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M
G
OTOR AND
EAR
To remove motor and gear train assembly:
a) Remove top cover assembly (see para 2.1).
b) Remove belt and styli assembly and idler pulley (see para 3.1).
c) Remove the drive pulley by pulling it upwards (its shaft is a push fit in the large spur gear within
the base frame).
d) Prise the wormshaft out of its supports, and remove it.
e) Prise the bevel pinion from the motor shaft, and remove the spacer from the shaft (if fitted).
f) Unsolder the wires from the motor terminals.
g) Remove the two screws securing the motor to its mounting, and withdraw the motor.
NOTE: On earlier printers, the motor is lightly glued to its mounting, and it will be necessary to prise them
apart carefully.
To install motor and gear train assembly:
Prior to installing the motor, determine whether the base frame is of the early pattern or the later design.
On the early pattern, there is a cross-shaped slot in the motor mounting flange; the later design has a
vertical slot only.
a) If the printer is of the early type, apply a thin coat of suitable glue, such as Loctite, to the face of
the motor.
b) (b) Position the motor on its mounting flange with the orientation mark (on the terminal end of
the motor) at the outside, and insert the two attachment screws. If the printer is of the later
design, the screws may be tightened fully at this stage. If the printer is of the earlier pattern, the
vertical height of the motor must be set as shown in Figure 4; it may be advantageous to
manufacture the jig shown in Figure 4 to ensure accurate setting of the motor before the screws
are tightened.
c) Fit the spacer to the motor shaft, and push the bevel pinion fully on to the shaft.
NOTE: On some motors, the end bearing is recessed on its outer face. The spacer for use with this
motor is 3.25 mm long, whereas the spacer for use with the flush-faced end bearing is 2.92 mm
long. It is essential to ensure that the correct spacer is fitted.
If a spacer is not available, set the bevel pinion clearance as shown in Figure 4.
d) Solder the wires to the motor terminals - the red wire connects to the outer terminal, the black
wire to the inner terminal. Ensure that capacitor C9 is connected across the motor terminals.
NOTE: The black wire must pass over the white wire which connects to the conductor strip in the
top cover.
12
Sinclair ZX Spectrum Service Manual
Spectrum For Everyone https://spectrumforeveryone.com/
T
A
RAIN
SSEMBLY
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