Radio Shack TRS-80 PT-210 User manual

CONTENTS
Page
Introduction .......................................................................... 1
Specifications .......................................................................... 2
...............................................................................
General 4
Description
of Function .................................................................. 7
.......................................................................
Modem Interface 12
.....................................................
Description Keyboard Interface Circuit 18
........................................
Power Slupply and Power Supply Protective Circuits 19
................................................
Operational Description of the Control Unit 20
..............................................................
RS-232C Interface (Option) 33
Block Diagram
......................................................................... 36
MaintenanceProcedure
................................................................. 37
................................................................
Disassembly Instructions 38
Components
........................................................................... 38
Disassembly of PT-210 Portable Data Terminal
.............................................39
..................................................
Replacement and Adjustment within PCB 47
................................................................
Description of Assembly 47
Replacement ........................................................................... 47
............................................................................
Adjustment 54
Troubleshooting
........................................................................ 59
....................................................
Problems at Power-ON (Restore) Time 59
..................................................................
Problems in Operation 60
...................................................................
Printed Circuit Boards 64
........................................................................
Wiring Diagram 70
.............................................................................
Parts Lists 71
........................................................................
ExplodedViews 83
....................................................................
Schematic Diagrams 86

Introduction
Model PT-210 is a Portable Data Terminal that combines a thermal printer, a keyboard, and an acoustic
coupler. Electronic circuits are used for its control; its main control comes from a one-chip microcomputer
(hereinafterabbreviated as pCPU).
Separate units are provided for different functions. Pulse motors and solenoid are used as drive sources
for mechanicals. Simplificationis achieved by minimizing the number of mechanical parts, Accordingly, the
number of points which require adjustment is extremely small and maintenance is easy.
Other units also incorporate electronics. Electronic circuits are simplified for improving reliability and
stability, and the number of parts is minimized.

I / Specification
Data Transmission
.......................
Communication method Start-Stop Asynchronous
.........................
Communicationspeed 110/300bps; Switch selectable
110bps (11bit/character)
300 bps
d Obitlcharacter)
.........................
Communication mode Half/Fullduplex; Switch selectable
ASCII for Information Interchange
...................................
Line status On line/Off line; Switch selectable
................................
Line buffer.. .48characters; On received
....................................
Interface. Acoustic coupling
RS232C (Optional) (CAT. No. 76-1002)
.......................................
Parity. Odd., Even, Ignore; User selectable
....................................
Keyboard Matrix full keyboard
99 codes generated
67 printablecharacters
32 control characters
Printer
.....................................
Method. Non-impact, thermal-paper printing
..................................
Head life.. .20million word
......................................
Paper. .8-
1 /2" (1 00 ft) (CAT. No. 76-1003)
.............................
Character size.. .2.7 mm
X 2.0 mm (7 X 5 dot-matrix)
................................
Line length.. .8inches
10character per inch
80character per line
...............................
Line spacing.. .6lines per inch
Printing rate 50 characters per second; except CR time
.......................................
CR/LF Automatic at column 81
; no code is transmitted
....................................
CR time .0.80 seconds (OFF LINE)
0.86 seconds <ONLINE)
...................................
LF time.. .0.05 seconds (single step)
0.03 seconds (continuous step)
Acoustic Coupler
.................................
Compatibility Bell System 103A (equivalent)
Telephone (CAT No. 43-301)
.......................................
Mode. Oriainate
..................................
Modulation. Frequency shift keying (FSK)
..........................
Receive Frequencies. Originate
Mark 2225
Hz
Space 2025 Hz
.......................
Transmitter Frequencies. Originate
Mark 1270Hz
Space 1070Hz

Receive Sensitivity ............................ - 35 dBm
Transmit Power.
.............................. - 15 dBm
Â
(within 15 dBm difference between transmit level and
receive level)
I
Physical
Size (overall) ................................. 15.7" X
14.6" X 4.9"
(40.0 cm
X 37.2 cm X 12.5 cm)
Weight (Overall)
.............................. 15.0 pounds (6.8 kg)
Power Requirements
Voltage. ..................................... 105 through 1 35 volts
Frequency..
................................. .47 through 63 Hz
Power (Overall)
............................... 75 watts maximum
Environment
Temperature ................................. Operating 50° to 95OF (10° to 35OC)
Storage 40° to 104OF (-4O0C to 71OC)
(not including paper)
40° to 1OZ° (-40"C to 40°C
(including paper)
Humidity.
.................................... Operating 10%to 80% (no condensation)
Storage 10%to 90% (no condensation)

Duplex
Line
Duplex
(OptionalCat. No.
76-1002)
LOca' 1 Remarks
Network
-A
Electric Typewriter
Modem
Modem
I
Note: d) Keyboard : ASCII ..... 99 codes generated.
@ Printer: Non-impact, thermal-paperprintingfive by seven, 80 characters per line.
@ Acoustic Coupler: Compatibility ..... Bellsystem 103A (orequivalent).
(?) Self Test: Turning Power on while holding REPT key starts self test.
(MODES.W-HALF, SPEED S.W-300)
All printablecharacters are printed. Self test ends byturning power off.

MODEL PT-210 COMMUNICATION DIAGRAM
OFF-LINE
IÑÑÑÑÑÑÑÑÑÃ
I
1
1 KEYBOARD CONTROL PRINTER !
1 use as electric typewriter.
I I
I
I
1
Either Transmit or Receive at one
time
I
' KEYBOARD CONTROL PRINTER 1
I-
COMPUTER
1
I
I
I
I.
1 ACOUSTIC 1
I COUPLER 1 MODEM
1 KEYBOARD CONTROL PRINTER 1
1 Transmit and Receive at same time
I
I I
*
r---
I
'
I
L----
' I
-I--------
I
I
-
Telephone-
-
I
I
I
I
I
- --
COMPUTER
LÑÑÑÑ --- -- -- -- ÑÑ
Line
b
ON-LINE
I
I
I
I
RS-232C INTERFACE (OPTIONAL)
! KEYBOARD CONTROL PRINTER 1
ACOUSTIC 1
COUPLER
I
MODEM
Figure 2.
6
1
_^ 1
I
Telephone-
-
!------- --___ ------ J Line

* Character print
One character is composed of the 7
X 5 matrix dots. Assume letter "H" is to be printed. When Carriage
Return and data
"H" signals reach the printer, the line feed motor runs and the thermal head is caused
to move in the direction indicated in the figure on the left.
When the thermal head moves and the row of dots reaches position A, alt dots (1
- 7) are heated and
(
the color. of the paper is changed. When the thermal head advances to position B, only dot (4) is
heated. Identically, as the thermal head advances and the row of dots reaches positions C,
D, and E,
dots (41, (4) and (1 - 7) are heated, and pattern "H" is printed on the printing paper.
Direction of movement of the thermal head
:>
A = E/print
1 uaam
2IUDOI
31nna1
411111
51nnnm
6innaI
71nou1
Figure 5.
The relationship between thermal head feed and dot printing positions is as shown below. (Since con-
trol signals are controlled by the pCPU,
it is not possible to make adjustment.)
1 Character
Carriage Return
Motor
Thermal Head
Figure 6.
8