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1 8
Apply a load-resistance of I Mohm to the 2 re-
maining pins of the 4-pin plug. The voltage de-
veloped across this resistance should amount to a
value between 2 and 2.5 V. The brown wire
should be negative with respect to the orange one.
lncrease the input voltage to 3 mV. The output
should be equal to 5 V or exceed that value.
Change the polarity of the input voltage; the out-
put voltage should be equal to or exceed 5 V,
if possible, equal to the value, stated at the pre-
vious measurement.
Remove the voltage from the 3-pin plug and inter-
c o nne c t pin ' ( 2 )) and pi n s 53 ". Th e o utp ut s ho u l d
be equal to or smaller than 20 mV.
The noise across resistor R3 I 7 should be
mVrms.
Remove the interconnection. Now the noise mav
not exceed 50 mVrms.
Note: If one of the last two requirements is not met,
the input transistor TS30l (2N930) should be
replaced.
B.
GRID.CURRENT
COMPENSATION
R108 (Fig. l4),
Set the knobs of the basic oscilloscope to the
following positions:
"TRIGG. MODE"
: "AUT"
" T R I GG . S O U R C E " ' : " I N T "
"'ff ME/cm"
: "5 msec. /cm"
"X-DEFLECTION"
: "TIME BASE A"
-
At the unit, set "V / cm" (SK4) to "0.5 mY / cm"
an d (R 2; t o " C A L. " .
Adjust "SHIFT" (R3) so that the trace is in the
middle of the screen. Short circuit the input con-
nector.
Adjust "Ig. COMP" (R 108) so that the trace
does not ju-p
when button "CHECK ZERO"
(S K 2) i s dep ress ed.
R457
'+
R449
F
@
I np u t
C op o c i tors
Sq u ore W ov e
R es po n s e
Fig. 14. Lef t-hand view
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