Page 5.7
Chapter 5
Adjustments
SCHILLER AT-2plus 6-Channel ECG Unit
SERVICE HANDBOOK Issue 1 June 1998
Paper mark Detector Check
Tools, Equipment and Material
Digital voltmeter
Small flat bladed screwdriver
70% alcohol solution and clean lint free cloth
Procedure
To adjust the paper-mark Schmitt trigger sensitivity proceed as follows:
DISCONNECT THE MAINS SUPPLY
Open the paper tray lid and clean the photocell (situated on the opposite side to the dc
motor) with a 70% alcohol solution. Allow to completely dry.
Disassemble the unit as detailed in Chapter 4.
Reconnect the keyboard to the Control board and place the top assembly on its side in front
of the Base assembly .
Switch the unit on and set the speed of the printer to the slowest setting of 5mm/s (5mm/s
key).
Press the MAN START key to activate the printer. The paper is now moving at low speed
(through the roller and paper mark detector).
Check the pulse amplitude at P8 pin 1. (Measure with AC setting, signal is noisy.)
no paper-mark (white paper) between -80mV and -200mV
paper mark (black paper) between -5mV and -30mV
Reassemble the unit as detailed in Chapter 4.
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