ScienTECH Scientech 801C User manual

30 MHz Oscilloscope
Scientech 801C
Learning Material
Ver. 1.1
An ISO 9001:2008 company
Scientech Technologies Pvt. Ltd.
94, Electronic Complex, Pardesipura, Indore - 452 010 India,
+ 91-731 4211100, : [e-mail] , : www.ScientechWolrd.com

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Scientech Technologies Pvt. Ltd. 3

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RoHS Complian
ce
Scientech Products are RoHS Complied.
RoHS Directive concerns with the restrictive use of Hazardous substances (Pb, Cd, Cr,
Hg, Br compounds) in electric and electronic equipments.
Scientech products are “Lead Free” and “Environment Friendly”.
It is mandatory that service engineers use lead free solder wire and use the soldering irons
upto (25 W) that reach a temperature of 450°C at the tip as the melting temperature of the
unleaded solder is higher than the leaded solder.
30MHz Oscilloscope
Scientech 801C
Table of Contents
1. Safety Instructions 5
2. Introduction 6
3. Features 7
4. Technical Specifications 8
5. Panel Diagram 9
6. Panel Controls 10
7. Back Panel 11
8. Operating Instructions 12
9. Warranty 19
10. List of Accessories 19

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Safety Instructions
Read the following safety instructions carefully before operating the instrument. To
avoid any personal injury or damage to the instrument or any product connected to it.
Do not operate the instrument if you suspect any damage within.
The instrument should be serviced by qualified personnel only.
For your safety:
Use proper Mains cord : Use only the mains cord designed for this instrument.
Ensure that the mains cord is suitable for your
country.
Ground the Instrument : This instrument is grounded through the protective
earth conductor of the mains cord. To avoid electric
shock the grounding conductor must be connected to
the earth ground. Before making connections to the
input terminals, ensure that the instrument is properly
grounded.
Observe Terminal Ratings : To avoid fire or shock hazards, observe all ratings and
marks on the instrument.
Use only the proper Fuse : Use the fuse type and rating specified for this
instrument.
Use in proper Atmosphere : Please refer to operating conditions given in the
manual.
1. Do not operate in wet / damp conditions.
2. Do not operate in an explosive atmosphere.
3. Keep the product dust free, clean and dry.

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Introduction
EasyScope - Scientech 801C is a New Trend Oscilloscope with feel of Digital
Touch. The Digital Readout Backlit LCD displays Volts/Div and Time/Div settings.
Rugged yet light weight 801C has sharp and bright trace. The Vertical Bandwidth is
more than adequate for all your needs and you can easily view signals upto 40 MHz.
Built-in component tester, which makes it an indispensable instrument, this allows
both passive and active components to be tested, while still in-circuit.

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Features
Digital Readout with Backlit LCD
30 MHz Bandwidth
x10 Magnification
20 ns max sweep speed
Stable Triggering upto 40MHz
Alternate Triggering
Sharp Trace CRT & Auto focus
Gold Plated BNC Connectors
Built - in – Component Tester

