OPTICAL SYSTEM.

ARMY TM 9-6650-235-13&P

MARINE CORPS TM-08552A-13&P

(1) General. The marking of optical elements

c. Marking Parts During Disassembly. As each

part is removed, it may be necessary to return that part

has a double purpose. It aids in the assembly of the

to its exact original position. Its exact position, in relation

instrument by indicating the original position of the

to the assembly, should be established by making

element in relation to other elements.

reference marks. Never make marks on threads or

(2) Lenses. The prime purpose for marking

bearing surfaces. Optics may be marked as specified in

lenses upon disassembly is to establish a guide by which

paragraph 5-10.

the lenses can be assembled in their proper relative

d. Removal of Burrs. Movable components of the

position. This mark should consist of a "V" inscribed on

M3 Borescope must operate smoothly. Small burrs can

the uncoated surface (edge) across all the elements of a

be removed with a knife-edge oilstone. If the burr is

compound lens. The point of the "V" should be directed

larger, a jeweler's file can be used to reduce it until it is

toward the cell when assembling. The marking can be

practicable to use an oilstone. Clean parts after filing or

done with an indelible pencil. In addition, the lenses

honing, taking care to remove all metal particles and

should be lettered and numbered to indicate the

abrasives and install the component in the assembly.

assembly and the sequence in which they are placed in

the instrument. For example: eyepiece assembly should

e. Conversion of Decimals to Fractions. See

be marked with an "E". Optical instrument lenses should

appendix G for converting decimal measurements into

be marked "1", optical instrument field lenses "2", etc.

fractions.

The numbering system aids in preventing improper

replacement of the lenses that are similar in appearance

and easily mistaken for each other.

5-10. OPTICAL SYSTEM.

5-11. ELECTRICAL SYSTEM.

a. Installation of Lenses. It is very important that all

lenses in the M3 Borescope are properly installed. Refer

to figure 5-1 (page 5-11) for the M3 Borescope optical

a. Schematic Diagrams. Figure 5-3 (page 5-13)

and figure 5-4 (page 5-14) are schematic diagrams of

system. Ensure the lenses are facing the proper direction

the electrical system of the M3 Borescope. Refer to the

during reassembly.

schematic diagram to ensure proper connection of the

wiring during reassembly of the individual assemblies of

CAUTION

the M3 Borescope. Figure 5-2 (page 5-12) is a schematic

Never touch the coated surface of

diagram of the 115-V electrical power cable assembly

optics.

and the 24-V electrical power cord adapter assembly.

b. Handling Optics When Removed. When optics

b. Internal Wiring. All internal electrical wiring in

are to be laid aside, each must be wrapped in a piece of

the M3 Borescope is 18 gage. If a wire is damaged, refer

lens paper (item 10, app D). When storing optics, always

to the maintenance instructions for the respective

clean and wrap them completely in lens paper (item 10,

component. Instructions for fabricating new wire are in

app D).

appendix E.

c. Marking of Optical Elements.

c. External Wiring. The 24-V electrical power cord

adapter assembly and the 115-V electrical power cable

5-9