Voltage Measurements

16. Voltage Measurements

17. Localizing Troubles

(figs. 11, 12, and 13)

a. General. In the troubleshooting chart (c

a. Measure the tube socket voltage with the

below), procedures are outlined for isolating

multimeter. Refer to the tube socket diagram

troubles to a particular component part. Voltage

(fig. 11) for voltages normally present. Be sure

and resistance measurements are shown in fig-

that the switches and controls are set as indi-

ures 1113. Depending on the nature of the op-

cated in the Notes column on figure 11.

erational symptoms, one or more of the localiz-

b. Measure the voltage at the test points on

ing procedures will be necessary.

b. Use of Chart. The troubleshooting chart is

the front, rear, and top of the chassis with the

designed to supplement operational checks that

multimeter. Refer to figures 11 and 12 for typi-

cal voltages. Be sure that the switches and con-

can be performed at an organizational level. If

trols are set as indicated in the Notes column on

previous operational checks have resulted in

reference to a particular item of the chart, go

figures 11 and 12.

c. Measure the voltage at the test points on

directly to the referenced item. If no operational

the resistor mounting board (fig. 13) with the

symptoms are known, begin with step 1 of the

multi meter. Be sure that the switches and con-

equipment performance checklist (TM 116625

trols are set as indicated in the Notes column

31612) and proceed until a symptom of trou-

on figure 13.

ble appears.

c. Troubleshooting Chart (fig. 26).

Symptom

Step

Probable trouble

Correction

PILOT lamp 11 does not light and Fuse F1 or F2 defective or

Check fuses F1 and F2. Replace as

burned out.

necessary. If replaced fuse burns

tube tester fails to operate.

out, check plate supply (terminals

3-14 of transformer T2) and ca-

pacitors C3 and C4 for short cir-

cuits.

Check lamp 11 and replace if neces-

PILOT lamp 11 defective

sary.

Check power cord and connector

Power cord defective

and replace if necessary.

Check meter M1 and replace if

PILOT lamp 11 lights but FILA- F I L A M E N T VOLTS meter

necessary.

MENT VOLTS meter M1 does

Ml defective.

not indicate.

Filament transformer T1

Check resistance of T1 (par. 18).

Replace 1 if necessary.

(fig. 3) defective.

FILAMENT RANGE switch Check switch S1. Replace switch S1

if necessary.

S1 defective.

Check primary windings of trans-

PILOT lamp 11 lights but PLATE Power transformer T2 pri-

mary winding open or short- former T2 (figs. 4 and 12, par.

meter M5, SCREEN VOLTS

18b). Repair defective wiring or

meter M6, GRID BIAS VOLTS

circuited.

replace transformer if necessary.

meter M2, and SIGNAL meter

M4 do not indicate.

W i t h FUNCTION switch S4 in

Plate supply tube V1

Replace V1.

TEST position and PLATE-

defective

SCREEN RANGE switch S3 in

any position but OFF, PLATE ,

PLATE meter M5 defective-----

Check meter M5 and replace if

meter M5 indicates zero plate

necessary.

voltage.

P L A T E - S C R E E N R A N G E Check switch S3 and replace if

necessary.

switch S3 defective.

Transformer T2 secondary

Replace T2.

winding 314 open.

GRID BIAS VOLTS meter M2 does Bias supply tube V2 defective.

Replace V2

not indicate.

G R I D BIAS VOLTS meter Check meter M2 and replace if

defective.

M2 defective.

AGO 1428A