16. Voltage Measurements
17. Localizing Troubles
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
and resistance measurements are shown in fig-
that the switches and controls are set as indi-
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
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.
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-
3
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.
4
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
5
not indicate.
G R I D BIAS VOLTS meter Check meter M2 and replace if
defective.
M2 defective.
20
AGO 1428A
