3M 9800 User manual

3MVisualSystemsDivision
6801 RiverPlace Boulevard
Austin,Texas78726-9000 Printed inU.S.A. E3M7/96 78-6970-5568-5Rev.C
9800
OverheadProjector
Service Manual

3MOverheadProjector 9800 Series Table of Conents
i9800 Service Manual 3M 1996
1-1. Overview 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .
1-1-1.Parts Identification 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1-1-2.Physical Dimensions 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1-1-3.Safety Features 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1-2. Principles of Operation 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1-2-1.Optical Components 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1-2-2.Cooling 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1-2-3.Lamp Changer and High/Low Controls 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1-2-4.Color Tuning 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1-2-5.Calculating Projector-to-Screen Distance For Desired Image Size 1-6. . . . . . . . . . . . . . . . . .
2-1. Set-Up Procedure2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-2. Fold Down Procedure2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-3. Operating Instructions 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-4. Lamp Changer System 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-5. High/Low Lamp Setting 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-6. Lamp Replacement 2-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-1. Cleaning 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .
3-1-1.Projection Mirror 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-1-2.Projection Head Lens, Magnifier Lens Stage Glass 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-1-3.Fresnel Lens 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-1. Setting Up A Test Facility 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-1-1.Permanent Viewing Screen 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-1-2.Test Facility Layout 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-2. Optical Alignment 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-2-1.Lamp Position 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-2-2.Post Alignment 4-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-2-3.Head Alignment (Square Image) 4-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-2-4.Head Alignment – Centered Image 4-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-2-5.Color Tuning Adjustment 4-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-1. Open Projection Head Assembly 5-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-1-1.How to Replace the Mirror Assembly 5-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-1-2.How to Replace the Triplet Lens 5-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-2. Stage Assembly 5-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-2-1.How to Remove the Top Cover 5-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-2-2.How to Replace the Fresnel Lens 5-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-2-3.How to Replace the Top Cover Latch 5-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-2-4.How to Replace the Stage Glass 5-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-2-5.How to Replace the Power Switch Button 5-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-2-6.How to Replace the On/Off Switch Actuator 5-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-2-7.How to Replace the Power Switch Interlock 5-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-3. Optical/Lamp Assembly 5-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-3-1.How to Disassemble the Optical/Lamp Assembly 5-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-3-2.How to Replace the Hot Mirror 5-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-3-3.How to Replace the Condenser Lens 5-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-3-4.How to Replace the Lamp Socket 5-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3MOverheadProjector 9800 Series Table of Conents
ii9800 Service Manual 3M 1996
5-3-5.How to Replace the Reflector 5-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-4. Electrical Components 5-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-4-1.How to Replace the Overvoltage Protector Circuit Board (OPC) 5-11. . . . . . . . . . . . . . . . . . .
5-4-2.How to Replace the Transformer 5-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-4-3.How to Replace the Internal Voltage Switch 5-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-4-4.How to Replace the Interlock Switch 5-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-4-5.How to Replace the Thermostat 5-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-4-6.How to Replace the Circuit Breaker 5-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-4-7.How to Replace the Accessory Outlets 5-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-4-8.How to Replace the Power Cord 5-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-5. Fan Blade/Fan Motor 5-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-5-1.How to Replace Fan Blade and Motor 5-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-6. Post/Lock Assembly 5-17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-6-1.How to Disassemble the Post Assembly 5-17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-6-2.How to Disassemble the Post Lock Assembly 5-17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-7. Focus Assembly 5-18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5-7-1.How to Disassemble the Focus Assembly 5-18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-1. Troubleshooting Matrix 6-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-2. How To Check the Overvoltage Protector Circuit Board (OPC) 6-4. . . . . . . . . . . . . . . . . . . . . . .
6-3. Technical Assistance 6-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7-1. Electrical 7-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .
7-2. Wiring 7-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .

