TM 55-4920-244-14
104.
76.
Lampholder
Seal Screw
49.
Printed Circuit Board
105.
Seal Screw
77.
Lamp
50.
Screw
Nut
106.
78.
Connector
51.
Washer
Dust Cover
107.
79.
Connector Mount
Nut
52.
108.
80.
Screw
Screw
53.
Spacer
109.
Gasket
Washer
54.
81.
RPM Check Assembly
110.
Connector
82.
55.
Knob
Seal Screw
111.
Connector Mount
83.
Boot
Seal Screw
56.
112.
Screw
84.
Nut
57.
Screw
113.
Washer
85.
Dust Cover
58.
Nut
114.
Seal Screw
86.
59.
Screw
Lockwasher
115.
Seal Screw
87.
Gasket
Knob
60.
116.
Nut
88.
Connector
Potentiometer
61.
117.
Dust Cover
89.
Connector Mount
Screw
62.
118.
Screw
90.
Washer
63.
Screw
119.
Gasket
91.
Washer
Spacer
64.
120.
Seal Plate
92.
65.
Seal Screw
Seal Plate
121.
Seal Screw
93.
66.
Seal Screw
Seal Screw
122.
Nut
Nut
94.
67.
Nut
123.
Packing
Dust Cover
95.
68.
Packing
124.
Stop Arm Support
96.
69.
Galvanometers
Gasket
125.
Screw
98.
Switch
70.
Seal Screw
126.
Screw
99.
71.
Boot
Nut
127.
Window
100.
72.
Connector
Gasket
128.
Machined Deck
101.
Connector
73.
102.
74.
Screw
Fuse
103.
75.
Washer
Fuse
Figure 4-8-Continued
(3) Loosen setscrew and remove
(2) Remove meter from deck as far
knob (18) from potentiometer.
as attached wiring will permit. Identify and tag
(4) Remove seal nut, which secures
wiring. Provide several thicknesses of cloth or
potentiometer to deck (128). Remove potentiom-
other cover for top of deck.
eter.
(3) Unsolder and remove wiring
from rear of meter. Remove meter (39).
b. Disassembly. No disassembly is re-
b. Disassembly and Repair. No disassem-
quired.
bly or repair is necessary. Replace on an as re-
c. Cleaning.
quired basis.
(1) Clean exterior of potentiometer
with cloth or soft brush.
4-23. Potentiometer (R-1) (Figure 4-8).
(2) Remove any foreign matter with
The potentiometer (13) is a wirewound,
a cloth dampened with dry cleaning solvent
continuously variable potentiometer with a value
(item 1, table 1-1).
of 0 to 50 ohms. The potentiometer is used in de-
termining error in the EGT indicator circuit of
d. Inspection and Testing.
the aircraft system. Resistance tolerance of the
(1) Inspect terminals for corrosion.
potentiometer is + 5 percent and variation from
(2) Inspect case for cracks or other
linear adjustment tolerance is + 0.3 percent.
damage.
(3) Rotate shaft to one extreme of
a. Removal.
its travel.
(1) Remove deck assembly (para. 4-
(4) Rotate shaft to other extreme of
32).
its travel, counting number of turns necessary to
(2) Identify and tag wiring. Unsol-
complete travel. Ten complete turns should be
der and remove wiring from rear of potentiome-
required, less no more than 15 degrees.
ter (13).
4-21
