JVC 340 SC - Manual (Page 22)

Chapter 2—Functional Descriptions
2-10 Model 330, 340SC, and 370SC Service Manual
When the Arc Lamp supply first turns on, it supplies 170V to the ignitor. The
ignitor then senses this voltage, activates it’s on-board supply, and produces a
1
µ
S, 38KV pulse to the Arc Lamp. This pulse strikes an arc in the lamp. The Arc
Lamp supply then provides the high current necessary to sustain the arc in the
lamp. Refer to Figure 2-5 and the summary below for a description on the Arc
Lamp and Ignitor timing.
LAMP-ON COMMAND
IGNITOR FIRES
38 KV
170V
22-30V*
0V
/LAMPLIT
/ALENBL
/FANENBL
LAMP-OFF
COMMAND FAN DISABLE
CPU TIME-OUT
5-10 MINUTES
ARC LAMP ON
1 2
3
4 5
6
*22-30V depending on projector model.
Figure 2-5 Arc Lamp Ignitor Timing Diagram
Arc Lamp/Ignitor Timing Diagram Summary:
1. The operator powers Arc Lamp on. /ALENBL and /FANENBL from
System Controller Board are pulled low. SPS receives /ALENBL from
SCB and turns on the Arc Lamp PS.
2. Ignitor receives +170V boost voltage from the Arc Lamp PS.
3. Ignitor steps up the +170V boost voltage to a 1
µ
sec pulse, approximately
38KV.
4. Arc Lamp ignites from the 38kV pulse.
5. High current (about 68-100A depending on projector model) begins
through Arc Lamp and voltage drops to +22-30V (depending on projector
model).
6. /LAMPLIT signal goes to SCB to inform board that Arc Lamp is lit.