SHARP SP1581R Technical Report

COPIER : Z-88

CHANGES IN THE MAIN PWB

1. PREVENTING IRREGULAR NOISE GENERATION BY A SCAN MOTOR ERROR

2. PREVENTING IRREGULAR NOISE AND RADIO INTERFERENCE OCCURRENCE THAT
CAUSED BY A MAIN MOTOR ERROR

Correction the missprint in the technical report SP-1581.

1.Model name: Z-88/SF-2010.

REVISED

Date: Oct. 5, 1993
No. : SP-1581 (R)

2.General: To abate mechanical noise generated when the main motor is in operation and when
the scan motor is operating for return, some parts within the main PWB are added and
removed with a change in the CPU.

3.Phenomenon: 1. While the scan motor is reversing, its speed becomes faster then normal that hits the

paper exit side optical frame and may generate a knocking sound, therefore.

2. The main motor continues to run faster when the power is turned on.

4.Cause: 1. Owing to a lack of circuit operational margin in the circuit to detect the FG signal from

the main motor, it makes the motor to rotate faster that disables to detect the FG signal.
This causes it to return in a full power and hits with the optical frame when it stops at
the home position.

2. Counter-locomotive voltage of the main motor employed to control FET power

transistor exceeds the voltage withstanding point and damages the transistor and
makes it conductive. Although a high speed diode is used to absorb the
counter-locomotive voltage, it disables to absorb it even with this diode.

5.Description: 1. Scan motor irregular mechanical noise generation

Both the R27 resistor and the C24 capacitor of the main PWB are changed.

2. Preventing main motor control components from damage.

The diode D3 of the main PWB is removed with a capacitor newly added.

• Resistor R27 changed from 3.3KΩ to 5.1KΩ.

VRS-TS2AD332J VRS-TS2AD512J

• Capacitor C24 changed from 22,000pF to 5.600pF.

VCKYTVIHF223Z VCKYTVHB562K

• Diode (D3) replaced by a capacitor

VHDISR124200A (Q’ty: 2 to 1) VCQYNA2AM437K (Q’ty: 1)

Note: Both D3 and D4 diodes are used but only D3 diodes have been replaced by

capacitors.

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SHARP CORPORATION Reprography Division

Green

C

Besides, change is made to the CPU for the main motor control frequency.

• Change in the CPU (main motor control frequency)

4KHz 16KHz
VHI78011GC520 VHI78011GC526
VHI78011GC524

• R14 changed (4.7KΩ to 560KΩ) to abate radio interference and the use of a ferrite

core (for 100V series machine only).

VRS-TS2AD472J (Quantity: 4 to 3)
VRS-TS2AD561J (Quantity: 1 to 2)
RCORF0012FCZZ (Quantity: 1) for the 100V series machine only.

* CPU of the main PWB had been changed to VHI78011GC525 since the first

production unit must be order placed under the parts code of VHI78011GC526.

Chronological changed in the CPU and the main PWB

1st lot

AB series

CPU

Main
PWB

VHI78011GC520
inch series
VHI78011GC504

AB series
CPWBS0955FC53
inch series
CPWBS0955FC51

*1: CPWBS0955FC57 has R27 and C24 changed and the D3 replaced by a capacitor

from CPWBS0955FC55.

*2: Changed since the first production unit for the SEEG version with others made

running change from mid-March 1993.

6.Action: (Factory action)

SEEG: Since the first production unit.
Others: Running change since mid-March 1993.

From Dec/92
production unit for
all destination
excluding SEEG

All destinations,
excluding SEEG.
VHI78011GC525
(Mask CPU)

All destinations,
excluding SEEG.
CPWBS0955FC55

From
mid-December
1992 except for
SEEG.

*1
CPWBS0955FC57*2CPWBS0955FC58

Running change
from mid-March

1993.

*1
VHI78011GC526
(Mask CPU)

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