Tektronix 2213 - Page 209

PRERE G UL ATO R
AND I NVERTER
T ROUBLESHOOT I NG
REMOVEPOWER FROM
ΤΗΕ
I NSTRUMENT
T ROUBLESHOOT
PREREGULATOR
FOR
S HORTED OR
OPEN
COMPONENTS
REPLACE
FUSE
REMOVE POWER
FROM ΤΗΕ
I NSTRUMENT
TROUBLESHOOT
TO
REMOVE S HORT .
CHECK C R931, CR932
C R933, CR934,VR938
C937,
Q940,
AN
D Q942
F OR SH OR TS .
(Q94 θ AND Q942
SH O UL D
BE REPLACED AS Α PA I R
I F
ONE
I S
SHORTED)
REV D EC 1981
CONNECT DMM TO
MEASURE ΤΗΕ
+45V
PREREGULATOR
O U T PU T AC R OSS VR 938
S H ORT P I NS 1 A
N D 2
O FU 931 TOG ET HER
L OWER A UTO
TRANSFORMEROUTPUT
TO ZERO V .
SHORT B ASE OF
0956 TO ΤΡ 934 .
RA I SE A UTO
TRANSFORMER S LOWLY
TO +85V RMS .
W ATCH
+45V LEVEL
T ROUBLESHOOT
I NVERTER
CONTROL
CI RCU I TRY
COMPONENTS
Q948, Q954, Q956
A ND Τ 942
CONNECT I NSTRUMENT
TO AC-POWER SOURCE
V I A AN AUTO
TRANSFORMER AND
AN ISOLATION
T RANSFORMER
(S EE NOTE 1) .
A PPL Y P
O WER TO ΤΗΕ
I NSTRUMENT AND
SLOWLY R A I SE ΤΗΕ
A UTO T RANSFORMER
OUTPUT V OLTAGE .
(DO NOT E XCEED
85 VRMS I NPUT)
ι