JVC 370 SC, 340 SC service manual ∇ Model 330. Model 340SC = +25V/80a Model 370SC = +30V/100a

Chapter 2—Functional Descriptions

The Arc Lamp power supply is a current-controlled supply with an open circuit voltage of about 170V. When the Arc Lamp is operating at steady state, the power supply provides the current set by the technician. The output of the supply has a large capacitor that will, on initial ignition of the Arc Lamp, provide the very high initial current necessary to ionize the xenon gas in the lamp and sustain the arc. The current setpoint is initially set at the factory and must be reset by the technician whenever an Arc Lamp is replaced.

AC INPUT		POWER		STANDBY/
		FACTOR
220-240vac
		CORRECTION		I/O CONTROL
					J502
50Hz
				+5v, +24v
			/FANENBL			To
From						Backplane
System				LOW VOLTAGE	J500
Controller				Power Supply
	J502		/LVPSNBL	+5v,+6.3v,+-15v,
				+24v,+48v,+107v
				ARC LAMP		To
				Power Supply	J503 (-)	Arc Lamp
				and Boost
					J504 (+)	Via
			/ALENBL	+22v/68a ∇
						Ignitor
				+170v/1.0a

∇Model 330. Model 340SC = +25V/80a; Model 370SC = +30V/100a.

Figure 2-3System Power Supply Block Diagram.

Normal system power-up (Electronics and Lamp):

1.Upon receipt of Power-On command, SCB pulls /FANENBL and /ALENBL lines low.

2.+24V Standby and Arc Lamp power supplies turn on.

3.When Arc Lamp lights (run voltage sensed by a window comparator in the SPS), SPS pulls /LAMPLIT line low.

4.When SCB senses /LAMPLIT low, SCB pulls /LVPSNBL line low.

5.Low voltage supplies turn on.

6.SCB senses +5V supply at correct level and enters normal program sequence.

Lamp only power-up:

1.Upon receipt of Lamp-On command, SCB pulls /FANENBL and /ALENBL lines low.

Model 330, 340SC and 370SC Service Manual 2–7