Radio Shack TRS-80 III User manual

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TRS-80 MODEL III
MODIFICATION KIT
FIRST INTERNAL DISK DRIVE
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CATALOG NUMBER 26-1162
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CUSTOM MANUFACTURED IN U.S.A. BY RADIO SHACKM ADIVISION OF TANDY CORPORATION

PARTS LIST
Description Quantity
Manufacturer's
Part Number Radio Shack
Part Number
Cable, Disk Ground
Cable, Disk I/O
Cable, 20 pos,45", FF
Cable,8pos, 8.5", FFC
Clip, RICHCO, LCBS-4R
Disk Drive
Fastex, 16402 -04
FDC Board
Mounting Bracket (left)
Mounting Bracket (right)
Power Harness, Disk DC
Power Supply
RF Shielding
Screw, #6 32 x1/2", PH
Screw, #6 x3/8", plasrite
Screw, #8- 32 x1/2", PH
Tab, Ground, PS Conn.
Washer, #8, flat
Washer, #8, flat
1
1
1
1
2
1
2
1
1
1
1
1
1
4
6
4
1
4
4
8709166
8709154
8459020
8459108
8559018
8790112
8559020
8858029
B71910S
8719105
8709183
8790021
8729041
8569039
8569047
8563078
8529019
8589017
8589016
AW2533
AW2535
AW2631
AW2632
AHC0071
AXX5019
AHC0073
AXX0510
ART3083
ART3086
AXX6005
ART3085
AH01 546
AHD1552
AHD2307
AHC0325
AHD8514
AHD8513
DISASSEMBLY
1. Remove all cables from the bottom and rear of the
Computer and position the Computer on its rear panel.
Remove the ten screws from the case bottom. Hold the
case together as you take out the last few screws.
2. Position the Computer upright and remove the #6 screw
and washer from the top of the back panel of the Case.
3. Carefully remove the Case Top, lifting straight up and
off to the left (if facing the video screen). Disconnect
all cables connecting the video assembly to the com-
puter and set the Case Top aside.
4. Remove all cables connecting the CPU Board (main DC
power harness, CRT wiring harness, keyboard and cassette
cables, and RS-232 inter-connect cable if used).
5. Remove the five screws fastening the CPU Board (two in
"upper right corner, three on bottom). Remove the small
Board Mount Support Bracket and its two screws from
atop the metal chassis bracket.
6. Make sure all cables to the CPU Board have been dis-
connected. To remove PC Board, press the small tabs on
the plastic spacer mounts (RICHCO clips) through the
mounting holes in the PCB and gently pull the CPU
Board off.

PROCEDURE
1. Install the two RICHCO clips (plastic spacer mounts) and
the two Fastex clips in their positions on the left-hand
side of the metal chassis bracket. See Figure 1
.
2. Install the FDC Board (with J4 upward) onto the plastic
RICHO clips and fasten the bottom part of the Board
using two #6 x3/8" screws.
3. Attach the appropriate connector of the Disk DC Power
Harness (see Figure 2) to J3 on the FDC Board.
6.
I
Note that two of the connectors on one end of the
Disk I/O cable has some pins missing and the connector
on the other end of the cable has all its pins in place.
Connect the end with all pins in place to J4 of the FDC
Board so that the cable is coming out away from the
metal chassis bracket.
Connect one end of the 45", 20 position FFC cable to
J2 on the FDC Board.
Make sure that all unconnected ends of the cablet are
placed over the metal chassis bracket. Replace the CPU
Board onto the plastic spacer mounts (RICHCO clips)
and fasten the bottom part of the Board and upper right
corner using five #6 x1/4" screws.
FIGURE 1. RICHCO AND FASTEX CLIP POSITIONING
TO fDC B0A8S
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FIGURE 2. DISK DC POWER HARNESS

