Olympus BHTU User manual

MODELBHTU
BIOLOGICAL MICROSCOPE
scanned on Nov. 6, 2009 by J.G.McHone
for personal use only, not for sale
,.---- WARNING ------,
This instruction manual is for use of your instrument.
Before
putting it into operation, we recommend you
read this manual carefully in order to familiarize your-
self fUlly with its use so that you may obtain opti-
mum performance.
OLYMPUS'"
1111111111111111111111111~ 11111111111111111111I1111111
AX5?51 .

This instruction manual has been written for the use of the Olympus Biological Microscope
Model
BHTU. It is recommended that you read the manual carefully in order to familiarize
yourself
fully with the use of the microscope, so that you will obtain optimum performance.
IMPORTANT
Observe the following points:
•Operation
1. Always handle the microscope with the care it deserves, and avoid abrupt motions.
2. Avoid the use and maintenance of the microscope in direct sunlight, high temperature and
humidity, dust and vibration.
3. Only use the tension adjustment ring for altering the tension of the coarse adjustment
knobs. (Do
not twist the two coarse adjustment knobs in opposite directions simultaneous-
Iy, as this will cause damage.)
4. Make sure that the voltage selector switch on the bottom base of the microscope stand
is set to conform with the local mains voltage.
5. Ground the microscope in case there is no ground terminal in your mains line .
•Maintenance
,. Lenses must always be kept clean. Carefully wipe off oil or fingerprints deposited on the
lens surfaces
with gauze moistened with asmall amount of xylene, alcohol or ether.
2. Do not use organic solutions to wipe the surfaces of various components. Plastic parts,
especially, should
be cleaned with neutral detergent.
3. Never disassemble the microscope for repair. Only authorized Olympus service personnel
should make repairs.
4. The microscope should be covered with the vinyl dust cover provided and stored in aplace
free from humidity and fungi.

I.
II.
III.
STANDARD CONFIGURATIONS
NOMENCLATURE
ASSEMBLy............ .....
CONTENTS
2
3
4
IV. IDENTIFICATION AND FUNCTION OF VARIOUS COMPONENTS
V.
VI.
VII.
OPERATION
A. Switching ON the Light Source
IVoltage Adjustment and Light Intensity I
I
LP (Light Intensity Presetting) Switch I
B. Placement of aSpecimen Slide .
IWhite Cover for Condenser
ICover Glass I
ISpecimen Slide I
IStage I
C. Observation Tube
1. Interpupillary Distance Adjustment
2. Diopter Adjustment
3. Light Path Selector
D. Condenser Adjustment
1. Condenser Centration
IFiled Iris Diaphragm I
IAperture Iris Diaphragm
E. Focusing Adjustment .
1. Tension of Coarse Adjustment Knobs and Fine Adjustment
IUse of Rubber Cap for Fine Adjustment Knob
2. Pre-Focusing Lever
F. Use of Immersion Objectives
G. Photomicrography .
OPTICAL DATA
TROUBLESHOOTING GUIDE
6
9
9
10
13
14
15
15
17
18

I. STANDARD CONFIGURATIONS
"",
Model
Component BHTU·ll1
BHTU-112 BHTU·312
Microscope stand BHTU·F 111
with quintuple revolving nosepiece
8inocular tube BH2·B130 1 1 0
Observation tubes Trinocular tube BH2·TR30 0 0 1
Square mechanical stage with right-hand low BH2.SVR2 1 1 1
drive coaxial controls and specimen holder
Swing-out condenser BH2·SC 111
Halogen lamp holder LS·20H 111
Halogen bulbs
6V20WHAL 22 2
DAch.
4X, DAch. lOX, DAch, 40X,
10 0
DAch. lOOX (oil) each
Objectives D
Plan 4X, 0Plan lOX, D Plan 40X 01 1
D Plan lOOX (oil) each each
Eyepieces, paired
WKlOX 111
Photo eyepiece NFK3.3X 001
Filter
KB·4 111
Immersion oil, bottled 111
Vinyl dust cover 111
2

II. NOMENCLATURE
The Model BHTU consists of various components and interchangeable accessories as shown in
the
photo below. Awide variety of combinations, standard or optional, is available according
to your requirements.
Eyepiece
Objective
Stage
Condenser
-
3
Observation tube
Micoscope stand
For biological use
Halogen lamp
holder
--
--
LP (Light IntensityPresetting) switch