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Technical Specifications
Operating Modes:
Channel 1, Channel 2, Channel 1 & 2
alternate or chopped (approximately
350KHz), X - Y (Ratio 1:1 Input via
CH2), Add/ Sub CH1± CH2, Invert
CH2.
Vertical deflection (Y):
(Identical channels)
Bandwidth: DC - 30MHz (-3dB)
Rise Time: 12ns (approximately).
Deflection coefficients:
Micro-controller based 12 calibrated steps
5 mV/Div–20 V/Div (1-2-5 sequence).
Electronic Control Display on 32 character
backlit Alphanumeric LCD.
Accuracy: ± 3%
Input Impedance: 1M | | 30pF
(approximately)
Input: Gold plated BNC
Input coupling: DC-AC-GND
Maximum Input voltage: 400V (DC
+ Peak AC).
Time Base:
Time coefficients: Micro-controller based
18 calibrated steps, 0.5s/Div - 0.2 s/Div
(1-2-5 sequence) with magnifier x10 to 50
ns/Div, with variable control to 20ns/Div.
Electronic control display on 32 character
backlit Alphanumeric LCD.
Accuracy: ± 3% (in cal position)
Trigger System:
Modes: Auto / Level
Source: CH1, CH2, Alt CH1/CH2,
External.
Slope: Positive or Negative
Coupling: AC
Sensitivity: Internal 5mm, External 0.8V
(Approximately).
Trigger Bandwidth: 40MHz.
Horizontal Deflection (X):
Bandwidth: DC - 2.5MHz (-3 dB).
X-Y mode: Phase Shift < 3° at 60KHz.
Deflection coefficients: Micro-controller
based 12 calibrated steps 5 mV/Div-20
V/Div (1-2-5 sequence). Electronic
Control Display on 32 character backlit
Alphanumeric LCD.
Input Impedance: 1M ||30pF
(approximately)
Input: Gold plated BNC
Built-in Single Touch Component
Tester
Test Voltage: Max 8.6Vrms Open
Test Current: Max 8mArms Shorted
Test Frequency: 50 Hz, Test circuit
grounded to chassis
Continuity Tester: Beeper sounds
<75 approx.
General Information:
Cathode Ray Tube: 140mm Rectangular
tube with internal graticule. P31 Phosphor
Accelerating potential: 2KV
(approximately)
Display: 8 x 10cm
Trace Rotation: Adjustable on front panel
Calibrator: Square Wave Generator
1KHz (approximately), 0.2Vpp ± 1% for
probe compensation.
Stabilized Power Supply: All operating
voltages including the EHT
Mains Voltage: 230V ±15%, 50Hz. 60Hz
on request
Power Consumption: 45VA
(approximately)
Weight (approx): 7.5Kg. (approximately)
Dimensions (mm): W325 x D370 x H155
Operating Temperature: 0-40C°; 90% RH
(Subject to change)

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Panel Diagram

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Panel Controls
(1) Power ‘On/Off’ : Rocker switch for supplying power to instrument.
(2) X10 : Switch when pushed gives 10 times magnification
of the X signal.
(3) XY : Switch when pressed cuts off the time base &
allows access to the external horizontal signal to
be fed through CH2 (used for X - Y display).
(4) CH1/ 2 : Switch selects channel & trigger source (released
Trig 1/ 2 CH1 & pressed CH2).
(5) Mono/ Dual : Switch selects Mono or Dual trace operation.
(6) Alt/ Chop/ Add : Switch selects alternate or chopped in Dual mode.
If Mono is selected then this switch enables
addition or subtraction of channel i.e.CH1 ± CH2.
(7) Ext : Switch when pressed allows external triggering
signal to be fed from the socket marked Trigger
Input (24).
(8) Alt : Selects alternate trigger mode from CH1 & CH2.
In this mode both the signals are synchronized.
(9) Slope (+/-) : Switch selects the slope of triggering, whether
positive going or negative going.
(10) Auto/Level : Switch selects Auto/Level position. Auto is used
to get trace when no signal is fed at the input. In
Level position the trigger level can be varied from
the positive peak to negative peak with Level
Control.
(11) Level : Controls the trigger level from peak to peak
amplitude of signal.
(12) Component : Switch when pressed starts CT operation.
Tester
(13) X Shift : Controls horizontal position of the trace.
(14) TB Var : Controls the time speed in between two steps of
Time/Div switch. For calibration put this pot fully
anticlockwise at Cal position.
(15) Intensity : Controls the brightness of the trace.
(16) TR : Trace Rotation controls the alignment of the trace
with graticule (screw driver adjustment).
(17) Focus : Controls the sharpness of the trace.

