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The standard used in the instrument:
EN61010-1(1993) Safety requirements for electrical equipment for
measurement, control, and laboratory use
EN-IEC61326-1(1997) EMC requirements for electrical equipment for
measurement and laboratory
The enterprise has passed ISO9001 International Quality System Attestation,
The products has been designed and manufactured according to ISO9001.
Ⅰ
1
Matters needing attention
Please read the following matters needing attention to avoid body damage and prolong the usage
life. The instrument can only be used in specified conditions and only qualified technicians can
repair the machine.
Fire and body damage protection
·Use proper power lines. Only power lines those are specified for the instrument and in the
specified country can be used.
·The instrument should be grounded. The instrument is grounded through the grounding lead of
power lines. The grounding conductor should be grounded to the earth. The grounding terminal on
front panel is connected to the instrument to avoid electric shock and body damage. Be sure that the
instrument is safely grounded before it is connected with any plugs.
·Don’t operate the instrument without covers. Please don’t operate the instrument if its covers
are moved away.
·Use proper fuses. Only the fuses those are specified for the instrument can be used.
·Don’t use the instrument if it is doubt that something is wrong with it. If it is doubt that there
is anything wrong with the instrument, let those specified technicians check the instrument.
·If the oscilloscope is used to measure the voltage in the electric net, some additional measures
Ⅱ
2
should be adapted beforehand. If the probe were connected to the electric net directly, the probe or
the inner circuit of the oscilloscope would be damaged.
Prolong the working life
Storage & usage
·Don’t use the instrument in very cold or hot condition. The working temperature is 0℃～40℃.
Don’t move the instrument from very cold places to very hot places. Or the hydrosphere would
condense inside the instrument and on the screen.
·Don’t put the instrument in very wet places or the places of much dust. The best relative humidity
for usage is 35%—90%.
·Don’t put the instrument in vibrating places or the places of strong magnetic field.
Operation
·The ventilating holes on the instrument cannot be plugged or inserted with metal or leads.
·Don’t put the instrument upside down or pull the instrument with the probes or connecting lines.
·Don’t put electric irons on the surface or frame of the instrument.
Clearing Use soft cloths with neutro-detergent to clean the rust or dust. And the detergent of high
volatility such as benzene cannot be used.
Calibration Period In order to maintain this equipment in stable and efficient operating condition,
calibrate the equipment after every 1,000 hours operating time, or every 1 year, whichever is
shorter.
Ⅲ
3
The following markers maybe appear in this manual or the product:
No.
Symbol
1
Explanation
No.
Symbol
Explanation
DC
7
AC
8
3
GND
9
4
Protective grounding
10
5
Connected to Frame
11
Push switch controlling in
6
ON (power)
12
Push switch controlling out
2
～
OFF (power)
＋、－
Positive、Negative
Electric shock warning
!
Ⅳ
4
Warning
Contents
Brief Introduction······························································ 1
1. General·····································································
2
2. Technical Specification ······················································
3
3. Description of operating controls ············································· 10
4. Operating Methods··························································
25
Brief Introduction
Thank you for purchasing the oscilloscope.
Please read the manual carefull y prior to use and keep it well then.
The instrument is produced strictl y according to the standards for qualit y and all
the elements are selected carefull y.
After-sales Service: If there is anything wrong with the instrument, please contact
our sales center as soon as possible.
Caution: Onl y the oscilloscope is in the specified condition, can it be in good
working state.
During carriage, the trace of the instrument might slant sligh tly. If so, please adjust
the trace knob on the front panel to make the trace parallel with the horizontal
scale.
1
1. General
1.1 Features
the oscilloscope is small and of light -weighted. It has the function of B dela y
sweep and has the following features:
(1)Wide frequency range: DC -100MHz -3dB.
(2)High sensitivit y: 1mV/DIV (×5 MAG).
(3)In ALT (A and B alternatel y sweeps) mode, four traces are displayed.
(4)Fast sweep rate to 5n s/DIV by magnifying 10.
(5)The function of B TR IG ’D can decrease the delay shrinking.
(6)Hold-off function makes it easier to catch the complex triggering signals.