III. ASSEMBLY
This picture illustrates the sequential procedure of assembly. The numbers Indicate the
order of assembly of various components. Remove dust caps before mounting components.
Take care to keep all glass surfaces clean, and avoid :;cratching the glass surface.
NOTE: For numbers ~ and f) please refer to explanations in detail on the next page.
e®
Condenser
(The N.A. scale
engraved on the con-
denser shou ld face the
microscope front.)
-.. To AC
®outlet
Halogen bulb
Q
CD,
~ Halogen lamp
9J holder
Condenser clamping screw
Observation tube
Observation tube clamping screw
Circular dovetail mount
Eyepjece
0)
.~
®
.g Objective
Specimen
holder
Clamping
screws
~tage L' _I .......;~;..-
Stage mounting dovetail
LP (Light Intensity Presetting) switch
4

• Explanations in detaiI
9 Mounti ng the stage
11 Loosen the stage clamping screw CD by
rotating counterclockwise. (Fig. 1)
2) Insert the stage into the mounting dove-
tail of the microscope stand slowly and
lock
with clamping screw.
fJ Mounting the observation tube
1) Loosen the clamping knob CD fully.
(Fig.21 Pull spring-loaded clamping knob
CD. This will cause the locating pin <V to·
withdraw. If the pin does not, loosen the
screw further until the pin withdraws.
2) With clamping knob CD pulled out. insert
the circular dovetail of the observation
tube into the ring dovetai I.
3) Tighten the clamping knob.
5
Fig.
Fig. 2

Photo tube
Condenser height
adjustment knob
Pre- focusi ng lever
Line
cord
-
7
Diopter adjustment
ring
X-axis low drive
control knob
Xexcursion range:
76 mm.
Y-axis low drive
control knob
Yexcursion range:
50mm.
Field iris diaphragm ring
Arrow mark (0 ....... 0indicates
increase in diaphragm diameter.

II Summary of Putting the Microscope into Operation II
MODEL BHTU
A. Match the voltage selector switch to local mains voltage (page 9).
B. Switch on the light source (page 9).
C. Place aspecimen slide on the mechanical stage.
O. Coarse focus with the lOX objective.
E. Make interpupillary distance and diopter adjustments (page 12).
F. Adjust the condenser position (page 13).
G. Swing in the desired objective.
H. Adjust light intensity.
I. Fine focus.
J. Adjust aperture iris diaphragm and field j'ris diaphragm ~page 13).
I Adjustment of Illumination System for Various Objective Powers II
Condenser
Objective Achromatic-
aplanatic Abbe Swing·out
Low power
magnification condenser
condenser condenser condenser
BH2-AAC BH2-CD BH2-SC BH2-UL-C
lX
2X
Swi ng out top
Compatible
4X
lens
lOX
20X
Compatible
40X Compatible Swing in
top
lens
BOX
- - - - - - - - - - .-
lOOX •
*N.A. is somewhat low, but still compatible with a100X objective.
(Take acopy of this page
and put it on the wall near the microscope for use as areminder of
microscopic procedure.)
OLYMP'US®
8

v. OPERATION
A. Switching on the Light Source
1) Ascertain that the voltage selector SWitch CD
is set to conform WIth the local mains voltage.
(Fig. 3)
If the switch is not correctly set. adjust it by
means of the Allen wrench provided, or a
screw-driver.
2) Place the sliding voltage control lever on the
nght side of the microscope base to a lXlSition
dosest to you (low voltage position). Switch
on the light source (ma;n SWitch (2)1. (FIQ. 3)
,.
Fig. 3
IVoltage Adjustment and Ugh! IntensityI
As you push the control lever (j) in the direction
of the ARROW. the voltage increases. and the
LED readout (2) \¥ill display the lamp voltage.
(Fig. 4)
IlP (light Intensity Presening) Switch
Apart from the light intensity set by voltage
adjustment control lever, the
LP switch can set
the light intensity as required.
Presetting the light intensity (Fig. 5)
1) Switch ON the LP switch CD.
2) Insert aslotted screwdriver into me LP adjust~
ment screw (1). Turning it clockwise will in-
crease the light intensity. Turn it until required
intensity is obtained.
*The light intensity will not change even
if the voltage adjustment lever @ with
the LP switch ON. To change the light
intensity by using the voltage adjustment
lever, switch the
LP switch OFF. To recall
the
light intensity preset, push the LP
switch to ON.
AHint on Convenient Application of the LP
Switch
For instance, when you want to use two kinds of
objective lens ahernatley. set one objective by using
the vohage adjustment
[ever. then set another
objective lens by using the LP switch. This allows
the ffght intensity 10 recallhe intensity initially preset
by switching the LP swilch ON and OFF.
This also allows the light intensity setting for
photomicrography.
9
Fig. 4
Fig. 5