3MOverhead Projector 9800 Series Section 1 – Introduction
1-1
9800 Service Manual 3M 1996
1-1. Overview
This service manual contains projector specifications,
servicing instructions, operating instructions,
assembly and disassembly of parts instructions, a
troubleshooting guide and electrical and wiring
diagrams.
It is written for the service technician who has basic
electrical knowledge and technical skills. Refer to the
Illustrated Parts Breakdown (Publication
78-6970-5567-7) to cross-reference part numbers
required to order replacement parts.
7
2
1
34
5
6
8
9
10
12
11
13
17
24
16 15
22
18
20a
20c
14
19
21
20b
23
Figure 1-1. 9800 Projector
1-1-1. Parts Identification
1. Open Projection Head
2. Projection Mirror
3. Triplet Projection Lens
4. 1.3X Magnifier Lens
5. Arm
6. Focus Knob
7. Post
8. Post Latch
9. Post Cradle
10. Carrying Handle
11. Accessory Outlets (design varies by country)
12. Cord Wrap
13. Circuit Breaker (5 amps)
14. Power Cord
15. Stage Glass
16. Top Cover
17. Top Cover Release Latch (with interlock)
18. Color Tuning Adjustment (left side of machine)
19. Internal Voltage Switch (raise top cover to access)
20. Control Panel Door (with lamp interrupt switch)
a. Lamp Changer Dial
b. High/Low Lamp Brightness Switch
c. Lamp “Burned Out” or “Missing” Indicator
21. Pencil Holder
22. On/Off Power Switch
23. Machine Identification Plate
24. Internal Lamp Voltage Protector (raise top cover
to access)

3MOverhead Projector 9800 Series Section 1 – Introduction
1-2
9800 Service Manual 3M 1996
1-1-2. Physical Dimensions
The following dimensions and weights are
approximate.
Width: 429 mm 16.9 in.
Depth: 422 mm 16.6 in.
Height: 744 mm 29.3 in.
Weight: US
OUS 13.2 kg 29.0 lbs 14.7 kg 32.3 lbs
Stage Aperture: 286 mm x 286 mm
11.25 in. x 11.25 in.
1-1-3. Safety Features
All versions of the 9800 projectors include:
•Interlock – Shuts off power to projector when
the top cover is opened.
•Thermostat – Shuts off power to the lamp if
unsafe operating temperature should occur.
9800-77I
(13.9 in.)
(16.6 in.)
422mm
353mm
(23.2 in.)
589mm
(11.3 in.)
287mm
9800-78I
(16.9 in.)
429mm (17.0 in.)
432mm
(29.3 in.)
744mm
(9.9 in.)
251mm
Maximum
Figure 1-2. Physical Dimensions

3MOverhead Projector 9800 Series Section 1 – Introduction
1-3
9800 Service Manual 3M 1996
1-2. Principles of Operation
The 9800 projector is a transmissive projector. The
light source (lamp) is located in the base of the
projector where light is directed through an optical
path of reflectors, lenses and mirrors to produce the
projected image. Proper alignment of optical
components is essential for attaining maximum
resolution and brightness.
1-2-1. Optical Components
The following optical components (Figure 1-3) are
found in 9800 projectors:
•Lamp
•Reflector
•Condenser Lens
•Hot Mirror
•Fresnel Lens
•Stage Glass
•1.3X Magnifier Lens
•Projection Lens
•Projection Mirror
Lamps
Light illuminates from the lamp and is reflected along
the optical path. All 9800 projectors use lamp type
EVD 400W 36V.
Avoid excessive vibration or jarring of the projector
when the lamp is on. Because the lamp filament
becomes more brittle at the operating temperature,
shocks may cause premature failure of the lamp.
For maximum lamp life, the glass envelope should
not be touched by the fingers during replacement.
The oils on the skin may combine with the glass and
shorten the life of the lamp.
Reflector
The reflector is positioned under the lamp and collects
light from the lamp then directs it upward into the
condenser lens.
Condenser Lens
The condenser lens collects the light from the lamp
and directs it upward through the hot mirror.
Hot Mirror
The hot mirror filters the light to reduce the
temperature and directs it upward toward the Fresnel
Lens.
Fresnel Lens
The Fresnel lens bends the light from the hot mirror
and passes it through the stage glass into the 1.3X
magnifier and/or projector lens. Because the Fresnel
lens is made of plastic, it can be severely damaged if
the fan is stopped or the paths of cooling air are
blocked.
ReflectorLamp Condenser
Lens
Hot Mirror
Fresnel
Lens
Stage Glass
Projection
Mirror
Projection
Lens
Magnifier
Lens
9800-79I
Figure 1-3. 9800 Optical Properties
Stage Glass
The stage glass keeps the Fresnel lens clean and
protects the lens surface from scratches. It also
provides a convenient flat surface for placing
transparencies and other materials to be projected.
The stage glass is transparent to allow the light to pass
through and project the images placed on the glass
surface.