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(18) Cal Out : Socket provided for square wave output 200mV
used for probe compensation and checking
vertical sensitivity, etc.
(19) Volts/Div. : Switch selects Volt/Div. step for CH1 & CH2
(20) DC/AC/GND : Input coupling switch for each channel. In AC the
signal is coupled through 0.1MFD capacitor.
(21) CH1 (Y) & : BNC connectors serve as input connection for
CH2 (X) CH1 & CH2 Channel 2 input connector also
serves as horizontal external Input.
(22) Time /Div. : Switch selects Time/Div. steps.
(23) Component Tester Input: To test any components in the CT mode, put one
test prod in this socket and connect the other test
prod in ground socket.
(24) Trigger Input : Socket provided to feed external trigger signal in
External Trigger mode.
(25) Invert CH2 : Switch when pressed invert polarity of CH2.
(26) Digital Readout : LCD window for displaying Digital Readout for
Volt/Div. & Time/Div. settings.
(27) Y Shift 1 & 2 : Controls provided for vertical deflection of trace
for each channel.
Back Panel Controls
Fuse: 350mA fuse is provided at the back panel.

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Operating Instructions
General Information:
The 30MHz Dual Trace Scientech 801C is a compact, low line and just trouble free
new generation Oscilloscope. It is technically advanced, as particularly illustrated by
the increased use of microcontroller circuits. The logical arrangement of the controls &
connectors makes it easy to become familiar with the operation of the instruments.
However, even, experienced users of Oscilloscopes should read the following
instructions thoroughly before using the instrument.
Operating Conditions:
Ambient temperature range for operation: 0C - 40C; 90% RH
Ambient temperature range for storage transportation: - 20°C to + 70°C.
The instrument should be placed in a clean and dry room and should be operated in
normal position; however, the convection cooling must not be impaired.
First Time Operation & Presetting:
At the time of delivery, the instrument is set at 230VAC mains voltage. To obtain a
display:
All push buttons should be in the released position.
Instrument is turned ‘On’ by pressing "Power" ON button. An LCD indicates that
the instrument is ‘On’. It is recommended to switch on the instrument for about
30 minutes prior to commencement of any calibration check.
If no trace is visible after a warm-up of one minute:
a. Check "Intensity". It is possible that this control needs to be increased,
rotate knob clockwise.
b. Bring X&Y “Shift” controls in the centre. Check Auto/Level controls bring
it in Auto position.
If only a dot appears [Caution, the CRT phosphor could be damaged under this
condition probably] the push button for XY is pressed. If this is so, it should be
released.
Now, the trace should appear and the "Intensity" control should be adjusted for
average brightness, while optimum sharpness is obtained by adjusting the "Focus"
control.
At the same time both input coupling switch "DC-AC-GND" should be in the
"GND" position. Thus, the inputs of the Y-amplifiers are grounded preventing the
introduction of unwanted signals.
Check Time/Div. & Volts/Div. function by using rotary knobs.

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Type of Signal Voltage:
All signals whose frequency spectrum is below 30MHz can be displayed on the
Scientech 801C.
Simple electrical processes such as sinusoidal RF and AF signals or 50Hz ripple
voltages are easily displayed by the instrument.
However to display square or pulse shaped signals one has to remember that their
harmonic content must also be transmitted along with the fundamental. Hence the
bandwidth of the vertical amplifier must be set considerably higher than the
repetition of logic and pulse signals, particularly, if the duty cycle permanently
changes during the operation. Otherwise, the display will move up and down
without any change.
Display of composite signals which do not contain any suitable level components
for triggering cause greater problems. To obtain a well triggered display in such
cases, it is necessary to use the time base 'Var' control.
To be used as an AC or DC voltage amplifier, each channel is provided with an
'AC-DC' switch. Under normal conditions AC mode is used. Use of DC mode is
recommended only when acquisition of the DC voltage content signal is
absolutely necessary. However, when investigating very low frequency pulses,
disturbing ramp offset may occur with AC coupling. In this case DC coupling
must be used DC voltages are always measured in the 'DC' position. DC operation
is to be recommended even for the representation of logic and pulse, particularly
under conditions when the duty cycle changes permanently during the operation,
else, the display will move up and down with change.

