42114101 Rev.1
133 /
No
Replace the Q2.
Yes Replace the Q3.
A
Yes Are ALE, PSEN, RD, WR, signals as specified in Figure C-6?
Figure C-7
542ns
180ns
271ns
542ns
5V
0V
5V
0V
5V
0V
ALE
PSEN
RD/WR
Figure C-6
ST bit
SP bit
5V
0V
5V
0V
RxD
SSD
No
Replace the Q3.
Yes Are (T1) SELECT and (INTO) BUSY signals low level?
No
Check Q3 on the Control Board.
Yes Are +9V and -9V input to Q1?
No
Replace defective component in +9/–9 volt control circuit.
Yes Is pin 1 SSD signal of Q3 High level?
No
Replace the Q3.
Yes Is pin 11 SSD of Q1 low level?
No
Replace the Q1 or the CN1?
Yes Is the RxD of Q3 as specified in Figure C-7?
Summary of Contents for ML490 Series
Page 1: ...42114101 Rev 1 1 135 ML490 491 PRINTER Maintenance Manual ODA...
Page 2: ...42114101 Rev 1 2...
Page 38: ...42114101 Rev 1 38 Drive gear Ink tank Ribbon cartridge Figure 2 6...
Page 48: ...42114101 Rev 1 48 Change arm Change lever Platen Release cam Figure 2 13 REAR TOP BOTTOM...
Page 96: ...42114101 Rev 1 96 9 Carriage Assy NK2 10 SUS Bearing portion of guide roller EM 30L B...
Page 119: ...42114101 Rev 1 119 6 8 9 7 1 2 3 11 10 4 5 Figure B 2 Printer General Assy...
Page 124: ...42114101 Rev 1 124 9 12 11 1 13 3 7 1 14 5 6 7 2 10 8 Figure B 4 Carriage Assy...