Radio Shack TRS-80 Service Manual page 36

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• Solenoid drive circuit
\6W 0.56!"1
l ~ Kn
liO
Potr
tSOn
150fi
l..SKO
r--+--t--<'-i-,,_ _
__.._Q Solenoid!+)
T S
T7
!£On
The solenoid is driven
by
the PEN UP signal PBO and t he PEN
DOWN
signal PB! that is sent to the drive circuit via t he IjO port.
l) With high state of the PBJ signal, TS and 17 actuate t o turn the solenoid{- ) tem>inal GNO level. Act uation of the TS causes
T6 to actuate to turn the solenoid(+) tenninal VM level (about +6V) and drive the solenoid to lower tl1e pen to start printing.
2) With high state of the P1l0 signal, 12 and T4 actuate to t urn the solenoid ( +) tenninal GND level. Actuation of the T2 causes
T3 to actuate to turn the solenoid(- ) tem1inal YM level (about ,.6V) and drive the solenoid to lift up the pen to stop
printing.
3) DJ thru
05
are the arc suppressor diodes for the solenoid.
• Motor drive circuit
25
f>C.,
C»- -
Y motor 0
2.-.
P C S
1--""-"--·C»-- -
Y motor B
23
f•C5
1-"'-'"-{ :;»-- - Y
motor
C
1/ 0
port
22
r•c
<t :>o- -
Y motor A
21
J'(:
~
:>o- -
X motor 0
in
r•c.:2
19
l'CI
1 8
PCO
:>o--
X motor A
83sic drive puls.e
D
D
Ph3wA
Phase B
Phase C
Pho;c
o
Mo1or d ock
I• •I
!ti
in a.85m
s ..
-c
Do not sale this PDF !!!
X
mo1or
A tltru X
n101or
D are the signals th at drive the step
1notor
that
n1oves
t he carriage on the carriage rail. J \nd, Y motor /\ thru Y
1not or Dare the paper feed step motor drive signals.
As the PC.2 fetches character data from the
ROM
of the Printer, the
1uotor
drive
action is co1ltr0Ued via the
1/0
port of
the Printer.
D
I I
J_
Hold tirn(:
tMH
Min l 2tnStc
- 32-