Epson TM-U220 Series

Rev. B Troubleshooting 3-21
TM-U220 Type A Service Manual
Confidential
Test Points on the Main Circuit Board Unit
Table 3-30 Test Points on the Main CIrcuit Board Unit
Power supply Pin name Status
Test
connector
Component
connector
Correct
value
Power supply
Semiconductor switch on — — U9, pin 3 or pin 4 5 V
Semiconductor switch off — — Q1, pins 5 or 6 or
7 or 8
24 V
Logic circuit power
supply
Logic circuit power
supply
— — U9, pin 5 3.3 V
Logic circuit power
supply (GND)
— — Bottom
assembly frame
0 V
Mechanism power
supply
Autocutter (117) power
supply
— — F3 24 V
Print head power supply — — Q7, pins 5 or 6 or
7 or 8
24 V
Roll paper cover open
sensor (515) power
supply
Cover opened —
CN4, pin 5
3.3 V
Cover closed — 0 V
HP sensor (518) power
supply
On home position —
CN4, pin 2
0 V
Not on home
position
— 3.3 V
NE sensor (1096) power
supply
Sufficient roll paper
installed
—
CN6, pin 1
3.3 V
Sufficient roll paper
not installed
—0 V
RE sensor (514) power
supply
Roll paper installed —
CN4, pin 4
0 V
Roll paper not
installed
— 3.3 V
Drawer power
supply
— — — CNC3, pin 5 24 V