Epson LQ-570 Service Manual page 33

REV.-A
4.3 CIRCUIT ADJUSTMENT
The C107 board contains variable resistor VR1, which is used for balancing the circuitry. When any of the
MAIN
following parts are replaced, the circuitry must be balanced by adjusting the VR1.
R6, R7, TL431(IC1), and VR1
If the circuitry is not properly adjusted, the CPU A/D converter functions abnormally and causes irregular operation
of the printer.
4.3.1 Adjustment Process
Attach a digital multimeter to the check terminal TP1 (Vref voltage) on the C107 MAIN board. Turn the printer On
and adjust the variable resistor VR1 until a reading of 4.741 V is obtained.
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