TB-9-2920-225-34-1
100 AMP REGULATOR
TECHNICAL BULLETIN; CHECKOUT AND REPAIR PROCEDURES
NOVEMBER 1981
TB-9-2920-225-34-1 - Page 13 of 70
TB 9-2920-225-34-1
Figure 2–6.
End view-model 03.
the regulator.
Table 2–2 gives the resistance
checks, and table 2–3 gives the voltage checks.
Table 2–4 is a diode substitution list.
2-7. Checkout and Repair.
a. Voltage Adjustment Rheostat (R6) (power
disconnected).
(1) Remove voltage adjustment access plug
(see fig. 2-5).
(2) Place ohmmeter test probes to terminals
of the rheostat (see fig. 2–5).
(3) Rotate rheostat. fully clockwise; reading
should be less than 5 ohms.
(4) If other readings are obtained, replace
rheostat with Vap-Air part number 26527097.
b. Transistors.
(1) Carefully remove transistors Q7, Q8, and
Q9 (see fig. 2-5).
(2) Position transistors as shown in figure
2–1 and check each separately (see fig. 2-2).
(3) If resistance
values differ from the
values shown in fig.
2–2, replace the transistor
with a new device. Q7 is Vap-Air part number
26316033–19; Q8 and Q9 are Vap-Air part num-
ber 26316033-20.
NOTE
Transistors Q8 and Q9 are identical and
can be interchanged. Transistor Q7 must
be replaced by a like item in the same
socket (see fig. 2–5).
(4) Check the mica insulating washers be-
tween the transistors and mounting plate. Replace
if cracked, broken or missing. Coat washers with
insulation compound per MIL-S-8660, NSN 6850-
00-880-7616.
c. Diode.
(1) Remove four screws holding transistor
mounting plate and move plate to one side.
(2) Place negative ohmmeter probe to the
connector side of diode D5 and D6, individually
(see figs. 2-5 and 2-9).
(3) Place positive probe to the circuit board
side of D5 and D6, individually. Meter should in-
dicate high resistance.
(4) Reverse probes. Meter should indicate
low resistance.
(5) If other readings are obtained, replace
diodes D5 and D6, NSN 5961–00–103–1519 (see
fig. 2-5).
(6) Reinstall transistor mounting plate.
2-7
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