Radio Shack TRS-80 User manual

•
erv1ce
TRS·BD®
DT-1
Catalog Number 26-6050
CUSTOM MANUFACTURED IN U.S.A. BY RADIO SHACK, A DIVISION OF TANDY CORPORATION

TRS-80® DT-1
Manual
© 1982 Tandy Corporation
All Rights Reserved
Reproduction or use, without express written permission
from Tandy Corporation,
of any portion of this manual is
prohibited. While reasonable efforts have been taken in
the
preparation of this manual to assure its accuracy, Tandy
Corporation assumes no liability resulting from any errors or
omissions in this manual, or from the use
of the information
obtained herein.

-----------TRS-BO ® -----------
TRS-8S DT-1 Service Manual
26-6SSS
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___ .....,D-.T_- ... 1 ________ TRS-BO ® __ .....:i;;S~e.;:;.r.:.v.:.i~c~e~M~a;,;,,:;no=u .. a_1 ____ _
Table of Contents
l/Specifications •••••••••••••••••••••••••••••••••••• 5
2/Dissassembly Instructions ••••••••••••••••••••••••• ?
3/Troubleshooting Chart ••••••••••••••••••••••••••••• 11
4/Pr inted Circuit Board Layout •••••••••••••••••••••• 15
5/Parts List . ............................. . ........ . 17
6/Schematic Diagram ................................. 21
7/Theory of Operation ••••••••••••••••••••••••••••••• 25
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DT-1
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___ ...... D ... T._- .. 1..... _______ TRS-BO ® __ ...... s ... e.r ... v ... i ... c ... e...,..M .... a ... n_u_a_1 ____ _
1/ Specifications
AC Power Supply
Power Requirements
Power Consumption
Temperature Range
Humidity Range
non-condensing
Size
Weight
1~5-13~ VAC, 6~ Hz
2~ watts
55 to 11~ F
(13 to 43 C)
1~% to 8~% relative
18.5" x 12" x 21"
Cl7cm x 31 cm x 53cm)
23.4 lbs (l~.5kg)
RS-232-C Input/Output
============================================================
Signal Function Pin #
=============================================================
PG
Protective Ground
1
TD
Transmit
Data 2
RD
Receive Data
3
RTS Request to Send 4
CTS Clear to Send
5
DSR Data Set Ready
6
SG
Signal Ground
7
CD Carrier Detect
8
DTR Data Terminal
Ready
2~
============================================================
Table 1.
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---
0
-T---
1
-------TRS-BO ®
Service Manual
RS-232-C Serial Printer
============================================================
Signal Function
Pin #
====:========================================================
PG Protective Ground 1
TD Transmit Data
.,
.J
CTS Clear to Send 5
DSR Data Set Ready
6
SG
Signal Ground 7
CD Carrier Detect
8
DTR Data Terminal Ready
2~
============================================================
Table 2.
Parallel Printer Interface
========================================== = ===============
Signal Function
Pin
#
== = =======================================================
Strobe Clock the data from the 1
processor
to
the printer
Data
~
Bit
~
LSB
of output data byte
3
Data
1
Bit 1 of output data byte
5
Data
2 Bit
2
of
output data byte 7
Data
3
Bit
3
of output data byte
9
Data
4
Bit 4 of output data byte 11
Data
5
Bit
5 of output data byte 13
Data
6
Bit
6
of output data byte 15
Data
7 Bit 7 of
output data byte
(MSB)
17
BUSY Input
to Termnal
from Printer
21
High
indicaGes busy
===========================================================
Table
3.
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________ D_T_-_1 _________________ "TFISi-E3CJ ® ____ __.s.e_r_v_i_c_e,__M_a_n_u_a_1 ______ __
2/Dissassembly Instructions
i. Turn the DT-1 upside down on your work area.
2. Remove the 6 screws from the bottom.
3. Rotate the DT-1 rightside up. You must hold the top
and bottom section together during this operation.
Leave room to the left for the top to rest.
4. Lift off the top section and lay it on its side to the
left of the bottom section. The unit may be operated
in this position for test purposes.
Further Dissassembly
If desired the top section may be separated from the bottom
section. To do this unplug the cable from the edge
connector and the grounding lead from the spade lug ground
connector on the Video Board. The top and bottom sections
are now separate.
Circuit Board Removal
Follow these steps to remove the circuit board from the
bottom section of the DT-1:
1. Unplug the cables going to the video board, the power
supply and the keyboard.
2. Remove the 6 nuts and washers holding the circuit board
to the bottom section.
3. Unplug the power indicator cable going to the keyboard
from the main circuit board.
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_______ D_T_-_1----------------"T~!S-EICJ® _____ s_e_r_v_1_·c.e.....,M_a_n_u_a_1 ______ __
CRT Removal.
Be very careful removing the CRT. It is fragile, and could
be dangerous if broken. Never hold it by the neck. Follow
the steps below.
1. Remove the plug from the end of the neck. Gently pull
straight back. Be careful not to bend the pins. Check
to be sure you haven't shorted terminals or components
mounted on the plug.
2. Remove the yoke from the neck by loosening the clamping
screw, then pulling the yoke straight back. Be careful
to avoid the pins at the end of the neck of the CRT.
3. To remove the anode lead, loosen the plastic insulating
cover from the CRT, then remove the lead by pressing to
one side on the connector while gently lifting up on
the other.
4. Remove the 2 screws holding the video board to the top
section and set the board to one side to allow access
to the CRT mounting studs.
4. Remove the 4 nuts and washers from the mounting studs
at each corner of the mask.
5. Supporting the CRT from the body (not the neck) lift it
up and back off the studs. Lay it on a soft cloth face
down.
6. Finally unhook the spring and the two loops of braid
from the corners of the CRT.
Keyboard Removal
To remove the keyboard,
1. Take out the 6 screws that hold the mask to the bottom
section.
2. Lift off the mask and the keyboard.
3. Unplug the ribbon cable going to the main circuit board
and the grounding spade lug from the left end of the
keyboard. See Figure 1.
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