Service manual

7.3.3 Belt Transfer Bias
The belt transfer charge unit [A] is a corona unit at the reverse side of the
transfer belt. It attracts toner to the transfer belt. The high voltage supply
board [B] applies a positive bias voltage to the transfer belt via the belt
transfer corona unit.
During the second and subsequent image transfer cycles, a positive voltage
higher than that used in the first cycle must be applied to the transfer belt to
attract the next color toner from the drum to the transfer belt. This is
because:
a) the attraction between the belt and the toner on the drum is reduced if
there is a layer of toner already on the belt,
b) there is residual voltage on the belt after the first color transfer. To
minimize toner scattering, the voltage is not raised after the second cycle
(also, further residual voltage effects and reductions in attraction
between belt and toner on the drum are not so significant after the
second cycle).
Belt transfer current [
µ
A]
Mode 1C 2C 3C 4C
Standard Speed
Mode
1C 70 – – –
4C 50 100 100 100
[A]
[B]
TRANSFER BELT UNIT
A166/A187/A189 2-102 SM
CÓPIA NÃO CONTROLADA
CÓPIA NÃO CONTROLADA