Troubleshooting; Print Quality - Samsung ML-920 Service Manual

4-7 Troubleshooting

4-7-1 Print Quality

Error Status
Vertical black line and
band
Digital Printer
Digital Printer
Digital Printer
Digital Printer
Digital Printer
Vertical white line
Digital Printer
Digital Printer
Digital Printer
Digital Printer
Digital Printer
No image
Digital Printer
Digital Printer
Digital Printer
Digital Printer
Digital Printer
Light image
Digital Printer
Digital Printer
Digital Printer
Digital Printer
Digital Printer
Dark image
Digital Printer
Digital Printer
Samsung Electronics
Check
1. Bad blade of Toner cartridge
2. LSU
1. LSU window contamination
2. Toner cartridge
1. Seal tape is removed?
2. GND OPC is well grounded?
3. LSU running well?
4. Biss voltage is normal?
5. Lower toner?
6. Is there video data from Main PBA
1. Check seal tape removing
2. LSU light power normal?
3. Enough toner?
4. High charger voltage?
5. Lower bias voltage
6. Contamination of high voltage contact.
7. Transfer volatge and roller.
1. LSU light power normal?
2. Bias voltage output is high?
3. Video data is always supplied?
Solution
1. Change Toner cartridge
2. Replace LSU
1. Clean LSU window
2. If not LSU, change Toner cartridge.
1. Removing seal tipe
2. Measure the resistance between frame
ground and the ground spring attached
frame. Confirm stable ground. Unless bad
ground, detach cabinet, check where is bad
point
3.Adjust LSU or replace it
4. Normal Dev bias = -350V
5. Shake toner cartridge and print.If a liitke
good, toner is empty
6. Test engine test pattern , replace Main PBA
1. Check and remove tape
2. LSU light power check is difficult.
Compare with new one and check.
3. Check toner and developer counter
4~5. Measure all high voltage output.
6. Leakage toner cause bad contact and
increase contact resistance. Clean contami-
nated area.
1. Check the rated level and replace.
2. Set to power rating.
3. Replace defected board.
Troubleshooting
4-15