Samsung SCX-4216F Service Manual page 35

SUMMARY OF PRODUCT
4.4.1 HVPS(High Voltage Power Supply)
1) Transfer High Voltage (THV+)
- Function: Voltage to transfer developed toner on OPC drum to a paper.
- Output voltage: Maximum +5.0KV ±5% (Duty changeable, unload)
- 1.0KV ±15%(When cleaning, 200MOhm)
- Error: If THV (+) doesn't output, a ghost status (same character is printed after one cycle (76mm)
of OPC) with a low density occurs due to a toner on OPC drum cannot normally transfer to a
paper.
2) Charge Voltage (MHV)
- Function: It is a voltage to charge entire surface of OPC with -900V ~ -1000V.
- Output voltage: -1.3KV ~ 1.8KV DC ±50V
- Error: If MHV doesn't output, a black paper is printed out because toner on developing roller
moves to OPC drum due to the surface of OPC not being charged.
3)Cleaning Voltage (THV-)
- Function: It removes a dirty on a surface by sending a minus toner in a transfer roller to an OPC
drum to recover toners.
- Output Voltage: There is no feedback control, so change range of output is big up to load.
- Error: Toner contamination occurs at the backside of a printed-paper.
4) Developing Voltage (DEV)
- Function: It is a voltage to develop a toner with using a difference of electronic potential on an
exposed part by LSU (Laser Scanning Unit).
* Generally, the electronic potential of exposed OPC is -180V and exposed developer is -350V
when printing, so toner with minus (-) is developed on an exposed part.
- Output voltage: -200V ~ 600V DC ±20V
- Error: 1. If DEV is GND, a density is going significantly down.
2. If DEV is floating due to instable contacting point of terminal, and etc., a density is signif-
icantly going up.
5) Supply Voltage(SUP)
- Function: It is a voltage to supply toner to a developing roller.
- Output voltage: : -400V ~ 800V DC °æ 50V(Use ZENER, DEV gear)
- Error: 1. If SUP is GND, a density is dramatically going down.
2. If SUP is floating due to instable contacting point of terminal, and etc., a density is signif-
icantly going down as much as it cannot be recognized with eyes.
Service Manual
4-14
Samsung Electronics