Page 5.8
SCHILLER AT-2plus 6-Channel ECG Unit
SERVICE HANDBOOK Issue d May 2002
Chapter 5
Adjustments
ECG Amplifier +2V, -2V and PWM Ramp Time Adjustment
The ±2V voltage rails generated on the ECG Amplifier board are used as a reference by the
measurement and PWM circuits.
Note: The ECG board reference voltage is given on the service printout and can be
checked without disassembling the unit. Full details of the service printout are given
later in this chapter.
IMPORTANT
THE ±2V REFERENCE VOLTAGES, AND THE PWM RAMP MUST BOTH BE ADJUSTED
AT THE SAME TIME.
Tools, Equipment and Material
• Digital voltmeter
• Small flat bladed screwdriver
Procedure
• DISCONNECT THE MAINS SUPPLY
CAUTIONS
THE AT-2PLUS CONTAINS STATIC SENSITIVE CMOS COMPONENTS; OBSERVE
ANTISTATIC PRECAUTIONS . PLACE THE UNIT ON AN EARTHED ANTISTATIC MAT.
PERSONNEL MUST BE EARTHED WHEN HANDLING THE UNIT.
EXERCISE CARE WHEN REMOVING AND REPLACING CONNECTORS. NEVER USE
FORCE. NEVER STRAIN THE CABLE ASSEMBLIES.
• Disassemble the unit as detailed in Chapter 4 and remove Printer and printer tray assembly.
• Remove the Main board MK14-10 from the assembly and remove the EMC shield from the
board
• Replace the board in position
• Reconnect the keyboard to the control board and place the top assembly on its side in front
of the Base assembly .
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