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Magnitude of Signal Voltage:
Generally alternating voltage data normally refers to effective values (rms = root mean
square value). But, for signal magnitude and voltage in Oscilloscope tests the volt peak-
to-peak (Vpp) value (which is the value of real potential difference between the most
positive and most negative points of a signal waveform) is taken.
To convert a value of sinusoidal wave displayed on the Oscilloscope screen to its
effective value, the resulting voltage peak-to-peak value has to be divided by 2.83.
Conversely Vpp is 2.83 times Veff (Vrms) and is equivalent to the sinusoidal voltage.
The relations of the different voltages magnitude is given in the figure 1.
Figure 1
The minimum required voltage on the Y input for a display of 1cm amplitude is
2mVpp. However, smaller signals can be displayed. The deflection coefficients on the
input attenuators are indicated by Vpp/cm or mVpp/cm. The magnitude of the applied
voltage is ascertained by multiplying the selected deflection coefficient with the display
amplitude in cm. If an attenuator probe x10 is used, a further multiplication by 10 is
required with direct connection to the Y input, signals upto 160Vpp can be displayed. If
the applied signal is superimposed on a direct voltage, the total value (DC Peak value
of the alternating voltage) of the signal on the Y input must not exceed 400V.
Time Values of Signal Voltage:
As a rule all signals displayed are repeating process having a recurring frequency or
repetition rate which can be designated as "periods per second". For this, the units are
indicated on the "Time Base" switch s/cm, ms/cm and s/cm. accordingly, the
"Time Base" dial is subdivided into two sectors. The duration of a signal period or a
portion of the waveform is obtained by multiplying the relevant time fine control
marked "Var" must be in its calibrated position for accurate measurement (arrow
horizontal and pointing to the left).

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If the time is relatively short as compared with the complete signal period, an expanded
time scale (x10) should be applied. The ascertained time value is to be divided by 10 in
this case. When investigating the pulse behaviour of a signal voltage, the critical feature
is the rise time of the voltage step. To ensure that transients, ramp offsets, and
bandwidth limits do not unduly influence the measuring accuracy, the rise time is
generally measured between 10% and 90% of the vertical pulse height.
Figure 2

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Connection of Test Signal:
The signal displayed should be fed to the Y input of the Oscilloscope through a
shielded test cable or by an x10 attenuator probe. The use of these cables with high
impedance circuits is only recommended for relatively low frequencies (upto
approximately 50KHz). For higher frequencies, and when the signal source is of low
impedance, a cable of matched characteristic impedance (usually 50 ) is recommended
when investigating square or pulse waveforms with fast rise times, transient
phenomenon on both the edge and top of the signal may become visible, if the correct
termination is not used. It must be remembered that the 50 through termination will
dissipate a maximum of 2 watts. If an x10 attenuator probe is used, no termination is
necessary. In this case, the connecting cable is matched directly to the high-internal
impedance sources are only slightly loaded. Therefore, it is advisable to use x10 probes
when the voltage loss due to the attenuation of the probe is compensated by a higher
sensitivity setting on the Oscilloscope Scientech 801C. Using of probes also provides
series protection for the input of the Oscilloscope amplifier.
Note: That all attenuator probes must be compensated in conjunction with the
Oscilloscope.
It is important to remember that for display of small signal voltage the position of the
ground point on the test circuit should always be located as close as possible to the
measuring point otherwise it will result in serious signal deformation from any
invalidated currents through ground leads or chassis parts. Also ground leads of the
attenuator probes should be ideally being as short and thick as possible.
If after connecting the test signal, the trace disappears suddenly, the signal amplitude
may well be too great, i.e. the amplifier is over scaled. In such case, the attenuator
switch should be turned anticlockwise, until the vertical deflection is only 3-7cm. For
signal amplitudes greater than 160Vpp a x10 probe should always be used. If after
connecting the signal the intensity of the trace is low, it is possible that the period of the
test signal is substantially slower that the value set of the "Time Base" switch. This
control should then be turned anticlockwise to a corresponding slower time coefficient.