. ..
.~~
~~ .... - ~ /~-"'"'"
Fig. 6
B. Placement of a Specimen Slide
11 Rotate the coarse adjustment knobs CD in the
direction of the ARROW to rack down the stage
so that aspecimen slide can be placed on the
stage.
(Fig. 6)
NOTE: The rotation of the coarse and fine
adjustment knobs in the direction of the
ARROW will rack down the stage.
2) Opening the spring-loaded finger of the speci-
men holder with one hand, place aspecimen
slide Inside the holder
with the other hand.
When the slide comes
in contact with the back
of the specimen holder, slowly return the spring-
loaded finger.
WARNING: If the spring-loaded finger
IS re-
turned t.oo quickly, it may cause
damage to the specimen slide.
3) For use of the specimen holder B2-HL2
Aspecimen slide can be easily slipped into the
specimen holder by single hand operation. (Fig.,
71
Fig. 7
White Cover for Condenser
The white cover for condenser CD should be
covered over the condenser. (Fig. 8)
•When setting stain specimens under the
specimen holder, the white cover for condenser
comes into field
of view as abackground. This
allows easy distinction what you are observing
between its background.
10

ICover Glass I
•An Olympus objective engraved "16010.17" requires acover glass of 0.17mm thickness.
If the numerical aperture of the objective is 0.7 or higher (except immersion objectives)
and no correction collar is provided, the resolving power deteriorates greatly, if cover
glass thickness deviates from the above listed value.
NOTE: In some countries a0.17 mm thick cover glass corresponds to a#1 Y, cover glass.
• A cover glass (0.4 mm thick) for blood counting, etc. can be used with Olympus objectives
except 0Plan
40X. SPlan Apo 40X and SPlan lOOX.
ISpecimen Slide I
•Specimen slides 0.8 mm to 1.5 mm thick are
recommended for
Olympus objectives.
•Specimen slides 0.8
mm to 1.2 mm thick are
recommended for, the
dark field condenser
and the
dj fferential interferencecontrast con~
denser.
3) Bring the portion of the specimen to be
observed into the light path by means of the
low drive stage control knobs. (Fig. 9)
*Tighten the stage clamping screw <D .
I Stage I
• The specimen holder can accommodate two
standard specimen slides simultaneously.
•The specimen holder
is removalbe to obtain
alarge unobstructed stage surface to hold
specimens up
to 55 mm x 85 mm.
•
To rotate the stage loosen the $tage clamping
screw
CD and holding this screw, rotate the
stage into the desired direciton. (Fig. 10)
@Stage clips for use with immersion objectives.
(Fig. 111
Apair of stage clips is optionally available
to hold the specimen
on the stage, elimina-
ing specimen drag or buckling due to immer-
sion
oil between slide and stage surface. The
cI ips can be inserted into the holes CD
provided on the specimen holder.
11
Fig.10
Fig. 11

c. Observation Tube
1. Interpupillary Distance Adjustment
1} Click the lOX objective into position.
2) Looking through the eyepieces with both
eyes, adjust the interpupillary distance of
the binocular tube by adjusting the
knurled dovetail slides
CD of the right and
left eyepiece tubes with b9th hands until
perfect binocular vision is obtained. {Fig.
121
-
Fig. 12
2. Diopter Adjustment
1) Looking at the image through the right
eyepiece with your right eye, focus on
the specimen
with the fine adjustment
knobs.
21 Next, looking at the image through the
left eyepiece with your left eye, rotate
the
diopter adjustment ring CD to focus
on the specimen
without using the
coarSE and fine adjustment knobs..
(Fig.
131
3. Light Path Selection
1) The trinocular tube is provided with a
light path selector lever CD to direct the
light to the observation tube and/or to
the photo tube in 3positions. (Fig. 141
Indicator Plate
~J ./11
tii - ,,~
&,~ :t \'i~
, 1lIII\,'
~ _f'~"
~ .~ -.:.$
[1 '
Fig. 14
CD
r
Lever Position
Pushed
in all the way
Pulled out: halfway Pulled out all the way
(VI
(C. 11.1
(C)
Amount
100% into binocular tube 20%
into binocular tube 100%
into photo tube
of light
80% into photo tube
CD Observation
CD Observation of exces- Photomicrography
of
Applica·
sively bri~lht specimens
dark specimens
CV Dark specimens
~ Photomicrography (fo·
tion
cusing through the bi-
nocular tube)
An indicator plate is provided at the knob port to summarize the usage of the above table;
it can be consulted before operating the knob
V: Viewer (white letters)
CV: Camera &viewer (yellow-green letters)
C: Camera (red letters)
The colors of the letters correspond wi th the color bands on the knob shaft.
12