1.2 Configuration
The standard accessories supplied are as follows:
(1) Oscilloscope······················································ 1
(2) Probe····························································· 2
(3) Power cord ······················································· 1
(4) Instruction manual ····
··········································· 1
(5) Spare fuses ······················································· 2
2
2. Technical Specification
Item
Specification
2.1 Vertical Axis
CH1 and CH2
sensitivit y
Accuracy
5mV/DIV to 5V/DIV 1 -2-5 step, 10 calibrated steps (1mV/DIV t o
1V/DIV at ×5 MAG) ①
×1： ±3%， ×5： ±5%
(Vertical knob i s set to CAL position)
Variable vert Ical sensitivit y
Be less than 1/ 1 to 1/3(less than 1/2.5 ti mes) ①
Frequency band
width×5MAG
DC:DC to 100MHz
AC:10Hz to 100MHz
-3dB ③
AC:10Hz to 15MHz
20MHz
Bandwidth
DC:DC to 20MHz
AC:10Hz to 100MHz
Rise ti me
Approxi matel y 3.5ns ( OVER SHOT< 5%) ④
Approxi matel y 23ns by ×5MAG
Approxi matel y 17.5ns with the bandwidt h of 20MHz
3
-3dB
③
DC:DC to 25MHz
-3dB
③
CROSS TALK
30:1 AT 100KHZ
⑧
Square Wave Charact eristics Ove rshoot less than 5% , 10mV/ div range ⑤
Item
Input i mpedance
Maxi mum input
voltage
Input coupling
system
Operating systems
Invert
Overshoot
Specification
1MΩ ±2%, 25 pF±3pF ②
400V (DC+AC peak) 1kHz
AC-GND-DC
CH1、 CH2、 ADD、 DUAL（ CHOP、 ALT） ⑦
Onl y CH2 si gnal is inverted
Max 8%
2.2 Triggering
Trigger mode
⑥
AUTO, NORM, TV-V,TV-H
Trigger si gnal source INT, CH2, LINE, EXT
4
Polarity
Coupling system
＋, －
AC coupling
r
INT
EXT
Frequency
Sensitivity
TV
Synchronization
1.5 div
30Hz to 110MHz
EXT
0.5 p-p
TV- V 2 0 H z – 3 0 k H z , 1 . 0 d i v ( i n t e r n a l ) , 0 . 5 p - p ( e xt e r n a l ) ,
TV- H 3 kH z – 1 0 0 kH z , 1 . 0 d i v( i n t e r n a l ) , 0 . 5 p - p ( e xt e r n a l )
EXTERNAL TR IGGER :Max imu m inpu t Voltag e 300V (DC + AC peak),
2.3 EXT trigger input
Input Impedance
About 1MΩ 25pF
Max Input Voltage
400V(DC+ACpeak) 1kHz
2.4 Z-axis
Input Impedance
About 40kΩ
Max Input Voltage
30V(DC+ACpeak)
5
III
II
Bandwidth
DC ～ 2MHz
Input si gnal
±5V (Negati ve i ntensity)
Item
Specification
2.5 Time axis
Sweep mode
A, B, B TRIG’D, X -Y, ALT
Sweep ti me
A: 0.05μ s to 0.2s/ DIV ±5%, in 21 calibrat ed steps(1 -2-5 seq)
B: 0.05μ s to 10μ s/ DIV ±5%, in 8 calibr ated steps(1 -2-5 seq)
⑨
Sweep expansion
×10 MAG: ±8% (0.1, 0.05μ s/DIV: Non-Cal)
Sweep Rate Varb
Less than 1/2.5
Delay System
Delay Time
Hold-off
Delay Time Start
point
Continuous delay or Triggering delay
0.2μ s ～ 2s
Continuous change for 2 times
20ns to 0.5s/div,
⑩
6
End Point
10div +1 div, delay jitter within 1/10,000 of full scale sweep time
DELAYED TIME BETWEEN CHANNELS WITHIN 1NS BETWEEN
CH1 and CH2
⑩
Delay Jitter within 1/10,000 of full scale sweep time
I
2.6 X-Y operation
Operating mode
Sensitivit y
X-axis band wi dth
Phase difference
CH1 X -axis and CH2 Y-axis When in X -Y operation mode
As vertical axis
DC ～ 2MHz
≤ 3 0 (DC ～ 100kHz)
5mV/div to 5V/div, CH1 AND ch2, Accuracy ± 3%, calibrated
Sensitivit y
Frequency Response
IV
position , ±6% using X10mag
DC to 2MHz (-3dB), CH2(Y)
7
V
OUTPUT
O u t p u t Vo l t a ge Ap p r o x. 1 0 0 mV / d i v o p e n c i r c u i t , A p p r o x. 5 0 mV / d i v i n t o
50Ω, Freq. Response 20 Hz to 100 MHz, -3 db Output Impedance
a p p r o x. 5 0 Ω ,
VI
2.7 CAL voltage
Frequency
About 1 kHz
Wavefor m
Square wave
Output level
0.5V (±3%)
