Sharp SF-2050 Service Manual page 71

C. Charger current check
Check only the difference (balance) in the drum currents in the front
frame side and the rear frame side.
1
Perform procedures (3)-B-1 to 5.
2
Clean the main charge saw teeth plate, and install the main
charger unit to the copier.
(Do not install the transfer/separation charger.) Manually turn on
the door switch.
3
Check the drum current in the front frame side and the rear frame
side. The difference between the two currents must be within
10µA.
a. Turn on the main switch, and execute simulation 8-08. (MGVG is
turned on for 30 sec.)
b. Measure the drum current in the front side and the rear side.
•
When the microswitch is OFF, the drum current in the front
frame side is displayed.
•
When the microswitch is ON, the drum current in the rear
frame side is displayed.
(OFF)
N/C
N/O COM
c. Check that the difference between the currents in the front and
the rear sides is within 10µA. If the difference is more than 10µA,
the charger unit is defective. Replace it with a new one.
D. Charger grid voltage adjustment
This adjustment is performed without using the electrode sheet but
with the OPC drum.
1
Install the DV unit and the drum holder unit to the copier and turn
on the power of the copier. (In this case, the electrode sheet is not
used.)
2
Install the main charger unit to the copier. All charger units must
be installed to the copier.
GBNOM (Normal mode)
Set value: 385=727V output
To make the measured voltage smaller:
make the set value smaller. (1 step = 2V)
To make the measured voltage greater:
make the set value greater.
GBTS mode (TSM mode)
Set value: 330=622V output
To make the measured voltage smaller:
make the set value smaller. (1 step = 2V)
To make the measured voltage greater:
make the set value greater.
GBPOTO (Photo mode)
Set value: 338=450V output
To make the measured voltage smaller:
make the set value smaller. (1 step = 2V)
To make the measured voltage greater:
make the set value greater.
(ON)
N/C
N/O COM
(Measurement at the high voltage PWB check point)
3
Remove the rear cabinet.
4
Connect the grid voltage output check pin (GB) and the digital
multi meter.
5
Set the digital multi meter range to DCV range.
(Use a digital multi mater which is able to measure up to DC
1000V.)
6
Manually turn on the door switch.
7
Turn on the main switch and execute 8-02 (normal mode), 8-03
(photo mode), or 8-04 (TSM mode) to check.
8 – 5
TESTPOINTCP-GB Output voltage
–730 ± 5V
Normal mode 8-02
–625 ± 5V
TSM mode 8-04
–450 ± 5V
Photo mode 8-03
GB