D. Condenser Adjustment
®
Fig. 14
Fig.
15
1. Condenser Centration
1) Stop down the field iris diaphragm with
knurled ring CD by rotating in the direc-
tion of the arrow. (Fig. 14)
2) Use
the condenser height adjustment
knob ® to move the condenser up and
down until an image of the field dia-
phragm can be seen clearly in the eye-
pieces. The rotation of the knob in the
direction of the arrow lowers the con-
denser.
Field iris
diaphragm image Field of view
3) Bring the field iris diaphragm image into the center of the field of view with the two con-
denser centering knobs ®. (Fig. 14)
4) Widen the diameter of the iris diaphragm progressively. If the polygonal image of the iris
diaphragm becomes inscribed in the field it means that the field diaphragm is centered.
(Fig.
15)
Field Iris Diaphragm I
• The field iris diaphragm controls the diameter of the ray bundle impining on the speci-
men surface and therefore, by stopping down the field diaphragm until it is slightly
larger than the field of view, it can reduce stray light, which in turn increases image defi-
nition and contrast.
70-80%
20 -30","
Fig. 16
Opening of the
aperture diaphragm
Objective
exit pupil
Aperture Iris Diaphragm I
•In order to achieve opTimum objective performance, the opening of the aperture iris
diaphragm should be matched
to the numerical aperture of the objective in use. It is
often preferable, however, to stop down the aperture diaphragm slightly more than in-
dicated
by the objective N.A. This will result in better image contrast, increased depth of
focus and a flatter field.
• After completing focus adjustment, re-
move one
of the eyepieces from the ob-
servation tube and look into the empty
eyepiece tube. As you stop down the
aperture iris diaphragm, the image of the
iris diaphragm can be seen in the object-
ive pupil. Adjust the opening of the
diaphragm to match the N.A. of the ob-
jective in use. If the specimen is low in
contrast,
it is recommended to stop down
to 70% - 80% of the objective N.A. (Fig.
161
13

EFocus Adjustment
Fig. 18
f
Adjustment Knobs and
Although the tension of the coarse adjust-
ment knobs
has been already adjusted for
optimum performance by the manufacturer.
it
is possible to personally adjust the tension
of the coarse adjustment for either heavy or
light movement depending
on the operator's
preference by rotating
the tension adjust-
ment ring <D. (Fig. 181
The ring can be rotated by inserting ascrewdriver into one of the holes on the periphery of the
ring. The clockwise rotation (in the direction of the ARROW) tightens the coarse adjustment
knobs. Do not loosen the ring too much, because the stage may drop or the fine adjustment
knobs may slip.
CD
1. Tension of Coarse
Fine Adjustment.
NOTE: Do not rotate the right and left coarse adjustment knobs in the opposite directions
simultaneously. If the
stage drops and the specimen goes out of focus. the tension
adjustment
ring is too loose. Tighten the ring.
Use of Rubber Cap for Fine Adjustment Knob,
Attaching this
cap over the fine adjustment
knob
increases the sensitivity of the fine focus-
ing motion. (The rubber cap is optionally
available.)
2. Pre-Focusing Lever
This lever ill is provided to prevent possible
contact between specimen and objective as
well as to simplify coarse focusing. (Fig. 191
The lever is locked after coarse focus has
been accomplished. This prevents further
upward travel
of the stage by means of the
coarse adjustment knobs, and automatically
provides alimiting stop if the
stage is lowered
and then raised again. The pre-focusing lever
does not restrict fine focusing.
Fig. 19
14