3MOverhead Projector 9800 Series Section 1 – Introduction
1-4
9800 Service Manual 3M 1996
1.3X Magnifier Lens
The 1.3X magnifier lens is used to enlarge the image
of LCD panels. When the magnifier lens is rotated
into position under the projection lens, light will pass
through the magnifier lens and then into the
projection lens. With the magnifier lens, the focal
length is reduced to 292 mm (11.5 in.).
Projection Lens
The projection lens collects the light and images
transmitted from the Fresnel lens and 1.3X magnifier
lens (if used) and projects them onto the surface of the
projection mirror. The projection lens is raised or
lowered by the focus mechanism to obtain the
sharpest projected image. The focal length of the
projection lens is 342 mm (13.5 in.).
The 9800 projector has an open head design with
triplet lens and 1.3X magnifier lens. Figure 1-4.
Open Head
Triplet Lens
FL=342 mm, 13.5 in.
9800–51I
1.3X Magnifier Lens
FL=292 mm, 11.5 in.
Figure 1-4. Projection Heads
Projection Mirror
The projection mirror redirects the light from the
projection lens to the projection screen. The angle of
the mirror determines the height of the projected
image on the projection screen.
The distance from the projection mirror to the
projection screen determines the size of the projected
image. Using the magnifier lens and/or LCD panels
will alter the projector to screen distances. Refer to
Section 1-2-5.
1-2-2. Cooling
Cooling of the overhead projector is accomplished by
a motor-driven fan located inside the projector body.
Cooling air is drawn into the projector through the
ventilation slots (A) and exits through opening B.
Figure 1-5.
It is important not to restrict the flow of cooling air by
placing the projector too close to the wall (leave
approximately one foot clearance) or placing objects
too close to the ventilation slots or under the projector
or by leaving foreign objects inside the projector.
B
A
9800–52I
A
Figure 1-5. Cooling

3MOverhead Projector 9800 Series Section 1 – Introduction
1-5
9800 Service Manual 3M 1996
1-2-3. Lamp Changer and High/Low Controls
Lamp Changer
The 9800 projector has a lamp changer feature. The
lamp changer dial is accessed by lifting the control
panel door. Rotate the lamp changer dial left or right
to select the alternate lamp.
Note
The control panel door must be closed to
illuminate the lamp.
High/Low Lamp Brightness
The High/Low lamp brightness switch* is located
under the control panel door. “High” is recommended
for LCD projection panels and “Low” is
recommended for normal use.
* Early machines used a knob. Starting with serial
number 615042, a switch replaced the knob.
Note
Use the “Low” setting to extend lamp life.
1-2-4. Color Tuning
Color tuning adjusts the distance between the lamp
and the Fresnel lens to remove yellow/orange to
brown or blue colors from the corners of projected
images. See Section 4-2-5 for instructions.

3MOverhead Projector 9800 Series Section 1 – Introduction
1-6
9800 Service Manual 3M 1996
1-2-5. Calculating Projector-to-Screen
Distance For Desired Image Size
The size of the projected image is determined by the
following factors:
•Projector-to-Screen Distance
•Focal Length of Projection Head
•Stage/LCD Panel Aperture Size
•Screen Size (Image Size)
For a given screen size, use the following formula or
refer to Figure 1-6 to calculate the projector to screen
distance needed to fill the screen.
D = F ( S + 1)
A
D = PROJECTOR-TO-SCREEN DISTANCE
F = FOCAL LENGTH OF HEAD
S = SCREEN SIZE
A = STAGE/LCD PANEL APERTURE SIZE
For example: To fill a 152 cm x152 cm (60 in. x 60
in.) screen, how far from the screen should you
position a 285 mm (11.2 in.) stage projector with an
342 mm (13.5 in.) focal length.
D = 34.2 cm ( 152 cm + 1)
28.5 cm
D = 217 cm (86 in.)
To use Figure 1-6, locate the specific screen size on
the right and read the corresponding projector distance
at the bottom. For LCD panels, locate the LCD panel
size in the chart and read the corresponding projector
to screen throw distance to the right.
Note
Focusing an overhead projector at extreme
distances (near or far) may result in poor
overall image quality and require a Color
Tuning adjustment. See 1-2-4.

