Sect. IV Page 6
TROUBLE SHOOTING CHART
SYMPTOM AND
POSSIBLE CAUSE TEST PROCEDURE REMEDY
1. Instrument NOT operating, index
window NOT lighted.
a. Fuse open due to def-ctive . Replace fuse. If new fuse blows, .a
fuse or overload inpower sup- remove V5, and replace fuse.
Ply.
(1) Blowing of 2nd fuse indicates: I)
A. Short circuit inwiring as- A. Locate and clear short.
sociated with T1.
B. Short circuit in filament B. Locate and clear short.
wiring.
C. Defective transformer T1. C. Replace transformer.
(2) No opening of 2nd fuse with
V5 removed indicates:
A. Defective rectifier V5. A. Replace V5.
B. Internal short circuit in B. Locate and replace defective
V1. V2, V3, or V4. tube.
C. Short circuit ind-c wiring. C. Locate and clear short.
D. Defective C21ABC. D-c D. If defective, replace C21.
resistance from pin 8 of
V5 to ground normally is
approximately 8megohms,
disconnect line voltage be-
fore measuring,
b. Poor connection to line volt- . Check power cable, and connec-
age. tions at both ends of cable.
I. Instrument NOT operating; index
window lighted.
a. Power supply not operating . Check level of d-c voltage at pow-
properly . er supply output; should be t2 15V
+loyo. Use d-c voltmeter, such
as Model 410B; connect voltmeter
t terminal to terminal 3 or 4 on
capacitor C21, and voltmeter -
terminal to chassis.
If voltmeter indication not 215V . Replace defective component.
+lo%, checkrectifies tube V5, and
then other components of power
supply.
b. Defective tube in oscillator . Check forbad V1. V2. V3, or V4 . Replacedefective tube. See para-
circuit. by substituting tube of same type graph 4-3.
known to be good.
c. D-c potential applied to tube . Check d-c voltages on pins of all . If potential on any pin not correct
pins not of proper value. tube sockets; voltages should be value, check resistors in power-
within +lo% of values shown in supply network associated with
voltage and resistance diagram incorrect potential.
and schematic.
. If resistance measurements in-
d. Short circuit in fixed capac- . (1) To check capacitors C8A,
itor C7, variable capacitor C8B, C8C, C6 and C7: dicate short, before making fur-
C6, C8 or C14. A. Disconnect Model -hp- ther checks, visually examine C8.
i- 207A from line. If C8, is dirty, gently blow dust
B. Connect one ohmmeter from plates with air hose, and
terminal to C8B stator and then again make resistance meas -
other to C8 rotor. urements .
C. Ohmmeter should indicate
> 100 megohms. |
ACEC
