Shutter Assembly Troubleshooting

TM 11-6720-239-35

Corrections

Symptom

Probable trouble

Blade stays open on all speeds except

Replace capacitor C2.

Defective capacitor C2 . -. ---------

3000 when lighting selector control

is set to left (dull) position.

150 Dull very fast, on 75 Dull one stop

Repair connection between affected con-

Open circuit between positive (+) C2

fast.

tacts.

contact and selector switch (S5), C2

contact.

Clean switch rotor and contacts, adjust

Dirty or defective selector switch S5 --

contacts to touch rotor.

Replace capacitor C2 (para 3-6).

Defective capacitor C2 .. . . . .

Adjust potentiometer R3 or replace photo-

Incorrect trigger voltage -- . . . . .

All speeds either too fast or too slow. -.

cell V1 or both. (para 3-19 and 3-20).

FILM SPEED dial of aperture wheel

Adjust S2 (para 3-19).

Switch S2 out of adjustment-

Replace blades. (para 3-6).

150 or 300 dull too fast or too slow

Mechanical binding of blades --------

Lubricate cocking slide with lubricating wax.

or erratic.

Mechanical binding of cocking slide---

Clean magnet and keeper.

Rust or foreign matter on magnet or

keeper.

Clean S6 contacts with fine file.

Dirty switch S6 contacts .- -.

String jumper wire between affected con-

75 dull too fast, all other speeds

Open circuit between positive (+) C3

tacts.

normal.

contact and selector switch (S5) C3

contact.

Defective capacitor C3 ----------

Replace caparitor C3 (para 3-6).

Clean and adjust S4 contacts.

Open Contact between S4 center con-

tact and S4 contact connected to R4.

Open circuit in selector switch S5

Clean and adjust switch S3 contacts.

between C3 contact and common

contact.

75 dull too slow . . ___

Defective

capacitor

C3__

Replace capacitor C3. (para 3-6).

Defective capacitor C1 ___

3000 dull too fast or too slow- ----

Replace capacitor C1. (para 3-6).

Replace Photocell V1. (para 3-6).

Defective

Photocell

--------

Blades close together on 3000 dull

Resolder capacitor C1.

C o l d - s o l d e r e d capacitor C1 -------

Defective capacitor C1 __--

only.

Replace capacitor C1. (para 3-6).

Dirty or maladjusted switch S6 _

F-stop meter does not repeat within

Clean and adjust switch S6.

±0.15 F-stops after inserting and

removing flash plug.

Defective or cold-soldered resistor R4

F-stop meter varies from specified ¼

Replace or resolder resistor R4 or R7, or both.

to ½ inch rise with flash plug

or R7.

inserted.

Flash test bulb does not fire_ .

String jumper wires between flash safety

Open connection in flash circuit-

switch and outside contact of flash jack

or between flash switch SX and inside

jack, or both.

contact

Clean or replace flash switches S3 and/or S4

Dirty or defective flash switches S3

as required.

and or S4.

Adjust potentiometer R3 or replace

Incorrect trigger voltage _____

75/50 dull does not conform to

photocell, or both, (para 3-19).

specifications.

a. Replace C2 or C3 (para 3-6).

75/50 dull 15 only one stop fast

a. Defective capacitor C2 or C3 --- .

b. String jumper wires between C2 or C3

b. Open circuits between C2 or C3 and

and their respective S3 contacts on

their respective S3 contacts on

switch S5.

light selector switch S5.

Replace capacitor C4. (para 3-6).

75/50 bright and 75/300 bright too

Defective capacitor C4 .. ---- ___ -----

fast or too slow.

Replace capacitor C4. (para 3-6).

75/50 bright and 75/800 bright too

a. Defective capacitor C4 _- --- ______

String jumper wires between positive (+)

fast only.

b. Open circuit between positive (+)

side of C4 and its contact on switch S5.

side of C4 and its contact on

light selector switch S5.

75/800 dull too fast or too slow --------

Adjust timing switch S2. (para 3-19).

Timing switch S2 out of adjustment_ ---

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