Xerox DocuColor 12/DCCS50, Service Manual

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1/05
10-117 DocuColor 12/DCCS50
Development
Principles of Operation
Reissue
Developer Bias and Power Supply
The Developer Bias High Voltage Power Supply (PSHV-L1) provides a DC voltage with an AC
signal superimposed on it. This composite voltage is provided to the developer before it is pre-
sented to the Photoreceptor Drum to form the image. These voltages are derived from inter-
locked +24 VDC provided by the IOT Drive PWBA. The power supply’s DC output level is
typically in the range of -510 VDC to -560 VDC, but can be set over the range of -205 VDC and
-800 VDC. The AC component is 1.0 KV peak-to-peak with a frequency of 9 kHz. As shown in
Figure 4 , signals from the IOT Drive PWBA control the voltage of the DC component, the volt-
age of the AC component and the frequency of the AC component. Figure 3
shows the location
of the Developer Bias High Voltage Power Supply (PSHV-L1).
Figure 3 Developer Bias Block Diagram
As the AC component of the Developer Bias swings through its high negative values, toner is
driven from the Developer Roll to the image areas on the Photoreceptor. As the Bias swings
lower negative, excess toner is retrieved from the Photoreceptor.
A wire carries the Developer Bias voltage from the Developer Bias PWBA to a Bias Plate at the
front of the Developer Rotary Assembly. The center shaft of the Developer Roll makes direct
contact with the Bias Plate when the Developer Housing Assembly is in the development point.
This direct contact transfers the bias charge to the Developer Roll.
Developer Clutch
The Developer Clutch is a reversal-type clutch. When the clutch is de-energized, the Main
Motor through a gear meshing drives both the magnetic Developer Roll and the internal augers
in the Developer Housing. The internal augers mix the toner and carrier beads while the mag-
netic Developer Roll moves the developer (toner plus carrier) to the Photoreceptor Drum for
developing the latent image.
The drive from the Developer Clutch to the Developer Roll and augers occurs only when two
conditions are met: (1) the roll is in the development point, and (2) there is a latent electrostatic
image on the Photoreceptor Drum to be developed.
Toner Supply
The developer composition (toner and carrier beads) and how the carrier beads are reused in
this machine is different from other color machines. The developer that is supplied in the Toner
Cartridges consist of both toner and carrier beads mixed together. As the toner is used to
develop the electrostatic image, the carrier beads are recycled back into the developer to be
remix with new toner and carrier beads. New developer is added to the system as determined
by Process Controls using
ADC (Automatic Density Control) readings. As new developer is
being added to the toner supply system and as the carrier beads are recycled, excess waste
carrier beads can accumulate which needs to be siphoned off. The excess waste carrier beads
are disposed of to the Waste Carrier Bottle. This
Trickle System for developer supply (referred
to here as toner supply) is unique to this color machine.
Because the Develop Rotor has four Developer Assemblies that are not stationary, the system
suppling the developer to the Developer Assemblies is complex.
The four colors of developer are stored in individual Toner Cartridges. For each of the four col-
ors, the developer is moved from the Toner Cartridges to the Toner Cartridge Housing, through
the Conveyor Auger, to the Rotary Dispenser, out through the Rotary Auger and into the Devel-
oper Housing Assembly.
The following will explain this process in detail, starting with the Toner Cartridge Unit.
Toner Cartridge Unit
The Toner Cartridge Unit contains 4 Toner Cartridges and their motors. This unit can be
removed from the machine as one complete assembly. This Toner Cartridge Unit contains the
following components: (Refer to
Figure 4 .)
• 4 Toner Cartridges (one each for yellow, magenta, cyan and black)
• 4 Cartridge Motors
• 4 Toner Dispenser Motors
• 4 Toner Cartridge Housings
• 3 Conveyor Augers (Yellow does not use this auger)
• 4 Toner Sensors
• Associated drive gears