Sharp High voltage section, ADU unit SF-1120 only, Basic composition, Basic operation, DPHPS2

5Drive system division

The fuser unit is rotated by the main drive unit. In case of manual rotation of the fuser unit to remove paper jam, however, excessive loads may be applied to the gears. To prevent against this, the pressure of the upper/lower heat rollers is reduced when the machine clamshells are opened. In addition, the fusing gear is so constructed that the drive is not transferred to the drive system.

Proccess	Main motor
unit
Main drive unit
Stirring roller
DV drive unit	Fuser unit
MG roller
Cleaner	Transport
unit	unit
PS roller	Paper exit
Multi manual	roller
insertion paper
feed unit
(Option)
Transport
roller (upper)
Transport
roller (lower)

	Paper feed
Paper feed
	rive unit
unit

Paper feed unit

(7) High voltage section

1) General

There are three kinds of coronas; the main corona, the transfer corona, and the separation corona. The main corona employs the scorotron system, where the drum surface is evenly charged with negative charges controlled by the screen grid between the corona and the drum. The transfer corona is used to transfer toner images on the drum to the copy paper. A high, negative voltage is applied to the rear side of the paper. The separation corona applies AC corona to the copy paper to eliminate potential difference with the drum to allow separation of the paper.

The output voltage of the main charger and the transfer charger is supplied by transformer 1. The feedback current from the transfer charger is controlled to be constant and outputted to the main charger.

2) Basic composition

1Main (charging) corona – High voltage transformer (MHVG)

	Grid voltage	Developing bias voltage
Standard mode	–750V
Photo mode	–500V	–200V
TSM mode	–650V

2Main transfer corona – High voltage transformer (THVG)

–41μA (Electrode sheet front-rear balance difference: max. 7.0μA)

3Separation corona – High voltage transformer (SHVG) AC4KV ±0.1KV

Thermo control

	Thermistor
CPU	Heat roller
	Heater lamp

Heat roller surface temperature detection

The heat roller is heated by the heater lamp.

(When the heat roller surface temperature is 190 C˚ or lower, the heater lamp is actuated)

(8) ADU unit (SF-1120 only)

1) Basic operation

The ADU unit is stored above the paper cassette in the lower side of the copier. In the duplex copy mode, the copy paper is passed from the fusing unit through the reverse roller to the ADU, where it is aligned by the alignment plate. Then it is pressed onto the take-up roller by the paper holding plate, and only one sheet is transported by the paper feed and reverse roller. It is transported from through the transport roller to the copier, where duplex copy is made.

(Heater trouble)
Self diag display	Thermostat	Contact open (*)

Abnormal high temperature

•Abnormally high temperature (H3) 240°C or upper

•Abnormally low temperature (H4)

•Thermistor disconnection (H2)

* When the thermostat contact is open, it is required to press the reset button in the upper side of the thermostat. (The contact is not reset automatically.)

Reverse roller Cur correction unit

Paper feed roller Take-up roller

Transport upper unit

Rear edge plate	DPHPS2
	(Rear edge plate home
	position sensor)

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