Date: Jun. 19, 1995
COPIER : Z-20
No. : SP-1885
REGARDING COPIES WITH BLANK AREAS
1.Model name: Z-20/25/27
2.General: Under conditions of high humidity, the CRU unitUs internal MC Charger may cause a
situation where a charge cannot be created on the drum. This causes blank areas on
copies as illustrated below.
[Malfunctioning state] Blank areas show up on the copy.
Front
Halftone
A blank, white area remains.
The blank area is typically not in
a straight line, and has varying width.
3.Description: In order to stabilize the discharge from the MC unit, please carry out the following repair.
(1)Make the high-voltage flow to the main circuit higher, and increase the electric supply
to the charger. (turning the setting volume (VR 201) to the right increases the supply)
(2)Change the high voltage resistance for the copy unit and increase the flow of
electricity.
Increase the resistance from 510 KΩ to 1.5 MΩ
(Supplementary Explanation)
The high voltage circuitUs electric current is used partly for the belt charger and
partly for the copy unit charger. The resistance for the copy unit charger is used to
adjust the flow of electricity in both parts. Making the resistance for the copy unit
charger higher also increases the flow of electricity in the belt charger.
SHARP CORPORATION Reprography Division
1/4
Green
C
Electric flow output (Io)
Belt charger flow (Im)
Main PWB
board high voltage
Copy charger
flow (It)
Please carry out these repairs for any units produced after Mar., 1995 which
malfunction in the way described above.
4.Procedure: (1)Remove the copy unit
➀ Take off the four screws connecting the
rack cover and remove the rack cover.
Rack cover
Copy unit
resistance
Copy
unit
charger
Belt
charger
➁ Take off the rack gear bracket. (Make sure
to pull the screws out in the right direction)
➂ Slide the copy unit over and remove the 3 screws attached to the Accuride.
➃ Slide the copy unit sideways and off of the frame.
(2) Remove the top cabinet
➀ Open the front door and take out the development cartridge.
➁ Remove the five screws holding the top cabinet in place.
➂ Pull the top cabinet up and off.
Top cabinet
2/4
Development cartridge
(3)Remove the 2 screws from the fan unit.
Motor pulley
Fan pulley
Fan unit
Idle pulley
High voltage volume control knob
(VR 201) - turn this to the right.
(4)There is a volume control knob on the circuit board on the bottom of the Fan Unit
(VR 201). Turn it clockwise gently until it stops.
(5)Put the fan unit back in place.
➀ Make sure the fan belt is correctly in place along the motor pulley, fan pulley and idle
pulley.
➁ Make sure the fan belt is not in contact with the fan case harness.
➂ Check that the idle pulley is turning smoothly by turning the main motor pulley by
hand.
(6)Change the copy resistance unit
High voltage separation
harness (White)
High voltage copy harness (Red)
High voltage separation resistance
High voltage copy resistance - change
to the values written below:
For use overseas : 1.5 MΩ (new value)
(7)Restore the top cabinet and copy unit to place
(8)Carry out a copy test. Check that halftone quality has improved and that there are
no blank areas on the copy.
If you have carried out the above repairs and there are still problems with blank areas
on copies, it may be that the teeth of the CRU unitUs MC charger have deteriorated,
that some external substance has contaminated the unit, or that some other problem
has occurred which has caused permanent damage. Please replace the MC charger.
3/4
5.Action: From 1995 mid-March production
MC charger unit
Remove all four screws.
A set of service parts.
Ref.
Model
No.
<Interchange>
1. Inte r cha ng eable. 4. Not i nt er changeable.
2. Current type can be used in place of new type.
New type cannot be used in place of current type.
3. Current type cannot be used in place of new type.
New type can be used in place of current type.
Parts marked with “ ” is important for maintaining the safety of the set. Be sure to replace these parts with
sp ec i fi e d on es for m ai n ta in ing the sa fe ty an d pe r fo r ma nce o f the set .
name
Z-20
Z-25
Z-27
Version P/G No.
7
All
2
!
Current parts New parts
Parts code Parts code
DUNT-6707FCZZ DUNT-6707FC12 AF
— CCASZ0258FC51 BA MC charger unit —
Price
5. Interchangeable if replaced with same types of
relate d parts in use .
6. Othe rs .
Parts name
rank
Resistor unit
(1.5MΩ)
Effec-
tive
time
Mid-
’95/3
Inter-
change-
ability
3
Note
4/4
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