HP 416A - Page 82

i
O'
.;::..
i
Instrument op er -
ating but meter
indi c ator action is
unstable or erratic
(cont'd),
416A004 =1 10/26/55 Seriat 79 an 'd above
Defective filter
(cont ' d) o
Trouble in one of
the delayed A VC
circu it s or one of
the multiar com -
parator circuits o
Incident Channel
Reflected Channel
7 0 c 0
Filter 2 ( cont
1
d)
Signal side of C9 to ground o
(Signal side is the back terminal on
the edge of the filter assembly which
is toward the rear of the instrument.)
CAUTION : Components of the two filters
are selected and tested at the factoryo
Under no circumstances should any
attempt be made to repa i r filters be -
yond locating and resoldering open
wiring and connections o
If either filter is found to be defec -
tive, a matched pair should be ordered ;
see Table of Replaceable Parts
0
8
0
To localize trouble in a delayed A VC or
multiar comparator circuit it is recom -
mended that the DC voltages for a tube
in a given circuit in the reflected
channel be compared with the DC volt-
ages for the tube performing the car -
responding function in the same cir-
cuit in the incident channel
0
For ex-
ample, measure the DC voltages at
tube VlO and compare them with the DC
voltages measured at VS : corresponding
voltages for the two tubes should be
approximately the same, and within ±5%
of those shown in the schematic. If
deviation is found, the trouble spot
probabl y is in that section of the circuit
where the deviation occurs, and components
in that section of the circuit should be
tested to find the defecti ve parL
Replace any de-
fective component
Delayed AVC
Multiar
C om parator
V5,V6A,V6B,V7A , V8B
VlO , VllA , VllB, Vl2A, Vl3B ,
V8A , V7B
VI.3A, V l2 B