F. Use of Immersion Objectives
1) Focus the specimen with a low power objective.
2) Put a drop of immersion oil on the specimen slide and the front lens of the immersion
objective.
3) Rotate the revolving nosepiece to bring the immersion objective into the light path, and
focus with the fine adjustment knobs.
NOTE: ill For immersion condensers such as an achromatic-aplanatic condenser or Abbe
condenser, remove the specimen from the mechanical stage and place a drop of
immersion oil on the front lens of the condenser. Then, place the specimen on
the stage and slowly raise the condenser until firm contact with the underside of
the specimen slide is made.
®Care should be taken to prevent oil bubbles from forming in the oil film between
condenser and specimen slide.
If any bubbles appear, re-apply immersion oil,
for these bubbles greatly deteriorate the lens performance.
® After use. carefully wipe off the immersion oil deposited on the lens surfaces
with gauze moistened with xylene. Never leave oil on the lens surfaces after use
as oil remnants will seriously impair the perforrrance of the lens system.
,
G. Photomicrography
The
Olympus Photomicrographic Equipment Model PM-lOAO is uniquely qualified to be
used with the BHTU microscope for routine and advanced photomicrography. Aseparate,
detailed instruction manual
is available for the PM-lOAD camera system.
For quick reference, however, you may want to refer to the following pointers when using
the PM-lOAD.
1. Photographic Eyepiece
Use NFK photo eyepieces for photomicro-
graphy.
Insert
the eyepiece CD into the eyepiece tube
of the photo tube. (Fig. 20)
Fig. 20
2. Mounting the Photographic Unit
Slip the body of the photographic unit over the
photo tube. Align the dots on photo tube and
the PM- lOAD body and clamp the camera unit
to the photo tube. (Fig. 211
3. Setting the Light Path Selector
Refer
to section C.3. on page 12.
15

Fig. 22
4. Focusing Procedure
Use the field of view eyepieces for focusing on the film plane. Each field of view eyepiece
has afocusing front lens and a relide with 4frames, each frame indicating the area covered
by aspecific power NFK photo eyepeice. (Fig. 22)
The number at each frame indicates the
magnification
of the photo eyepiece. The
image in
the field of view eyepiece and the
image on the film plane are in focus at the
same time. Several type field of view eye-
pieces are available, according to the film
size employed.
Field
of view eyepiece 35WHK10X PWHK10X
4X5WHK10X
MHWHK10X
35mm Back 3%" x 4%"
4" x 5" 16mm Bolex
Attachment camera Polaroid Sheet Film or camera
Back Polaroid Film 120 Roll Film
Holder Holder
1) Select the field of view eyepiece matching the camera bSlck in use and insert it into the
right eyepiece tube
of the trinocular tube, aligning locating groove and locating pin.
2) While
looking through the field of view eyepiece, rotate the eyepiece front lens in screw
mount to focus on the double cross lines in the field. For sharp focusing with objectives
4X or lower, the focusing magnifier FT is recommended on account of their considerable
depth
of focus.
3) Bring the specimen detail to be photographed within the frame corresponding to the
power
of the NFKeyepiece in use and focus on the specimen with the microscope fine
adjustment knobs. Make sure the
light path selector knob on the observation tube is
either on the white (V) or yellowijreen (eVI band.
4) It is recommended to tighten the tension adjustment ring considerably to prevent the
stage from dropping during long exposures.
16

VI. OPTICAL DATA
Objective
Type
o Achromat
oPlan Ach.
Magnifi-
4X lOX 40X l00X'
4X lOX 40X
100X'
cation
N.A.
0.10
0.25 0.65
1.30
0.10
0.25 0.65
1.25
W.O. (mm)
18.2 7.2 0.6 0.20
7.03
7.4 0.27
0.17
Focal length
30.03 16.9 4.58
1.91
34.23 17.5
4.67 1.75
lmml
Eyepiece Resolving
3.36 1.34 0.52
0.26
3.36 1.34 0.52
0.27
power (jJ)
WK10X
Total mag. 40X 100X
400X 1000X
40X
100X
400X
lQOOX
(Field
Focat
171.6 27.45 3.0 0.7
171.6 27.45
3.0
0.7
number depth
{jJJ
201 Field
of
5 2 0.5 0.2
520.5
0.2
view (mm)
ll-Immersion objectives
The resolving power and focal depth are obtained
witt' fully opened aperture diaphragm.
Technical terms:
•Working distance: The distance from the cover glass to the nearest point of the
objective.
•Numerical aperture: The N.A. represents aperformance number which can be com-
pared to the relative aperture (f-number) of acamera lens. Th~
N.A. values can be used for directly comparing the resolving
powers of all types of objectives. The larger the NA. the higher
resolving power.
• Resolving power: The ability of a lens to register small details. The resolving power
of a
lens is measured by its ability to separate two points.
•Focal depth: The distance between the upper
and lower limitsof sharpness in
the image formed by an optical system. As youstop down the
aperture
iris diaphragm, the focal depth becomes larger. The
larger the N.A. of an objective the shallower the focal depth.
•Field number: Anumber that represents the diameter
in mm of the image of
the field diaphragm that is formed by the lens in front of it.
•Field of view diameter: The actual size of the field of view in mm on the object surface.
17

