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Service Guide ML393/ML393CPlus
Chapter A Board Diagrams
A.2.01 Main Control Board (LQEM)
Firmware
Q6 - Program ROM of Master MPU
Q7 - Character Generator ROM
Q17 - Program Rom of Slave MPU
Fuses
F1 2.0 Amp 125V
Jumpers
SP1: OPEN - Internal ROM
SHORTED - External ROM
SP3 OPEN - Monochrome Model
SHORTED - Color Model
Sensors
NONE
Switches
NONE
Test Points
+ 38vdc
Printhead, SP Motor, LF Motor and Bail/Ribbon motor drive voltage.
Check on both ends of Capacitor C2.
+ 5vdc
Logic IC/LED drive voltage.
Check between pin 16 of Q2 and the power bar.
+ 8vdc
Line feed motor holding voltage and serial interface line voltage.
Check on both ends of C9.
- 8vdc
Serial interface line voltage.
Check on both ends of C8.