Hughes JVC Projector 250 Service Manual

							Chapter 3---Electrical
Model 250 Service Manual 3-15
3.4 Igniter Assembly
The Igniter Assembly consists of the Igniter and the Laser Power Supply. The
Igniter and Laser Power Supply are replaced as one unit.
Igniter Assemby - Main Functions:
!
 Generates 32 kV pulse to light Arc Lamp Power
!
 Acts as link between Arc Lamp Power Supply and Arc Lamp during normal
Arc Lamp operation
Igniter Assembly - Inputs
!
 +170 V - From the Arc Lamp Power Supply during Arc Lamp lighting.
!
 25-31 V at 70-85 A - From Arc Lamp Power Supply during normal Arc Lamp
operation.
Igniter Assembly - Outputs
!
 32 kV - to the Arc Lamp during Arc Lamp lighting.
!
 25-31 V at 70-85 A - From Arc Lamp Power Supply during normal Arc Lamp
operation.
Igniter Assembly -  Operation
The Igniter has two functions: to light the Arc Lamp and to act as a link between
the Arc Lamp Power Supply and the Arc Lamp during normal Arc Lamp
operation. The Igniter contains the spark gap and the step-up transformer that
supplies the 32 kV pulse that lights the Arc Lamp. During lighting of the Arc
Lamp, the Arc Lamp Power Supply receives the /LAMP_ENA signal from the
System Controller PCB, it sends a +170 VDC boost voltage to the primary coil of
the Igniter. The Laser Power Supply charges up a capacitor. When the capacitor
reaches  +5.5 kV, the spark gap arcs causing a very high voltage pulse
(approximately 32 kV) to be induced onto the Igniter Transformer step-up
(secondary) coil. The high voltage pulse goes to the Anode of the Arc Lamp. The
spark generated by the 32 kV pulse creates an arc inside the Xenon bulb that
ignites the Arc Lamp. 
						

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Model 250 Service Manual
Figure 3-7  
Igniter Assembly.
Igniter Assembly -  Service Adjustments
There are no service adjustments performed on the Igniter Assembly.
Igniter Assembly - Remove and Replace
Replace the Igniter and the Laser Power Supply as one unit.
Tools Needed
2 - 7/16-inch wrench (one open end wrench)
#1 Pozi-drive Phillips-head screwdriver
Parts Needed
Igniter Assembly  p/n 106570
To remove the Igniter Assembly
1. Power the projector Off by IR Remote or PC, and allow the cooling fans
to run until they shut off.
2. Turn the AC Circuit Breaker to the OFF position and unplug the AC
Power Cord.
3. Remove the front cover (see Projector Covers section 6.1).
4. Disconnect the white Anode cable from the output of the Igniter
Transformer using the 7/16-inch wrench. Use one wrench to hold the
inside nut and the other wrench to loosen the outside nut. 
						

							Chapter 3---Electrical
Model 250 Service Manual 3-17
5. Disconnect the orange cable attached to the input side of the Igniter
Transformer using the 7/16-inch wrench. This cable will have black shrink
sleeving on it. It goes to the negative terminal of the Arc Lamp Power
Supply.
6. Disconnect the orange Cathode cable from the Igniter ground post using
the 7/16-inch wrench. Remove the other orange cable that goes to the
positive terminal of the Arc Lamp Power Supply.
7. Remove the five #1 Pozi-drive Phillips-head screws.
8. Lift the Igniter Assembly out of projector.
9. Reverse the procedure to install the Igniter Assembly. 
						

							Chapter 4---Optical
Model 250 Service Manual 4-1
4.0 Optical
Contents
4.1  Arc Lamp...................................................................................................... 4-2
4.2  Optical Path .................................................................................................. 4-7
4.3  ILA
®............................................................................................................. 4-13
4.4  Relay Lenses ................................................................................................ 4-20
4.5  Projection Lens............................................................................................. 4-20
  CAUTION!  Before performing procedures in this chapter,
review the chapter on Safety at the beginning of this manual.
  WARNING!!!  When performing procedures in this chapter
that require projector covers to be off, wear high voltage gloves
(ANSI/ASTM 10,000 volt rated) when working near the CRTs, Arc Lamp,
or power supplies. Wear safety goggles (rated X5) when working
anywhere near the light path from the arc lamp or the projection lens.
Dangerous levels of ultraviolet and infrared radiation, dangerous glare, very high
temperatures (180°C to 300°C) and high internal gas pressure are present at the
Xenon Arc Lamp. The lamp is contained in a protective reflector-housing module
and should not be operated outside this housing or outside of the projector.
When replacing the Arc Lamp, replace it as an entire module, as shown in this
manual. Do not open the lamp housing or attempt to replace the Arc Lamp
inside its module! Do not touch the Arc Lamp, or any connections, when the
lamp is ignited or is arcing.
Any servicing of the Arc Lamp must remain restricted to Hughes-JVC Certified
Technicians. 
						

