Table 6-2. Internal and External Card Test Circuit Troubleshooting.

C1, TM 11-6625-646-15

b. Remove the bottom pan from the chassis.

Install a replacement valve with a new gasket.

c. Remove the two card retainers.

Connect the plumbing to the valve.

d. Carefully withdraw the seven component (plug-

Install the bottom pan on the chassis.

in) cards from their receptacles.

Reinstall the chassis in the case.

e. Disconnect the tube assemblies from the gage.

f. Remove the attaching hardware and withdraw

6-9. Replacement of Tube Assemblies

the gage from the panel. Retain the hardware.

Replace a tube assembly as follows:

g. Install a replacement gage in its mounting hole

a. Remove the chassis from its case.

in the panel.

b. Remove the bottom pan from the chassis.

h. Connect the tube assemblies to the air gage.

c. Replace the tube assembly and associated

i. Reinstall the seven component cards in their

fittings. (Refer to TM 55-405-7 for detailed instructions

respective receptacles. Make certain that each card is

on fabricating tube assemblies.)

in its proper position.

d. Install the bottom pan on the chassis.

j. Align the cards and install the two card

e. Reinstall the chassis in the case.

retainers.

k. Install the bottom pan on the chassis.

6-10. Replacement of Air Gages

l. Reinstall the chassis in the case.

Replace an air gage as follows:

a. Remove the chassis from the case to gain

access to the gage.

Table 6-2. Internal and External Card Test Circuit Troubleshooting.

Trouble

Probable cause

Remedy

Function meter M1 does not indi-

No test signal available at pin 6

Replace component card

cate in the red area; FUNC-

of J71.

A02V3064. If this does not

TION switch at AMPL OUPT

correct the trouble, reinstall the

and CARD TEST SIGNAL

original card; troubleshoot the

switch S6 operated to L or R.

wiring to J67-13 and the wiring

to S6.

Defective internal ac power supply

Check for 26 volts ac at pin 18 of

J67. If 26 volts ac is not present,

troubleshoot the ac power supply.

Check for 27 volts dc at pin 7 and

Troubleshoot the B+ and reference

for 8 volts ac at pin 19 of J71.

voltage circuits.

Faulty wiring in the metering

Troubleshoot the circuits between

circuit or defective FUNCTION

pins 13, 15, and 17 of J71 and

switch.

pins 7, 8, and 9 of J67.

Troubleshoot the circuit from

pin 10 of J67 to FUNCTION

switch S7. Repair wiring as re-

quired. If switch S7 is defective,

replace it.

Resistance between pins 1 and 7

Defective wiring or defective

Repair wiring or replace resistor

of J70 is not 100K ohms 5%.

resistor R205 on component

R205.

card A02V3060.

Ac voltage between pins 12 and

Defective internal power supply

Check for 115 vac between

18 of J70 is not 26 vac.

MAIN CONNECTOR TEST

POINTS i and C. If voltage is