SMPS AND HVPS
B273 6-12 SM
6.4.1 HVPS
The HVPS supplies the following voltages to the machine:
Transfer High Voltage (THV+):
This voltage transfers toner from the OPC drum to the paper.
• Output voltage: +1300V DC ±20V
• Failure Symptom: Low-density printing occurs due to toner on the OPC drum
that was not transferred to the paper due to THV (+) not present. If this
condition persists, waste toner over-flow can occur. Ghost images may
appear which repeat at 76mm intervals.
Charge Voltage (MHV)
This voltage charges the surface of the OPC from –900V to –1000V.
• Output voltage: –1550V DC ± 50V
• Failure Symptom: Toner particles are transferred to the whole OPC drum
surface if MHV is not present due to the OPC drum surface having no
charge. In this condition, a black page is printed out.
Cleaning Voltage (THV-):
This voltage removes toner contamination from the rear-side of the paper by
sending negative polarity to the transfer roller. This forces toner to transfer back to
the to OPC drum.
• Output Voltage: –1200V, +300V/–150V
• Failure Symptom: Smudges and toner contamination appear on the reverse
side of the printed page.
Developing Voltage (DEV):
This voltage develops the toner on the section of the OPC drum surface exposed
by the LSU.
At printing, the exposed voltage on the OPC is –180V. Unexposed voltage is –900
to –1000V. The exposing voltage on the DEV is –430V. Therefore, toner with
negative polarity is developed onto an exposed section of the OPC.
• Output voltage –430V DC ± 20V
• Failure Symptom:
• Print density becomes extremely light if DEV is GND.
• Print density becomes extremely dark when DEV is “floating”, due to poor
connection between the frame and cartridge contacts, etc.
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