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Probe Compensation:
For the undistorted display of signals, the x10 attenuator probe must be compensated to
match the input impedance of the vertical amplifier. This is done by connecting probe
tip to the mini-socket on the instrument marked with a square wave, and adjusting the
trimmer tool supplied with the probe. In Scientech 801C,the probe compensation is
easily achieved due to the built in Square Wave Generator with a repetition frequency
of approximately 1KHz and an output voltage of 0.2Vpp. The correct display is shown
in figure given below.
The "Time Base" switch should be in the 0.2ms/cm position. The signal has an
amplitude of 0.2Vpp ±1 %. If the attenuator switch is set to 50mV/cm, the display will
have a height of 4cms (1:1 probe). Since an attenuator probe is constantly subjected to
considerable stresses, the compensation should be frequently checked.
Figure 3
Operating Modes:
The required operating modes are selected with push buttons in the vertical amplifier
section. For selecting either channel, CH1/CH2 is pressed or released, while selecting
either channel; it also selects triggering of respective channels. For selecting both the
channels, Dual is pressed, the alternate or chop can be selected by pressing Alt/Chop
switch. For addition of channel, release Mono/Dual switch & press Alt/Chop push
button, which will display addition of CH1 & CH2. Similarly, subtraction of CH1-
CH2 can be achieved by pressing Invert CH2 & Add mode.
For X - Y operation the "XY" button must be pressed. The X signal is connected via the
input of channel 2. The sensitivity of the horizontal amplifier during X - Y operation is
selected by the CH2 attenuator switch. The sensitivity and input impedance for both the
X & Y axes are equal. Note that the frequency limit of the X axis is approximately
2.5MHz (-3dB). Therefore, an increase in phase difference is noticeable at higher
frequencies. The phase shift is 3 degrees approximately at 60KHz.

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Trigger and Time Base:
Time Base operation is important for obtaining a satisfactory stable display. If the
"Auto" push button is not pressed the sweep generator will be triggered automatically.
The time axis (baseline) is then also visible without applying a signal voltage. In this
position practically all uncomplicated, periodically recurring signals above 30Hz
repetition frequency can be displayed in a stable locked-in position. Operation of the
time base is then restricted mainly to adjusting the time setting.
To obtain a stable display at all frequencies the time base must be triggered
synchronously with the applied signal. Triggering can be initiated by this signal itself or
by a different external fed-in voltage, which must also be in synchronism. For this
purpose, press the Ext button. The trigger signal (at least 0.6Vpp) is applied to the
socket marked "Trigger Input". On single channel operation a trigger signal may also be
applied to the input of channel 2 (in this case trigger selector button "Trig 1/2" must be
pressed). This method is recommended if the amplitude of the trigger signal does not
fall in the range 0.6 - 6Vpp, or if it is of unknown value. Using this method the signal
can be adapted to the trigger input of the time base within a range of 2mVpp to
approximately 160Vpp by means of the CH2 attenuator switch. Initially the unknown
external trigger signal should be displayed and then adjusted to peak-to-peak amplitude
of 3-6cm. The trigger signal can be taken either from CH1 or CH2. Selection is made
by means of the button marked "Trig 1/2" on the front panel. If possible, it is always
better to trigger with the less complicated signal. To select the trigger edge, use the"+/-"
button. When it is not pressed, all displays start with a positive going rise.
If the pulse duty factor of a square signal changes drastically, and a part of this square
wave deforms to a needle pulse, the operation of the "Level" control may become
necessary, after pressing "Auto/Level" switch. With composite signals the trigger
facility is dependent on the occurrence of certain periodically recurring levels. The
"Level" adjustment of these signals will require care.
If no triggering point can be found on complex signals even after repeated and careful
adjustment of the "Level" control, it may be possible to obtain one by adjusting the
"Var" control.
All coefficient settings on the "Time Base" switch are calibrated when the "Var"
control is set at the "Cal" position. With "Var" control in the clockwise position the
sweep rate is made faster by a factor of 2.5. This factor in not precisely calibrated. With
the x10 expansion of the sweep a maximum sweep speed of approximately 20ns/cm is
obtained. The choice of the optimum time coefficient depends on the repetition rate of
the signal being measured.