3MOverhead Projector 9800 Series Section 1 – Introduction
1-7
9800 Service Manual 3M 1996
127 cm
x
127 cm
152 cm
x
152 cm
177 cm
x
177 cm
213 cm
x
213 cm
243 cm
x
243 cm
50 in. x 50 in. 60 in. x 60 in. 70 in. x 70 in. 84 in. x 84 in. 96 in. x 96 in.
9800 EVD
FL = 342 mm
(13.5 in.)
187 cm
(74 in.) 217 cm (86 in.) 248 cm (98 in.) 291 cm (114 in.) 327 cm (129 in.)
9800 EVD
FL = 342 mm x50 in. x60 in. x70 in. x84 in. x96 in.
FL
=
342
mm
(13.5 in.) x = 21.3 cm
(8.4 in.) 239 cm
(94 in.) 279 cm (110 in.) 320 cm (126 in.) 377 cm (148 in.) 426 cm (168 in.)
x = 24.1 cm
(9.5 in.) 215 cm
(85 in.) 251 cm (99 in.) 287 cm (113 in.) 338 cm (133 in.) 381 cm (150 in.)
x = 26.4 cm
(10.4 in.) 199 cm
(78 in.) 232 cm (91 in.) 265 cm (104 in.) 311 cm (122 in.) 351 cm (138 in.)
9800 EVD
FL = 292 mm
(
11.5 in.
)
x = 21.3 cm
(8.4 in.) 203 cm
(80 in.) 238 cm (94 in.) 273 cm (107 in.) 321 cm (126 in.) 363 cm (143 in.)
(11
.
5
in
.
)
x = 24.1 cm
(9.5 in.) 183 cm
(72 in.) 214 cm (84 in.) 244 cm (96 in.) 288 cm (113 in.) 324 cm (128 in.)
x = 26.4 cm
(10.4 in.) 170 cm
(67 in.) 198 cm (78 in.) 226 cm (89 in.) 266 cm (104 in.) 299 cm (118 in.)
Figure 1-6. Projector-To-Screen Distances

3MOverhead Projector 9800 Series Section 1 – Introduction
1-8
9800 Service Manual 3M 1996
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3MOverhead Projector 9800 Series Section 2 – Operating The 9800 Projector
2-1
9800 Service Manual 3M 1996
2-1. Set-Up Procedure
1. Release post cradle latch and lift the post (1) until
it locks into place.
Figure 2-1. Lift Post
2. Plug power cord (2) into an electric outlet.
3. Push power switch to the “On” position.
4. Adjust mirror (3) to position image on screen and
rotate focus knob (4) for clearest image.
3
4
9800-81I
Figure 2-2. Adjust Mirror and Focus
5. Rotate color tuning knob for color-free image.
See Color Tuning for details.

3MOverhead Projector 9800 Series Section 2 – Operating The 9800 Projector
2-2
9800 Service Manual 3M 1996
2-2. Fold Down Procedure
1. Unplug power cord (1) and coil onto cord wrap
(2).
2. Rotate 1.3X magnifier lens (3) under projection
lens.
1
2
3
9800-82I
Figure 2-3. Position 1.3X Magnifier Lens
3. Rotate focus knob (4) clockwise to raise
projection head to maximum position.
Figure 2-4.
4. Release post latch (5) and lower post until it rests
and locks in the post cradle.
Figure 2-4. Raise Head, Lift Post Latch and Fold Post
5. Rotate focus knob (6) counterclockwise to lower
head until it stops.
Figure 2-5. Lower Head To Projector Body
6. To move projector, lift from bottom or use the
carrying handle.
Figure 2-6. Lift Projector From Bottom