VII. TROUBLESHOOTING GUIDE
If you are unable to obtain full performance from your microscope, please consult with the
table below as pointers for troubleshooting.
Phenomenon Cause
Remedy
1. Optical System
a)
With illuminator switched
Field iris diaphragm
IS
not
Open
diaphragm
to
proper
on, the field
of
view is
opened sufficiently. diameter.
dark. Condenser
is lowered
too
Adjust condenser height.
much.
Light path selector lever
is
Push in lever
up to CV or V
pulled
out to Cposition.
position.
b) Field
of view is cut off or
Light
path selector lever
is
Click
it into proper position
illuminated irregularly.
stopped midway. according to your
purpose.
Nosepiece is not clicked
into
Slightly rotate nosepiece until
place. it cl icks into place.
The power of objective used Choose acondenser
to
meet
exceeds
the illu'mination
ca-
your purpose.
pacity of condenser.
Condenser is
not centered. Center condenser.
Field
irisdjaphragm is stopped Open diaphragm to
proper
down excessively. diameter.
c)
Dust
or dirt is visible
In
Dust, etc. on light
exit lens Remove
dust, etc.
the field of view.
Dust on condenser top lens Clean
front tenses.
Dirty specimen
Dust on eyepiece
d) Excessive image contrast Condenser
is lowered
too
Adjust condenser height.
much.
Aperture iris diaphragm
is
Open diaphragm to
proper
stopped down excessively. diameter.
18

Phenomenon Cause
Remedy 1
el Resolution problems:
LB
objectives other than
Use Olympus LB series objec-
series are used. tives.
•I
mage is not sharp. objectiv8
not
correctly
Click nosepiece into place.
I
IS
•
Insufficient contrast. positioned in
the light path.
•Image details lack defi-
nition.
Objective correction collar is
Rotate correction collar, keep-
not adjusted correctly.
ing specimen in fine focus
until
optimum resolution
is
obtained.
Dust on objective
front lens Clean
front lens.
Immersion objective
is not
Use immersion oil.
used with immersion oil.
Bubbles in immersion oil Remove bubbles (and reap-
ply oil).
Immersion oil designated by
Use Olympus
immersion oil.
Olympus is not w~ed.
Dirty specimens Clean.
Dust on condenser
lens
fl
Field
of view is partially
Objective
is
not correctly
Slightly rotate nosepiece until
out of focus, or image is
positioned in the light path. it clicks in place.
partly out of focus. Specimen
is
not correctly
Place specimen slide correctly
positioned on stage. on stage, and place
stage clips
open it.
gl Specimen image
is partial- Objective
is not correctly
Slightly rotate nosepiece until
Iy out of focus. positioned in the
light path.
it clicks into place.
Condenser
is not centered. Center condenser.
h) Field of
view becomes Condenser
is not
correctly Center condenser.
only slightly
brighter by
centered.
increasing voltage. Condenser
is lowered too
Adjust condenser height.
much.
2.
Electric System
al
Illuminator is too bright
Line voltage selector switch Match selector switch
to
(or too dark)
even when
is not matched with local mains voltage.
adjusting
control lever. mains voltage.
b)
Voltage for illuminator
cannot be raised.
cl Lamp
goes off and on. Bulb
filament is
likely
to
Replace bulb.
burn out.
Loose electric connections. Check all connections.
d)
Bulb burns out frequently.
Line voltage selector switch is
Match selector switch to
not matched with local mains mains voltage.
voltage.
Bulb
is not standard one.
Use standard bulb.
19