Snap-On UHR Ultra, Руководство по обслуживанию

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CHAPTER 1
AC/DC POWER DISTRIBUTION
ELECTRICAL SAFETY PRECAUTIONS
Make sure the aligner is unplugged before disconnecting any wires in preparation for replacing any boards,
cables or other items within the unit. Use the
“Lockout and/or Tagout” procedure.
When working on this aligner, keep three points in mind:
THIS UNIT MUST BE PLUGGED IN TO A PROPER AC OUTLET FOR
THE UNIT TO OPERATE CORRECTLY. REFER TO THE UNIT ID
PLATE LOCATED ON THE BACK OF THE UNIT. EXTENSION CORDS
ARE NOT RECOMMENDED, BUT IF AN EXTENSION CORD MUST BE
USED, USE A CORD THAT IS LESS THAN 50 FEET WITH A 16 AWG,
OR ABOVE 50 FEET AND LESS THAN 100 WITH A 14 AWG.
!
USE STANDARD ANT-STATIC PROCEDURES
WHILE PERFORMING THESE INSTRUCTIONS
1. Aligner voltages refer to the “return” (white) side of the AC line. Yet sometimes outlet wiring is reversed.
In that case, electrical neutral connects to the “hot” side of the line. The aligner operates normally, but the
PC board floats 110 VAC above safety ground. Assume that points inside the aligner console are at
110VAC ; observe all safety precautions. If you make measurements with grounded test equipment, use
an isolation transformer. An oscilloscope is an example of such test equipment.
2. The aligner is susceptible to power line spikes and noise.
You must connect the equipment to safety
ground
. Does your machine do “strange things” or exhibit intermittent problems? Check for a proper
ground at the machine and the power outlet. If you’re using an extension cord, check that, too. It must be
constructed of at least 16 gauge wire and under 50 feet long.
3. Schematic voltages refer to the “return” side of the line, not safety ground. When measuring AC voltages,
use the white wire on the line power terminal block as ground. Don’t use the third, center safety ground
terminal. Another place to access ground is at the shield. The black wire in the shielded transducer
cables also connects to the ground return.
HANDLING STATIC SENSITIVE PCB’S
Electrostatic discharge can destroy high impedance ICs if uncontrolled. Use the fol-
lowing techniques to avoid damaging ICs:
- Leave new circuit boards in their antistatic bags until ready for use.
- When replacing boards, proms, etc. be sure to turn off power to the machine first
- Use an anti-static wrist strap. Connect it to chassis ground on the equipment or to an available raw ground.
- Touch the chassis of the equipment to put yourself at the same static potential as the equipment.
- Grasp the PCB from opposite sides using your fingertips. Do not grasp the components on the board.
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