7. Connect on« end of the 8S", eight position FFC cable to
JP1 Aon the CPU Board. Bend the cable so as to make it
flat (see Figure 3) and connect the other end to JP1 B.
the Disk Brackets. Don't forget to connect the R&232
inter-connect cable if used, or the FDC inter-connect
cable which connects to J7 on the CPU Board.
8. Reconnect cables to the CPU Board (main DC power
harness, CRT wiring harness, and cassette cables). Do not
connect the keyboard cables at this time. Lay it beside the
computer case so it will not be in the way when mounting
9. Attach the small Board Support Bracket to the metal
chassis bracket with two #6 x1/4" screws.
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FIGURE 3. EIGHT POSITION CABLE BETWEEN JP1A AND JP1B
10. Now find the left Disk Mounting Bracket (the taller of the
two brackets) and install the RF shield around the Bracket
as shown in Figure 4. Bend the tabs around the rear of the
Bracket to hold the shield in place.
11. Attach the Disk Mounting Brackets to the Case Bottom
»(stubby rests positioned inward) using four #8 flat washers
(two for each bracket).
12. Position the Keyboard cable between the two brackets
and connect it to the CPU Board.
FIGURE 4. LEFT DISK BRACKET
WITH SHIELD

13. Attach the large connector of the Disk DC Power Harness
to J2 on the Disk Drive PC Board
,
14. Find the Disk Ground Cable and notice that one end has
two connectors close together. This is the Disk Drive end.
Connect the end connector on the Disk Drive end to the
grounding tab on the disk drive chassis. Attach the other
end of the ground cable to the main ground tab to the left
on the metal chassis bracket.
15. Attach the bottom connector of the Disk I/O cable to
the Disk Drive PC Board (J1). The other connector will
remain unattached.
16. Position the Disk Drive in the bottom position between
the Mounting Brackets and fasten the Drive using four
#8 x1/2" screws and four #8 flat washers. Be careful
not to tighten the screws too tight. Refer to Figure 5.
17. Position the Disk Power Supply (with power connectors
SK-2, 3, and 4positioned upward) on the left Disk
Mounting Bracket. Fasten using four #6 x1/2" screws and
four #6 washers. Refer to Figure 5.
NOTE: The ground lug must be installed underneath the
Board when the screw is intalled in the lower right-hand
position (at the ground symbol).
18. Attach the two connectors of the Disk DC Power Harness
to SK2 and SK3 on the Power Supply Board.
19. Connect the middle connector of the Disk Ground Cable
to the ground tab on the lower right of the Power Supply.
20. Connect the unattached connector of the AC Power
Harness to SK1 on the Power Supply Board.
FIGURE 5. DISK DRIVE AND DISK POWER SUPPLY
IN POSITION

21
.
Use apair of large dykes to cut the bottom position insert
in the Case Top as illustrated in Figure 6~ After the insert
is cut loose, remove it by pushing on it from outside of
the case. Trim off the rough edges around the opening.
22. Check back over your work and see that all cables are
properly connected. Reconnect the video unit and power
up the Computer. Check the unit's operation. After
unit is proved working correctly, turn power switch off
and disconnect the AC line cord.
23. Carefully place the Case Top over the Case Bottom.
Do not hit the CRT neck. It could implode or break off.
Install the #8 screw and flat washer in the top of the rear
panel of the Case Top.
24. Carefully rest the Computer on its rear panel and replace
'. the five 1" sheet metal screws twoard the rear, three 7/8"
!machine screws along the front, and two 1" machine
screws in the remaining positions.
25. Don't forget to put on the authorized Radio Shack seal
to maintain the warranty.
CUT THIS INSERT WHERE
INDICATED
CASE TOP
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FIGURE 6CASE BEZEL (shown looking inside Case with Cass Top upside down)

RADIO SHACK MADIVISION OF TANDY CORPORATION
,U.S.A.: FORT WORTH, TEXAS76102
CANADA: BARRIE, ONTARIO L4M 4W5
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TANDY CORPORATION
AUSTRALIA 'BELGIUM U. K.
230-316 VICTORIA ROAD PARC INOUSTRIEL OE NANINNE 8ILST0N R0A0 WEONESBURY
RYOALMERE. NSW 2116 §140 NANINNE WEST MiOLANOS WS10 7JN
12/80 PRINTED IN U.S.A.