Table 7-4. Troubleshooting Chart

TM 11-6625-255-14/TO 33A1-13-170-1

Table 7-4. Troubleshooting Chart

Corrective action

Probable Cause

Malfunction

a. Replace lamp.

a. Defective lamp I1 (DS2).

1. Line cord connected to power source,

b. Replace blown fuse with spare fuse.

b. Blown fuse F1.

and ac power switch is ON. Dial

Fuse F1 should be 1.6 ampere for

lamp does not light.

115-volt operation, and 0.8 ampere

for 230-volt operation.

c. Check strapping of T1 (para 2-4).

c. Transformer T1 (TS-723A/U and

TS-723B/U)

properly

not

strapped for line voltage being

used.

d. 115V-230V ac changeover switch

d. Set switch to correct position.

(TS-723C/U and TS-723D/U)

set to wrong position.

a. Replace blown fuse. If fuse blows

2. Function switch S4 is set to METER.

a. Fuse F2 in power supply is blown.

again, check C17, C37, and C18,

Af oscillator adjusted to deliver

Check V7,

several volts at 1,000 Hz, is con-

b. Check tubes and replace defective

b. Defective V8, V9, V10, V11, V12,

nected to METER binding posts.

tube.

V13, or V14.

Spectrum analyzer meter does not

Check contacts of switch S4.

c. Defective switch S4.

show response:

c. Make voltage and resistance checks;

d. Defective component in power sup-

replace defective component.

ply or vtvm circuit.

Check C31 and replace if defective,

a. Defective C31.

3. Function switch S4 is set to METER.

d. Check V14 or solid-state rectifier;

b. Defective V14 or solid-state recti-

Af oscillator adjusted to deliver

replace if defective.

fier CR1 or CR2.

several volts at 1,000 Hz, is con-

e. Check M1; replace if defective.

c. Defective meter M1.

nected to METER binding posts.

The oscilloscope, connected to

OSCILLOSCOPE binding posts,

shows 1,000 Hz output but indica-

tion is 0 or very low.

a. Check tubes and replace defective

a. Defective V2, V3, V4, V5, or V6.

4. Function switch S4 is set to NOISE.

tube.

AF-RF selector switch S2 is set to

b. Check switch contacts. Replace de-

AF (TS-723A/U) Af oscillator,

b. Defective contacts on S2, S4, or S6

fective switch if trouble is not cor-

if no reading is obtained.

adjusted for 0.8 volt and 1,000 Hz,

rected by cleaning contacts.

is c o n n e c t e d to AF INPUT

binding posts. Signal INPUT con-

NOTE

trol R4 is set to MAX. Meter

In the TS-723A/U, switch S6

range switch S6 is set to 100

must be replaced as an assembly

R.M.S. VOLTS. Meter M1 indi-

including R58, R88, and C25, In

cates significantly lower than 1

all other models, R58 and R88

volt or there is no meter indica-

and R92 through R98. Capacitor

tion.

C25 is not included on the S6

switch assembly,

c. SET LEVEL GAIN control R38

c. Refer to paragraph 7-16,

not properly adjusted.

d. NOISE GAIN control R5 not prop-

d. Refer to paragraph 7-16.

erly adjusted.

e. Defective component in preampli-

e. Make voltage and resistance checks.

fier or bridge amplifier circuits.

Defective contacts on S4.

Check contacts of S4; replace if nec-

5. Function switch S4 is set to SET

essary.

LEVEL. AF-RF selector switch

S2 is set to AF (A model only).

Af oscillator, adjusted for 0.8

volt and 1,000 Hz, is connected

to AF lNPUT binding posts.

Signal INPUT control R4 is set

to MAX. Meter range switch S6

is set to 10 R.M.S. VOLTS. Meter

M1 indicates significantly lower

than 1 volt, or there is no meter

indication.

79. Isolating Trouble Within Stage

technique to isolate the defective part.

a. Test the tube involved using either the rec-

After the trouble has been localized to a stage

with the troubleshooting table, use the following

ommended test set or the standard tube substitu-

7-9