EIRCIITT DESCRIPNON v
BLOCK DIAGBAM ANALYSXS
Refer to Fig. 2, whieh is a bloek diagramof
the oseilloseope.
The vertieal ehannel eireuits inelude the
vertieal attenuator and vertieal amplifier.
The VERT INPUT signal is applied throughthe
AC-DC switeh, whieh seleets eapaeitive or
direet eoupling,
Md through the V ATT (verti-
eal attenuator) to the vertieal amplifier. The
vertieal amplifier is a highly stable, direet-
eoupled
differential amplifier with a gain of
approximately
61 dB, giving a maximum
sensi-
tivity of approximately 10 mV per division.
The vertieal attenuator andvertieal gaineon-
trol reduee the signal when lessoutput is re-
quired. Theoutput of the vertieal amplifier is
appliedto the vertieal defleetion platesof the
CRTwhen
the NOR-DIR
switehisset to NOR.
When
the NOR-DIR switeh is set to DIR, the
output of the vertieal amplifier is diseonneet-
ed and a signal from the V DIR and GND ter-
minals is applied direetly to the vertieal de-
fleetion plates.
The horizontal ehannel eireuits inelude a
sweep generator for a time base and a hori-
zontal amplifier. The reeurrent type sweep
generator is a free runningsawtooth oseillator
whiehproduees
the sweepwaveform. Its fre-
queney range is seleeted by the SWEEP
RANGEswiteh, and fine frequeneyeontrol is
provided by the SWEEPVAR eontrol The
INT-EXT switehseleets
the synesignal
for the
sweep
generatorfrom the vertieal ehannel,
or
theEXTSYNC
input.
The sawtooth wave is amplified by the
horizontal amplifier and applied to the hori-
zontal defleetion plates of the CRT. The
horizontalamplifier is a stable,
direet eoupled
differential amplifier with a gain of approxi-
mately 35 dB. The horizontal amplifier may
also be used to amplify an external signal
appliedat the HOR INPUTjaek. In this mode,
the EXT GAIN eontrol allows the gain.
to be
varied
by about10dB.
The power supply provides operating volt-
ages for all eireuits. The regulated +15
V'
-15V, and-6 V sourees
are used
in the vertieal
preamplifier and sweep generator eireuits.
thg +170V souree
is used
in the vertieal and
horizontal final amplifier stages. The high
voltage souree provides about -1400 volts
aeeeleration
voltage for the CRT beam. The
Z-axis input is applied to the eontrol grid'
where it may be usedas intensity modulation
of the CRTbeam.
YEBIICAL CHANNEL CIRCI'NS
Refer to Fig. 3 for a simplified diagram
of
the vertieal ehannel
eireuits and to the sehe-
matie diagram in the rear of the manual for
full eireuit detaills.
Input Cireuit ;
The vertieal input signal is first routed to
the AC-DC eouplingswiteh, 53. Switeh S3
seleetsor bypasseseapaeitor Cl. In the AC
position, Cl is eonneeted
in series with the
input. In the DC eoupling
position,eapaeitor
Cl is bypassed
and the input signal is eoupled
direetly to the attenuatorswiteh.
Vertieal Attenuator
Thebasiesensitivityof the vertieal ehannel
is 10 mV/division. The vertieal attenuator
expands the input range by offering three
sensitivity stepsof 10 mV/div, 0.1V/div' and
1 V/div. This is aehieved
by voltage divider
networks, seleeted by S1a and Slb' whieh
attenuate the input to the vertieal preampli-
fier by Xl (direet), X10, or X100. Trimmer
eapaeitors
TC101
andTC102
provide
frequen-
ey eompensation
for the XL()and X100steps'
to mateh
the Xl step. A eonstant
inputimpe-
danee
of 1 Megohm
is maintained
in all steps.
A fourth step of switeh S1 opensthe VERT
INPUT path and grounds the input of the
vertieal preamplifier. This establishes a v
eonvenient
0-volt referenee.
