Epson Stylus Color 760, Service Manual

Page: 32 / 172

EPSON Stylus COLOR 760 Revision C
Operating Principles Overview 32
2.1.1.4 Platen Gap (PG) Adjust Mechanism
The PG adjustment, at the right of the printer mechanism, consists of the PG
lever, PG support lever, right/left parallelism adjustment levers, and CR guide
shaft.
The PG adjustment mechanism is designed to keep the platen gap correct for
the paper thickness to prevent ink from smearing. The PG support lever joins
the CR guide shaft, which has and eccentricity via PG support lever. Switching
the lever from “0” to “+” rotates the CR shaft and changes the platen gap from
narrow to wide.
Table 2-3.
Platen Gap Adjust Lever Setting
2.1.1.5 Paper Feeding Mechanism
The paper feeding mechanism transports paper loaded from ASF using the PF
rollers and paper eject rollers. A new type of DC motor is used for the PF
motor. See the table below for the DC motor specifications.
Table 2-4. PF Motor Specifications
Unlike a stepping motor, the DC motor that drives the paper feeding
mechanism can not measure the paper feeding amount by referring to the
pulses given. For this reason, the loop scale and encoder sensor are directly
attached to the left end of the PF roller shaft to mechanically control paper feed
amount. See Section 2.2 for detailed information on the PF motor control
circuit.
Drive from the PF motor is sent to the PF rollers and paper eject rollers as
described below.
o
To the PF rollers:
PF motor pinion gear (CCW rotation)
→
Spur gear (76)
→
PF rollers
o
To the eject rollers:
PF motor pinion gear (CCW rotation)
→
Spur gear (76)
→
Combination gear
(13.5, 308)
→
Spur gear (28)
→
Paper eject rollers
NOTE: Above CCW rotation is mentioned viewing from the PF motor pinion gear
side.
Figure 2-6 in the next page gives the paper feeding mechanism block diagram,
showing the parts along the PF motor drive transmission paths.
Paper Lever Position PG adjustment value
All Media Front
0 mm
(1.14mm between head and platen)
If you find any print
problems or you
use thick paper
Rear
0.7mm
(1.84mm between head and platen)
Item Description
Motor type DC Motor with Brush
Drive voltage +42V +/- 5% (DRV IC voltage)
Coil Resistance 31.1 ohm +/- 25%
Drive frequency [Hz] 26.6mH +/- 25%
Control method A3958