Table 2-3. Troubleshooting - TM-11-6130-429-400043

TM 11-6130-429-40

Table 2-3. Troubleshooting-Continued

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

Step 5. Soft Start, Overvoltage + Current Limit Circuits (P/O A1 PCB) Check (fig. 2-6).

a. Using voltmeter, check for +4 0.4 Vdc between U2-9 and U2-12 (-), and +2.5 Vdc between U2-8 and U2-12 (-).

Check components associated with soft start circuit/replace defective components.

b. Using scope (1V/Div), check for +0.8 to +0.9 Vdc between U2-6 and C1 (-) and +2.5 0.1 Vdc between U2-7 and C1

(-).

Check components associated with overvoltage circuit. Replace defective component. Adjust OV/UV potenti-

ometer R56.

c. Using scope (.1V/Div), connect 1:1 probe between U2-4 and C1 (-). Adjust scope as required to observe display as

shown in figure 2-8C.

Turn OFF equipment and disconnect test cable. Using multimeter check continuity between E8 of A2 PCB to

cathode of CR14 on A1 PCB and E9 of A2 PCB to anode of CR11 on A1 PCB. Check associated components on

A1 and A2 PCB. Replace defective components.

d. Using voltmeter, check for +0.35 to 0.85 Vdc between U2-5 and U2-12.

Check associated components. Replace defective component.

Step 6. Drive Circuits From U1 to 20 KHz Switching Converter (P/O A1 PCB Check).

a. Using scope (2V/Div) connect 1:1 probe between U 1-11 and C 1 (-), and then between U1-11 and C1. Adjust scope as

required to observe display as shown in figure 2-8D.

Check Q5, Q6, Q7, Q8, Q9, Q10, Q16, Q17, and associated components. Replace defective components.

b. Connect scope probe between CR2 anode and C1 (-). Adjust scope as required to observe display as shown in figure

2-8E. Repeat procedure between CR9 anode and C1 (-).

Check associated drive circuit. Replace defective component.

c. Connect scope probe between J2-4 and C1 (-). Adjust scope as required to observe display as shown in figure 2-8F.

Repeat procedure between J2-11 and C1 (-).

Check associated drive circuit. Replace defective component.

d. Connect scope (1V/Div) probe to Q8 collector (case) and scope ground to C7 (-). Adjust scope as required to observe

display as shown in figure 2-8G. Repeat procedure between Q10 collector and C7 (-).

Check associated drive circuit. Replace defective component.

e. Set variable load RANGE switch to 18A. Set load adjust for 2 A. Check for +5.1 to 5.6 Vdc between J1-5 (+) and J1-17

(-).

Repair wiring.

Step 7. Undervoltage/Overvoltage Detection Circuits (P/O A1 PCB) Check.

a. Using voltmeter, check for +2.7 to 2.85 Vdc between U8-1 and U8-6.

Check associated components. Replace defective component/replace U8.

b. Check for +5.3 0.2 Vdc across R60.

Turn OFF all equipment and remove test cable. Check wiring from J1-16 to rear panel P1-A6. Check C17,

CR20, R59, R60, R85, R86, and U3. Repair wiring/replace defective component.

c. Connect voltmeter between front panel +5V RTN (TP1) and +5V P1 (TP4). Loosen locking nut on +5V ADJ and slowly

adjust potentiometer clockwise. Observe when voltmeter reading nears +6.1 to 6.5 Vdc, FAULT lamp lights, and

voltmeter reading drops to less than +2 Vdc.

Check wiring from J1-15 to gate of Q7. Check C8, CR19, CR23, CR24, R51, R53, R54, R55, and U3. Repair

wiring/replace defective component.

d. Turn converter ON/OFF switch to OFF. Turn +5V potentiometer fully counterclockwise and turn converter ON/OFF

switch to ON. Adjust +5V until voltmeter reads +4.9 to 5.1 Vdc. Remove voltmeter leads from TP1, TP4, and connect

to C8 (-) and junction of R46, R47, and observe reading of +3.08 to 3.67 Vdc.

Check Q12, Q13, and associated components. Replace defective components.

Step 8. Secondary Regulator Loop Circuit (P/O A1 PCB) Check.

a. Set variable load RANGE switch to 60A and adjust +5V potentiometer on front panel until voltmeter reads +4.98 to

5.02 Vdc and tighten locking nut. Connect voltmeter between U9-6 and U9-7 (+); observe indication of +3.047 to 3.121

Vdc.

Check U3, U9 and associated components. Replace defective component.

b. Using voltmeter, check for +3.047 to 3.121 Vdc between U3-1 and U3-10 (+).

Check wiring from J1-12 on A1 PCB to P1-A4 on rear panel. Check U3-D and associated components. Replace

defective component.

c. Turn equipment OFF. Connect equipment as shown on figure 2-9. Connect the jumper between P2-A3 and P1-A3 on

test cable. Connect a 0-1 amp power supply to P1-A6 and P1-A3 (+). Connect voltmeter to TP1 and TP4 on front panel.

Turn ON input power supply and converter. Turn ON 0-1 amp power supply and adjust voltage until voltmeter reads

+5.5 Vdc. Connect voltmeter between TP2 (+) and TP1 (-) on front panel, and observe reading of +5.069 to 5.192 Vdc.

Check U3B, Q15, and associated components. Replace defective component.

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