Dut y
≥ 48: 52 ( min)
Item
Specification
2.8 CRT
Type
6 inch square internal scale
8
Acceleration voltage
Effecti ve screen
About 12kV
12kV
8div (vertical direction)×10div (horizontal direction)
12kV
2.9 Power supply
Range
198V ～ 242V
99V ～121 V
Voltage
Fuse
1A/250V
2A/250V
Frequency
50Hz ～ 60Hz
Power consumption
55W
Item
Specification
2.10 Environmental conditions
Operating temperature
0℃ to 40 ℃
9
Voltage
220V
110V
Operating humidity
35% to 85%
Guaranteed operating temperature
10℃ to 35℃
Guaranteed operating humidit y
45% to 80%
Guaranteed maintained temperature
-20℃ to 70℃
35% to 85% (Less than 70% at temperature
exceeding 50℃ )
Guaranteed maintained humi dit y
2.11 Mechanical specifications
Physical dimensions
Height
Width
Length
135 (H)
322 (W)
368 (D)
Weight
Approximatel y 7.5kg
3. Description of operating controls
3.1 Position Figure of Controllers
1
2
19
6
3
5
4
20
7
33
27
28
25
35
POWER
INTENSITY
10
FOCUS
TRACE SCALE ILLUM
ROTATION
POSITION
CAL
A X-Y
.5V
X-Y
DLY POS
B
ALT
24
34
B TRIG’D
100
90
A/B SEP.
BW LIMIT
+
-
B
POSITION
POSITION
ALT
TIME/DIV
VARIABLE
PULL×10MAG
.2 .1 50
SLOPE
20
39
A
23
Fig.3-1
40
Front Panel
38
41
Z-AXIS INPUT
11
CAUTION
THE POWER CORD PROTECTIVE GROUNDING
CONDUCTOR MUST BE CONNECTED TO GROUND.
DISCONNECT INPUT POWER BEFORE
REPLACING FUSE.
DO NOT REMOVE COVERS. REFER SERVICING
Fig.3-2
Rear Panel
3.2 Functions of Controllers
3.2.1 Front Panel
Fuse, AC input
Insert the power cable into the AC Input receptacle (40), and use the
corresponding fuse.
12
(1) Power switch ON/OFF
Verify line voltage; set power switch to the OFF position and insert the power
cable into the receptacle A C. Press the power push -button switch to turn the
power on. If the switch is released, the power is turned off.
(2) Power Indicator
This indicator lights when power is turned ON.
(3) Focus knob
Adjust the knob to make the sweep line clearest with the pr oper intensit y.
(4) Intensity Knob
Adjust the brightness of the scale on the screen. Turn it clockwise to increase
the brightness for operating in the dark condition or for photos taking.
(5) Trace rotation
This knob is used to correct the horizontal trace when it becomes slanted with
respect to the horizontal scale, due to the effect of magnetic forces.
(6) Scale Illum knob
It is used to adjust scale brightness of the dots or sweep traces.
(7) 0.5V Terminal for Calibrator
13
Output the square wave of 0.5V p-p 1kHz to calibrate the probes.
(8) Grounding Terminal
It is a grounding terminal.
3.2.2 Vertical axis section
(9) CH 1 Input Terminal
This is a BNC connector used for vertical input. The X-axis signal applied to
the terminal in the X-Y mode can be input.
(10) CH 2 Input Terminal
This is a BNC connector used for vertical input. The Y-axis signal applied to
the terminal in the X-Y mode can be input.
(11) (12) AC-GND-DC switch
Selects the coupling method to the vertical amplifier.
AC: The vertical input is connected through a capacitor. The DC component of
the input signal is blocked, and the AC component onl y is displayed.
GND: Input of vertical amplifier is grounded.
DC: Directl y coupled. Input signal, including DC component, is displayed on
the CRT.
14
(13) (14) VOLTS/DIV selector switch
This is a step attenuator switch, which varies the vertical deflection sensitivit y.
Set to the position, which displays the input signal at the most convenient
height on the CRT.
