Case; Internal Rear Mounting Plate; Front Bezel; Top Cover/Power Supply - Radio Shack TRS-80 Service Manual

DISASSEMBLY/ ASSEMBLY
3.1 OVERVIEW AND CASE
The Model4P is modular in construction in that it can be disas-
sembled in major component blocks after removal of the case
cover. These major component blocks include the disk drives,
the power supply, main CPU board, the CRT display, and the
monitor board. Accessory components such as the power cord,
additional diskettes, and operating manual can be stored in
convenient recesses in the removable front cover/base. This
cover/base provides protection for the CRT and disk drives dur-
ing transport. It also serves as the base in the non-operating po-
sition of the computer.
The cover/base is held in place with snap locks on each side.
These locks are positive action with a protective boss to pre-
vent accidental opening of the cover/base. To remove, merely
unsnap the lock and release the catch from the main assembly
latch. The following procedures are noted in sequential order
required to provide access to some of the components. Some
parts removal does not require previous steps. Those which do
are noted. For reassembly of unit, reverse order of disassembly
instructions.
1. The main assembiy of the Model 4P has a removable
cover which allows access to all internal components when
removed. Remove all connections to the rear of the unit.
These include the AC power cord, printer cable, I/O port
connector, and RS-232-C connector. The printer cable and
I/O port connectors are edge card type connectors - ex-
ercise care in their removal.
2. Place the unit Bezel/CRT face-down on a soft surtace to
prevent damage to the CRT.
3. The case is held in place with six screws. Remove two
screws from either side of the case at the front of the unit.
To gain access to the last two screws, press down on one
end of the carrying handle and then lift the handle from its
recess. The final two case mounting screws are accessible
under the handle assembly. These two screws attach the
handle assembly as well as the case to the ',nternal rear
mounting plate.
side of the unit. With the rear of the unit toward you, two of
these screws are located at the left just in front of the Disk
Drive Assembly and accessibie from the left side of the
chassis assembly. The two on the right are accessible from
the rear of the chassis assembly.
3. Six other screws are located around the outside edges of
the rear mounting plate. Remove the plate and set it aside
for reassembly.
3.3 FRONT BEZEL
1. The front bezel can be removed from the unit after the case
and rear mounting plate have been removed as noted in
Paragraphs 3.1 and 3.2.
2. Pull the brightness and contrast knobs off the pots from the
front.
3. The rear mounting plate removal allows access to the six
bezel·mounting screws. Four screws attach to the outside
flanges of the metal chassis. The other two screws are lo-
cated to the right of the metal partition separating the Disk
Drives from the CRT section of the unit. Access to these
two screws is with a long shank 1/4" nutdriver above and
below the fan assembly.
4. Once these six screws are removed, remove the bezel and
set it aside for reassembly. Exercise care in handling to
prevent scratching or marring the surface.
3.4 TOP COVER/POWER SUPPLY
1. The Power Supply for the Model 4P is located on the un-
derside of the top cover. Remove the case and rear ter-
minal plate as noted in Paragraphs 3.1 and 3.2.
SCREWS
4. After removing all six screws, lift the cover off the computer
and set it aside for reassembly. Exercise care to prevent
scratching or damaging the cover.
3.2 INTERNAL REAR MOUNTING PLATE
1.
Remove the case from the unit as noted in Paragraph 3.1
DISK
_-----rTI
DRIVE
ASSEMBLY
FAN
2. The rear mounting plate serves to provide mounting for the
case carrying handle and protection for the CRT. There are
ten mounting screws which attach this plate to the main
metal chassis of the computer. Four screws (Item 53 on
exploded view p. 144, two on each side) mount the handle
support (Item 16) and are accessible from the LH and RH
13
REAR VIEW
Figure 3-1. Bezel Mounting Screws