3MOverhead Projector 9800 Series Section 2 – Operating The 9800 Projector
2-3
9800 Service Manual 3M 1996
2-3. Operating Instructions
1. Position projector in front of projection screen.
The distance from the screen controls the size of
the projected image.
2. Plug power cord into an electric outlet.
3. Push power switch to “On” to illuminate lamp.
4. Rotate projector (1) until projected light beam is
perpendicular (90) to the screen surface. The
height at the left and right sides of the projected
image should be equal. Figure 2-7.
9700–33A
Figure 2-7. Position Projector To Screen
5. Adjust angle of projection mirror (2) to raise or
lower the image on the screen. Figure 2-8.
6. For best results, tilt projection screen (3) toward
projector until the top and bottom of the projected
image appear square and without distortion.
Figure 2-8.
7. Place film transparency or LCD projection panel
on the stage glass (4).
8. Set lamp brightness to “High” or “Low” position.
See High/Low Lamp Setting.
9. Rotate focus knob (5) for sharpest image.
10. Rotate magnifier lens (6) under projection lens to
enlarge LCD projection panel or transparency film
image size by 1.3X. Adjust focus knob (5) for
sharpest image.
Note
The magnifier lens glass and metal frame get
warm to the touch during normal use. Grasp
the insulated tab to rotate the lens.
Figure 2-8. Operating The 9800

3MOverhead Projector 9800 Series Section 2 – Operating The 9800 Projector
2-4
9800 Service Manual 3M 1996
2-4. Lamp Changer System
When a lamp burns out, a red X (Figure 2-9) will
appear on the closed control panel door.
9800-83I
Figure 2-9. Control Panel Door Closed
1. Open control panel door (1). Figure 2-10. Power
to lamp is disconnected by lamp interrupt switch
(2) in door.
Note
The red LED lamp (5) will light if the selected
lamp (position 1 or 2) is burned–out or
missing.
5
Figure 2-10. Control Panel Door Open
2. Rotate the Lamp Changer Dial (3) to position 1 or
2.
3. Close control panel door to restore power and
illuminate lamp.
Note
The red X will light when a lamp is either
defective or missing.
Important
Lamp will not illuminate unless control
panel door is closed.
2-5. High/Low Lamp Setting
Activate the High/Low switch to select High (bright)
or Low (normal) lamp illumination.
1. Open control panel door (1). Power to lamp is
disconnected by interlock (2) in door.
Figure 2-10.
2. Depress High/Low switch (4) to set desired
brightness.
a. = High: Brightest image, shorter lamp life
b. = Low: Normal image, longer lamp life
Note
Operating the projector in the “low” setting
will extend lamp life.
3. Close control panel door to test lamp brightness.

3MOverhead Projector 9800 Series Section 2 – Operating The 9800 Projector
2-5
9800 Service Manual 3M 1996
2-6. Lamp Replacement
EVD – 36V, 400W 9800–53I
Figure 2-11. EVD Lamp Type
To replace a lamp:
1. Push power switch to “Off” and unplug projector.
2. Press release latch and lift to open the top cover.
Figure 2-12.
Figure 2-12. Top Cover Latch
3. Allow lamp to cool before replacing.
!
Lamp and adjacent metal parts are hot. Allow
lamp to cool before replacing.
4. Release spring catch (1) and open condenser lens
frame. Figure 2-13.
5. Remove old lamp (2) and discard. Figure 2-13.
6. Insert new lamp. Push lamp fully and squarely
into socket. Figure 2-13.
Note
Do not touch bulb glass with fingers.
Figure 2-13. Removing Lamps
7. Close condenser lens frame and secure with
spring catch.
8. Close stage cover and plug power cord into outlet.
Important
Lamp will not illuminate unless Top Cover
is closed and latched.

