Epson DFX-8500 service manual ‰General, ‰37V line block ½, ‰37V line block 2/2, ‰Cooling fan

OPERATING PRINCIPLES

‰￿General :

The power supply board converts the AC input voltage to the DC voltages required to operate the printer. The AC voltage is input to the AC inlet, and is supplied to the C204 PSB/PSE board via the power switch and a fuse.

Two main switching regulator circuits consist of two blocks, +37 V Lines ½ and 2/2. The one convert the AC voltage to the +37 VDC specially for the print head coils drive requirement. The other convert the AC voltage to the +37 VDC for the printer mechanism drive power requirement (motors, solenoid, etc.) and for the source of +5 V DC regulator circuit requirement (Refer to Table 2-3.).

‰￿37V line block ½ :

The generated +37 VDC is divided into two destinations; nine of the eighteen printhead pins (pins 1, 2, 7, 9, 10, 11, 12, 15, and 17); the other to nine of the eighteen printhead pins (pins 3, 4, 5, 6, 8, 13, 14, 16 and 18).

‰￿37V line block 2/2 :

The generated +37 VDC is supplied to the motors and plunger on the printer mechanism, it also supplied to the +5VDC regulator circuit and it output. +5V DC is supplied to the logic circuit on the main circuit.

‰￿Cooling fan :

The C204 PSB/PSE board includes a cooling fan that is driven by the +37 VDC. The fan lowers the temperature of the PSB/PSE board circuit components, and it also lowers the CR motor temperature because the motor locates on the way of an air exhaust channel of the fan.

Table 2-3. PSB/PSE Board Output DC Voltages

Voltage	Board	Application
+37V (VP1-GP1)	C204 DRV-B	∙	Printhead drive ½
+37 V (VP2-GP2)	C204 MAIN	∙	Printhead drive 2/2
+37 V (VP3-GP3)	C204 DRV	∙	CR motor drive
		∙	PF motor drive
		∙	PG motor drive
		∙	RF motor drive
		∙	HF drive
		∙	CR fan drive
		∙	Plunger drive
		∙	Optional Cutter’s motor drive
	C204 PSB/PSE	∙	Cooling fan on the PSB/PSE unit
+5 V -GL	C204 MAIN	∙	All logic systems operating voltage
	C204 DRV	∙	PF motor hold voltage
	C204 DRV-B	∙	Plunger hold voltage
	C204 PNL	∙	PG motor hold voltage
		∙ Power for all the sensors
VX-GL	C204 MAIN	∙	Voltage for power system pull-up. It is switched
	C204 DRV		by VXCNT signal of the CPU (IC2).
	C204 DRV-B

Rev. B 2-15