Epson 2070 Service Manual - Page 72

System Reset Circuit, 3.3 Printhead Driver Circuit, Reset Signal Output Timing

Get Epson 2070 - LQ B/W Dot-matrix Printer PDF manuals and user guides
UPC - 010343812277
View all Epson 2070 manuals
Add to My Manuals
Save this manual to your list of manuals

Page 72 highlights

Operation Principles LQ-2070 Servcie Manual 2.3.2 System Reset Circuit Control circuits IC1 and IC2 are initialized when a RESET signal (LOW level) is output from port 1 (VOUT) of IC10. IC10 monitors the +5 V line on port 3, and resets under the following conditions: IC2 E05B24YA +5V RESET 61 IC10 PST5920 VOUT 1 MRES 2 VCC 3 GND 4 R47 1K +5V C16 0.1U IC1 TPM96C041AF 23 RESET Figure 2-32 Reset Circuite 1. When the power supply is turned on, a RESET signal is output. RESET is canceled when the +5 V line goes up to 4.2 V, and then 100 ms passes. 2. When the +5 V line goes below +4.2 V, a RESET signal is output. RESET is canceled when the +5 V line goes back up to 4.2 V and then 100 ms passes. (v) 5 4 3 2 1 Power On 100ms RESET VOUT (RESET) 100ms RESET VCC (+5V line) Figure 2-33 Reset Signal Output Timing 2.3.3 Printhead Driver Circuit Print Head +35V +35V + C9 HT MP Printhead Drive Transistor Q1~Q12, Q13~24 R49 Printhead Drive Signal 69 76~89 91~99 ~ ~ Gate 28 Address 37 Array Data Line 21 44 CPU 74 73 31 15 79 78 ZD1 R50 +35V R51 +35V C19 Figure 2-34 Printhead Drive Circuit The standard voltage for the A/D converter is made in ZD1 and input to CPU port 78. Based on this standard voltage, the A/D converter in the CPU operates. Port 74 monitors the +35 V line between R50 and R51 to determine the printhead driver pulse width. Using the monitored voltage, the CPU converts the voltage to a digital value and decides the printhead driver pulse width, and then transports the data to the gate array via CPU port 15. Based on the monitored voltage, the CPU decides the printing interval. Port 73 monitors the printhead temperature to protect the printhead. If the temperature exceeds 95° C (213° F) , printing is stopped. 2-24 Rev.A

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
  • 85
  • 86
  • 87
  • 88
  • 89
  • 90
  • 91
  • 92
  • 93
  • 94
  • 95
  • 96
  • 97
  • 98
  • 99
  • 100
  • 101
  • 102
  • 103
  • 104
  • 105
  • 106
  • 107
  • 108
  • 109
  • 110
  • 111
  • 112
  • 113
  • 114
  • 115
  • 116
  • 117
  • 118
  • 119
  • 120
  • 121
  • 122
  • 123
  • 124
  • 125
  • 126
  • 127
  • 128
  • 129
  • 130
  • 131
  • 132
  • 133
  • 134
  • 135
  • 136
  • 137
  • 138
  • 139
  • 140
  • 141
  • 142
  • 143
  • 144
  • 145
  • 146
  • 147
  • 148
  • 149
  • 150
  • 151
  • 152
  • 153
  • 154
  • 155
  • 156
  • 157
  • 158
  • 159
  • 160
  • 161
  • 162
  • 163
  • 164
  • 165
2.3.2 System Reset Circuit
Control circuits IC1 and IC2 are initialized when a
RESET signal (LOW level) is output from port 1 (VOUT)
of IC10. IC10 monitors the +5 V line on port 3, and resets under the following conditions:
1.
When the power supply is turned on, a
RESET signal is output.
RESET is canceled when the
+5 V line goes up to 4.2 V, and then 100 ms passes.
2.
When the +5 V line goes below +4.2 V, a
RESET signal is output.
RESET is canceled when the
+5
V line goes back up to 4.2 V and then 100 ms passes.
2.3.3 Printhead Driver Circuit
The standard voltage for the A/D converter is made in ZD1 and input to CPU port 78.
Based on this standard
voltage, the A/D converter in the CPU operates.
Port 74 monitors the +35 V line between R50 and R51 to
determine the printhead driver pulse width. Using the monitored voltage, the CPU converts the voltage to a
digital value and decides the printhead driver pulse width, and then transports the data to the gate array via
CPU port 15.
Based on the monitored voltage, the CPU decides the printing interval.
Port 73 monitors the
printhead temperature to protect the printhead.
If the temperature exceeds 95° C (213° F) , printing is
stopped.
1
2
3
4
5
VCC
(+5V line)
VOUT (RESET)
RESET
RESET
Power On
(v)
100ms
100ms
Figure 2-33 Reset Signal Output Timing
VOUT
MRES
VCC
GND
+5V
+5V
R47
1K
IC10
PST5920
C16
0.1U
IC1
IC2
TPM96C041AF
23
RESET
61
RESET
1
2
3
4
E05B24YA
Figure 2-32 Reset Circuite
CPU
Gate
Array
C19
ZD1
+35V
78
79
74
73
R51
R50
+35V
R49
Address
Data Line
37
44
~
28
~
21
Printhead
Drive
Signal
69
76~89
91~99
Printhead Drive Transistor
Q1~Q12, Q13~24
Print Head
HTMP
+
C9
+35V
+35V
31
15
Figure 2-34 Printhead Drive Circuit
Operation Principles
LQ-2070 Servcie Manual
2-24
Rev.A