If a 10:1 probe is used, calculate as 10 -times the height
(15) (16) Var Knob
The fine adjustment is used for varying the vertical axis deflection sensitivit y
continuousl y. If this knob is turned completel y counter clockwise the vertical,
sensitivit y is reduced to less than 1/2. 5 of VOLTS/DIV switch setting. This
knob is used for comparing two waveforms and rise time measurements.
However, this knob is normall y in the fully clockwise position.
Pull out ×5 MAG
when the ×5 Mag Button is pressed, the vertical axis gain is magnifi ed 5
times, and the maximum sensitivit y becomes 1mV/DIV.
(17) 20MHz Bandwidth
The frequency bandwidth of the vertical axis is limited within 20MHz. The
function can be used to adjust the synchronization of the signals because of the
15
high-frequency inter ference.
(18) ALT/CHOP
In ALT mode, the signals on CH1 and CH2 are displayed in cycled order. And
in CHOP mode, the signals on CH1 and CH2 are displayed chopped and
displayed under the frequency of 250kHz.
(19) (20) Position
Used to move the CH1 or CH2 trace up or down on the CRT screen.
(21) Invert Push Button Switch
When the invert push button (21) is pressed, the polarit y of the input signal
applied to CH2 is inverted. This function is convenient when 2 waveforms of
different polarities are com pared, or displaying the CH1 and CH2 difference
waveform in ADD.
(22) Mode Switch
Select the vertical working mode.
CH1: Onl y the signal applied to CH1 is displayed on the screen.
CH2: Onl y the signal applied to CH2 is displayed on the screen.
Dual: When both CH1 and CH2 buttons are pushed in, the signals applied to
16
CH1 and CH2 input are displayed simultaneous l y on the CRT in either chopped
or alternate display.
ADD: Displays the algebraic sum of the CH1 and CH2 input voltage.
3.2.3 Horizontal Axis and Triggering
(23) A TIME/DIV
Selects A sweep speed from 0. 05us/DIV to 0.2s/DIV in 2 1 calibrated steps.
(24) Horizontal Position
The trace can be moved in a horizontal direction. This is used for measuring
waveform time duration .
(25) B TRIG
The knob is used to select the continuous delay or triggered delay.
In NORM, B sweep begins to scan after the sweeping time is determined by A
TIME/DIV (23) & (35).
The delay would correspond with the triggering when the knob is pressed down. B
triggering signal and A sweep would begin at the same time after the continuous delay
time.
17
(26) B TIME/DIV
The switch is used to select B sweep time within the range of 0.05 μ s～ 10μ
s/DIV and altogether 8 steps.
(27) (28) A & B ALT (Horizontal display)
The switch is u sed to select A、B sweep mode of the horizontal system. When A
and B are pressed down at the same time, the sweep lines of A and B brightened
by B would be displayed on the screen at the same time.
Brightened Part on A sweep
A Sweep
18
B Sweep
(29) Triggering Source Selector
Used to select the triggering signals.
INT: The input signal applied to CH1 or CH2 becomes the trigger signal .
CH2: The input signal applied to CH2 becomes the trigger signal .
Line: The power line frequency becomes the trigger signal source .
Ext: The external signal applied to TRIG input becomes the trigger signal.
This is used when the trigger signal is external to the vertical input
signal.
(30) Ext input terminal
It is the input terminal for the external trigger signal.
(31) Trig level knob
This control sets the amplitude point on the trigger waveform that will start the
19
sweep.
(39) Slope knob
Select the polarit y of th e slope, the trigger source waveform will start the
sweep.
(＋ ) slope is selected when the push button is out.
(－ ) slope is selected when the push button is pushed in.
Description of trigger polarit y
Pull
Description of trigger lever
Pull
(+)Slope
(+)Slope
20
Triggered with i n the solid lines.
Sweep will start when the Trigger
Level control is set to an amplitude
within the solid lines
Push
(-)slope
Push
( -)slope
(32) Trig mode switch
Auto: Sweep continuousl y runs in the auto sweep mode.
A trace will be displayed even when there is no input signal or when the
input waveform is not triggered. A stationary waveform will be displayed
21
when the input waveform is properl y triggered.
Norm: A trace will be displayed onl y when the input waveform is present and is
properl y triggered. There will be no trace displayed on the CRT if there
is no input signal or if the input signal is not synchronized.
Normal sweep is used when the input signa l's frequency is less than
25Hz.
TV-H: Effective when trig mode is set to TV, and is used when the horizontal of
the TV signal is to be synchronized.