3MOverhead Projector 9800 Series Section 2 – Operating The 9800 Projector
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9800 Service Manual 3M 1996
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3MOverhead Projector 9800 Series Section 3 – Maintenance
3-1
9800 Service Manual 3M 1996
3-1. Cleaning
For best performance, the optical surfaces of a
projector must be free of excess dust and surface dirt.
Procedures for cleaning the following optical surfaces
are covered in this section:
•Projection Mirror
•Projection Head Lens
•Magnifier Lens
•Stage Glass
•Fresnel Lens
Note
Use 3MOverhead Cleaner 676 (Figure 3-1)
to remove surface dirt from the stage glass
and projector lens.
Figure 3-1. 3MOverhead Cleaner 676
3-1-1. Projection Mirror
1. To remove surface dirt, use a soft brush or
compressed air. Figure 3-2.
2. To remove smudges or fingerprints, dampen a
cotton ball or soft, lint-free cloth with 3M
overhead cleaner and gently rub mirror surface.
Figure 3-3.
Caution
!
The projection mirror is a front surface mirror.
Hard rubbing will damage the mirror surface.
9800–54I
Figure 3-2. Removing Surface Dirt
9800–55I
Figure 3-3. Removing Smudges or Fingerprints

3MOverhead Projector 9800 Series Section 3 – Maintenance
3-2
9800 Service Manual 3M 1996
3-1-2. Projection Head Lens, Magnifier Lens
Stage Glass
1. Use 3MOverhead Cleaner and a soft, lint-free
cloth to clean the surfaces of the head lenses,
magnifier lens and stage glass. Figure 3-4.
Caution
!
Never use paper lens tissues on projection lenses
because they may damage the lens surface.
2. Dampen a soft, lint-free cloth with 3M overhead
cleaner and gently rub surface.
3. Remove excess cleaner and dry surface with a
clean, soft, lint-free cloth.
9800–56I
Figure 3-4. Cleaning Lens, Stage Glass, Body Mirror
3-1-3. Fresnel Lens
In the 9800 projector, the Fresnel Lens is a doublet
lens with a smooth surface on both sides.
Caution
!
Do not clean the Fresnel Lens by immersing or
flushing in water.
1. Remove the Fresnel Lens (see Section 5-2-2 for
instructions).
2. Dampen a lint–free cloth with a liberal amount of
3M overhead cleaner or equivalent (25%
Isopropyl alcohol and water).
3. Apply light pressure and wipe the Fresnel lens in
a circular motion.
4. Wipe dry with a clean cloth or blow dry with
compressed air.

3MOverhead Projector 9800 Series Section 4 – Adjustments
4-1
9800 Service Manual 3M 1996
4-1. Setting Up A Test Facility
Reliable check-out and optical alignment of overhead
projectors can be accomplished only if proper testing
facilities are available. The following items,
described in this section, are required to provide
proper testing:
•Permanent viewing screen
•Permanent test facility (stand or bench)
•Required tools
4-1-1. Permanent Viewing Screen
A permanent viewing screen with a flat non-reflective
white surface can be provided by applying a flat white
paint to a 152 cm by 152 cm (60 in. x 60 in.) area of a
smooth wall. If a smooth wall is not available, a
piece of wallboard painted white, or a white window
shade of the proper size, can be mounted in the test
area. A portable screen may also be used.
A test stand or bench should be permanently located
about eight feet from the screen. It should be high
enough to provide easy access to all parts of the
overhead projector when it is placed on the stand for
testing. An electrical outlet and a switch should be
built into the test stand to facilitate making electrical
connections to the projector.
4-1-2. Test Facility Layout
To eliminate vertical and horizontal keystoning, it is
very important to align the projector to be perfectly
square with the viewing screen. Keystoning will
result in unequal focusing of projected images at the
four corners, and will especially affect resolution.
Use the steps below to set up a test facility that will
provide the proper screen to projector relationships.
1. Select a smooth wall with a 152 cm x 152 cm (60
in. x 60 in.) area and place a sturdy bench or test
stand about eight feet away from the wall
(Figure 4-1).
2. Set the overhead projector on the test stand so that
it points towards the wall.
Figure 4-1. Test Facility Layout
3. Measure the vertical distance from the floor to the
center of the front projection lens (Figure 4-2).
a. Follow a floor or ceiling tile from the
projector to the wall or stretch a string from
the center of the projection lens to the wall
and use a carpenter’s square to find the point
at which the string is perpendicular to the
wall.
b. Mark a spot on the wall that is the same
distance (height) from the floor as the center
of the projection lens.
9800-85I
Figure 4-2. Projector to Screen Alignment
4. Mark the position of the stand legs on the floor
and the position of the projector base on the stand.