							Chapter 4---Optical
4-2 
Model 250 Service Manual
4.1 Arc Lamp
The Arc Lamp is the beginning of the high intensity Light Path. It is located
inside a housing on the right side of the Optical Support Assembly (see Figure
4-5).
Arc Lamp - Main Functions:
The Arc Lamp is a single component composed of a Xenon gas bulb at the center
of a compound elliptical reflector. It supplies the high intensity white light used
by the projector to put a very bright image on the screen. The expected 50% life
(half of initial light output) of an Arc Lamp is approximately 1000 hours.
Arc Lamp - Inputs
!
 32 kV pulse to light the Arc Lamp Power Supply
!
 2 kW constant power during normal operation
Arc Lamp - Operation
The Arc Lamp Power Supply and the Igniter Assembly work together to produce
a 32 kV pulse that ignites the Arc Lamp.  After the Arc Lamp lights, the voltage
from the Arc Lamp Power Supply drops to a constant 25-31 volts at 70-85 amps.
It will stay at this level during normal Arc Lamp operation.
Arc Lamp - Service Adjustments
When a new Arc Lamp is installed, it will need to be aligned using the Arc Lamp
adjustment fixture located inside the Arc Lamp housing (see Figure 4-2).
Arc Lamp Adjustment
Tools Needed
Large Flatblade screwdriver
4-mm Hex-head wrench
Equipment Needed
Minolta Illumination Meter T-1 or equivalent
To align the Arc Lamp:
1. Remove the front cover (see Section 6.1).
2. Loosen the spider lock down bolt (see Figure 4-4).
3. Power the projector ON and let it run for 15 minutes to stabilize.
4. Verify that the Shutters on Hide box is checked in the System-
Preferences menu, then use the RGB key and the HIDE key to hide Red
and Blue. This prevents light coming from the Red and Blue ILA
®s.
5. Open the fan door of the Arc Lamp Enclosure housing using the large
Flatblade screwdriver to rotate the retaining screws 90°  This gains access
to the three Arc Lamp alignment screws. The Arc Lamp fan disconnects
when this door is opened. 
						

							Chapter 4---Optical
Model 250 Service Manual 4-3
  CAUTION! Fan disconnection is acceptable for a short
period of time only (preferably 
						

							Chapter 4---Optical
4-4 
Model 250 Service Manual
Hot spot
off-center
Figure 4-1   
Arc Lamp “Hot Spot” (brightest area) is off-center vertically and
horizontally. Adjust to center the “hot spot”.
 
Figure 4-2  
Arc Lamp alignment fixture.
  
						

							Chapter 4---Optical
Model 250 Service Manual 4-5
Figure 4-3  
Arc Lamp Assembly access door.
Arc Lamp - Remove and Replace
The Arc Lamp Enclosure Assembly consists of the Xenon Arc Lamp module and
blower. Replace the blower together with the Arc Lamp Module.
Tools Needed
7/16 inch wrench
#1 Pozi-drive Phillips-head screwdriver
Diagonal wire cutters (or equivalent)
Parts Needed
Arc Lamp p/n 106298
  WARNING!!!  Dangerously bright light and high current
exist in this area of the projector. Before proceeding with the removal of
any subassemblies below, verify that the circuit breaker at the rear of the
projector is turned off and the power plug is removed from the AC outlet.
To Remove the Arc Lamp:
1. Power off the projector by IR Remote or PC, and allow the cooling fans to
run until they shut off.
2. Turn the AC Circuit Breaker to the OFF position but leave the AC Power
Cord plugged in to maintain chassis ground.
3. Remove the front cover (see Section 6.1).
4. Disconnect the white Anode cable from the Igniter, using the 7/16-inch
wrench (see Figure 3-7). 
						

							Chapter 4---Optical
4-6 
Model 250 Service Manual
5. Disconnect the orange Cathode cable from the Igniter, using the 7/16-inch
wrench (see Figure 3-7).
6. Cut the cable tie that is wrapped around the ferrite inductor (metal tube
with white cap below the blower).
7. Disconnect the Arc Lamp door fan cable. This cable runs through the door
and out the bottom of the Arc Lamp Assembly housing (below the right
side inFigure 4-3). It provides power to the Arc Lamp door fan through the
white socket shown to the right of the Arc Lamp fan in Figure 4-3.
Disconnect the cable at the socket connection below the Arc Lamp
housing. Disconnect the top fan cable.
8. Disconnect large blower fan connector.
9. Remove the FA shield from the top of the Arc Lamp. Three #1 Pozi-drive
Phillips-head screws hold the FA shield in place (see Figure 4-4).
10. Remove the two retaining bolts for the Arc Lamp, using a 10-mm socket
and driver.
11. Reverse the procedure to install the Arc Lamp. Check and adjust the Arc
Lamp alignment after replacing. There is no Arc Lamp current adjustment. 
						

							Chapter 4---Optical
Model 250 Service Manual 4-7
Figure 4-4  
Arc Lamp Assembly top view.
4.2 Optical Path
Optical Path - Main Function
!
 Transports the Arc Lamp high intensity light from the Arc Lamp to the
ILA® and from the ILA® to the Projection Lens
!
 Removes the Infrared light that contains most of the heat
!
 Removes the unwanted Ultraviolet light
!
 Condenses the white light using the Light Pipe for a uniform output
!
 Separates the white light into its RGB component colors using Dichroic
Beamsplitters.
!
 Polarizes each of the component RGB light beams
!
 Combines the component RGB image beams into one beam and delivers
that to the Projection Lens.