TTB-9-2920-225-34-1 Regulator Check Out and Repair 100 Amp 2920-00-900-7993 Download
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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