Head Driver - Tally Dascom 7010 Series Maintenance Manual

(2) Head driver

The head driver is incorporated in the Unit, Head.
During printing, pin 116 (HDVON) of U14 (Custom IC) goes to "High", and Q2 and Q1 turn ON.
Thus +24V is supplied to the thermal head (Unit, Head).
The print data is sent from U14 (Custom IC) to the head driver in the thermal head.
The signals HD1 to 4, HDSTB, HDCLK and HDLAT (pins 109 to 113, 108, 115 and 107 of U14)
are sent to the thermal head.
According to the print data (HD1 to 4), the selected thermal elements are heated and the
melted ink makes dots on media (or dots are printed on thermal transfer paper).
The width of heating pulse applied to a thermal element varies with the head temperature to
keep the printing density constant.
U14
Custom IC
Head supply voltage ON/OFF
116
HDVON
HDVON
117
HCVON
HCVON
Thermal element abnormality check ON
109-113
HDATA1-4
108
HDSTB
115
HDCLK
107 HDLAT
HDLTH
R94
Q2
DTC114EM
Q29
DTC114EM
When driving: +24V
When checking: +3.3V
U15A
HD1-4
2,4,6,8
A1-4
HDSTB
11
A5
13
HDCLK
A6
16
A7
1,19
OE
74HCT244
+24V
R93
Q1
2SJ505S
+3.3V
VHEAD
Thermal element abnormality check
Q3
DTA114EM
R99
D2
+5V
18,16,
HEADD1-4
14,12
Y1-4
HEADSTB
9
Y5
R101
7
Y6
5
Y7
2-33
2-2. Operation of Control Parts
Head power supply monitoring
+3.3V
D1
R96
R95 VHEADMON
C61
R97
R100
HEADRES
C62
J3
13
HDTHM1
1-4,26-30
10,12,14,17
9,15
HEADCLK 16
18
HEADLAT
11
5-8,21-25
[Main PCB]
U1 CPU
9
ANI4
10
ANI5
Thermal
Head