are lower than that in the 4
µ
A range.
The current consumption increases to mA in dynamic operation of the actuator due to repeated
charge /discharge cycles.
Applying reversed polarity on the piezo will depolarize the ceramics and cause failure.
Avoid high temperature directly applied to the ceramics. The max. spec. is 175
°
F.
Fuse
Check the main fuse on the rear panel. When replacing it, use slow-blow 120V, 100mA.
AC Power
Make sure that the power used is always 120V.