Troubleshooting - TM-11-6625-351-350135

67. Troubleshooting

the POWER receptacle on the main

unit front panel to the AC OUTPUT

a. Introduction. T h e t r o u b l e s h o o t i n g

receptacle on the front panel of the

chart (c below) is designed to supplement

TF-248/G.

t h e equipment performance checklist in

(6) I n t e r c o n n e c t t h e i n t e g r a l p o w e r

TM 11-6625-351-12. Proceed with the

c a b l e assembly on the TF-248/G

s t e p s of the following checklist until a

to a source of either 110-125 volts

s y m p t o m of trouble appears. Take cor-

or 220-250 volts, 50-400 cps. If the

rective action to remedy the trouble before

p o w e r source is 110-125 volts ac,

proceeding with the next step.

place the 120V-240V switch on the

Caution: If operational symptoms are not

external transformer front panel to

known or if they indicate the possibility of

the 120V position. This action will

short circuits within the equipment, make

deliver nominal 117 volts ac power,

the short circuit checks described in para-

f r e e of powerline disturbances, to

graph 66 before applying power.

the test set. However, if the avail-

b. Conditions of Troubleshooting. Set Up

able power source is 220-250 volts

the equipment for the troubleshooting pro-

a c , place the 120-240-volt switch

cedure below as follows:

on the external transformer to the

(1) Remove the main unit from its in-

2 4 0 V position. This action causes

s t r u m e n t case (para 40b, item 12,

the TF-248/G to function as a 2 to

T M 11-6625-351-12).

1 stepdown ratio transformer.

(2) Remove the tuning unit under test

(7) Set the front-panel controls as di-

f r o m the tuning unit compartment

rected in the starting and calibrat-

of the main unit.

i n g procedures, TM 11-6625-351-

(3) R e m o v e the dust cover from the

12.

t u n i n g unit under test (para 64c).

C . Troubleshooting Charts.

(4) U s e the test harness to intercon-

N o t e : Perform the operations in the equipment

nect the tuning unit and the main

performance checklist (TM 11-6625-351-12) before

unit (fig. 46).

u s i n g this chart, unless trouble has already been

(5)' Use Cable Assembly, Power, Elec-

localized.

t r i c a l CX-6680/U to interconnect

(1) T F - 2 4 8 / G .

107