(5)  
Set dc selector switch to TR 1. 

(a)  
Check that voltmeter indicates 26 + 4 volts.

(b)  
Check that ammeter indicates load is present.

(c)  
Check that NO 2 and TR3 lights on M238 do not come on.

(6)  
Close DC BUS POWER NO 2 (C27) and DC BUS INDICATION BUS NO 2 (C24) circuit breakers. Check that NO 2 and TR3 lights on M238 do not come on.

(7)  
Open TR UNITS NO 1 (C806) circuit breaker and check that NO 1 light goes out and that the voltmeter and ammeter read zero.

(8)  
Check that TR UNITS NO 2 (C807) circuit breaker on P6-4 and TRANSFER BUS NO 2 NORMAL (C821) circuit breaker on P6-12 are closed. Check the following:

(a)  
NO 1 light on M238 remains out.

(b)  
Voltmeter indicates zero (selector switch set to TR 1).

(c)  
NO 2 light on M238 illuminates.

(9)  
Set dc meters selector switch to TR 2.

(a)  
Check that the voltmeter indicates 26 + 4 volts.

(b)  
Check that the ammeter indicates a load is present.

(10)
Open TR UNITS NO 2 (C807) circuit breaker on P6-4.

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(a) Check that NO 2 light on M238 goes off and the voltmeter reads zero.
E.  Test No. 3 TR Unit/Battery Bus Transfer Circuits and Control
NOTE:  To obtain an indication from the M238 module, place IND-TEST switch (S2) in IND position.
(1)  
Check that BUS TRANSFER switch is set to AUTO.

(2)  
Close TR UNITS NO 3 (C808) circuit breaker on P6-4.

(a)  
Check that NO 1, NO 2, and TR3 lights on M238 come on.

(b)  
Check that dc voltmeter reads 26 + 4 volts when dc meters selector switch is set to TR 1, TR 2, and TR 3.

(3)  
Set BUS TRANSFER switch to OFF.

(a)  Check that NO 1 light on M238 goes off.

(4)  
Open TR UNITS NO 3 (C808) circuit breaker on P6-4.

(a)  
Check that TR3 and NO 2 lights on M238 go off.

(b)  
Check that BATT light on M238 remains on.

F.  Test External DC Power
(1)  
Connect external dc power to battery control shield per placarded instructions and close EXTERNAL POWER DC (C542) circuit breaker on J9.

(2)  
Disconnect connector from airplane battery and isolate connector from structure.

CAUTION: HANDLE CONNECTOR CAREFULLY WHILE VOLTAGE IS APPLIED.

(3)  
Check that APU can be started from external dc power (Ref. 49-11-0, MP).

G.  Restore Airplane to Normal
(1)  
Remove external dc power and connect battery connector.

(2)  
Close all circuit breakers remaining open on P6-4, P6-5, and P6-6 panels.

(3)  
Set BUS TRANSFER switch to AUTO and STANDBY POWER switch to AUTO.

(4)  
Remove external power if no longer needed (Ref. 24-22-0, MP).

(5)  
Set battery switch to OFF.

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Oct 20/84  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  24-31-0 Page 503 

2.  Test DC Generation System Operation (CA B2501 thru B2503; IDO 601; NU JA8443 thru JA8475)
A.  Test Battery Control and Indicator Circuits Using Airplane Battery
NOTE:  To obtain an indication from the M238 module, place IND-TEST switch (S2) in IND position.
(1)  
Remove electrical power from airplane and set BAT switch and STANDBY POWER switch to OFF.

(2)  
Open all dc circuit breakers on P6-5 and P6-6 panels except leave the following closed:

(a)  
HOT BAT BUS (C22) on P6-6

(b)  
DC BUS INDICATION HOT BAT (C134) on P6-5

(3)  
Set dc meters selector switch to BAT and check that dc voltmeter indicates 24士 4 volts.

(4)  
Close the following circuit breakers:

(a)  
BAT BUS CONT (C145) on P6-5

(b)  
DC BUS INDICATION BAT (C26) on P6-5

(5)  
Set BAT switch to ON and check that BATT light on electrical power annunciator module M238 comes on.

(6)  
Set dc meters selector switch to BAT BUS and check that dc voltmeter indicates 24士 4 volts.

(7)  
Set BAT switch to OFF.

(8)  
Check that BATT light on M238 goes off and the dc voltmeter indicates zero. 

B.  Test Bus Protection Panel TR Unit Circuit
NOTE:  To obtain an indication from the M238 module, place IND-TEST switch (S2) in IND position.
　
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