TV-V: Effective onl y when trig mode is set to TV, and is used when the vertical
of the TV signal is to be synchronized.
Note: Both TV-V and TV-H are synchronized only when the trigger signal is (-).
(33) X-Y
The curve diagram in X -Y mode can display the phase difference of the signals
from CH1 and CH2.
CH2 Vertical Position is used to adjust the displaying positions of Lishayu
Diagram and Horizontal Position is used to adjust the position of the horizontal
axis on the screen.
22
(34) Sweep-line Separation
The knob is used to control the vertical positions of A sweep -line and B
sweep-line and it is the interval between A and B in sweeping mode.
(35) Delay Position
Used to adjust the starting position of B sweep during the A sweeping progress.
(36) VAR
Used to calibrate A TIME/DIV to the specified value when it is turned to the
end clockwise. If it is turned coun terclockwise, the sweep rate would be 1/2.5
of the specified value.
The knob is generall y in CAL position.
Pull out for ×10 MAG
If the knob is pulled out, the sweeping line
would be magnified 10 times and the
sweeping time would be 1/10 of the indicates
on TIME/DIV. Move the magnified waveform
to the center of the screen for accuracy and
23
convenience.
Waveform of MAG
Pull out for ×10 MAG operation
(37) Hold -off
Used to catch the complex signals.
3.2.4 Rear Panel
(38) Z-axis Input terminal
It is an input term inal for adjusting the sweeping line intensit y on CRT. The
code (+) indicates the decreasing intensit y and ( -) indicates the increasing
24
intensit y for the input signals.
(40) AC plug
Used to connect AC power.
(41) Line voltage converter(Rear panel): Selects the line voltage supplied to
the oscilloscope.
4. Operating Methods
4.1 Precautions prior to use
· Verify the line voltage.
Refer to the following table for the correct operation voltage ranges for the
oscilloscope. Check line voltage prior to comporting to the power source, and
25
verify it is within a voltage range listed below.
Rating
AC 220V
Operating Voltage Range
AC 198V to 242V
AC 100V
AC 99V
to 121V
Select process of the line volta ge:
(1) Remove power cable form AC input.
(2) Refer to the desiring for the power. Move the line voltage converter to the
“correct” position.
(3) Connect power cable to the AC input.
· Insure that the fuse used is an authorized product.
In order to prevent circuit damage resulting from over current, use the correct
fuse value for the primary circuit.
Power Voltage
Rated Current
For AC 220V
250V
1A
For AC 110V
250V
2A
26
If the fuse blows, check the reasons. Replace the fuse with the correct one
after repair has been made. If the fuse other than the correct one is used, not onl y
this would create conditions for failure, but also is it dangerous. Therefore, always
use the correct fuse value (In particular, never use any component wh ich does not
meet current ratings)
The fuse ratings are as follows:
(Shape) (Diameter×length)mm
SPEC
1A
Φ 5.2×20
250V F 1A
2A
Φ 5.2×20
250V F 2A
· Do not turn the intensit y too bright.
Do not excessivel y brighten the dot or trace, this not onl y tires the eyes but, if
allowed for long periods of time, it might burn the fluorescent side of the CRT.
· Exercise caution to prevent excessive voltage from being applied directl y to the
scope inputs or to the probe input. Do not appl y voltages higher than these limits:
Vertical Inputs (Direct)
400V (At DC + AC peak 1kHz)
27
When probes are used
600V (At DC + AC peak 1kHz)
EXT TRIG INPUT
400V (At DC + AC peak 1kHz)
Z-Axis Input
30V
(DC + AC peak)
4.2 How to display a trace
Check input line voltage prior to turning on the power switch. If the voltage
selector switch has been set to 120V AC, verify that input power voltage is within
the range of 108V-132V. Refer to rear panel illustrations for selection of input line
voltage. Insert the power cord into the rear panel AC receptacle, and set each
control as follows:
Power
Intensit y
Focus
AC-GND-DC
Vertical position
Mode
Trig mode
Trig source
Off ( ▍)
Rotate all the way Counterclo ckwise.
Center
GND
Center ( ×5MAG is in the off ( ▍) position)
CH1
Auto
INT
28
Trig level
Center
A TIME/DIV
0.5ms/DIV
Center ( 10MAG)( ×5 MAG) are turned Off ( ▍)
Horizontal position
After the controls have been set as above, turn on the power switch. The trace
will appear when the INTEN Knob is turned clockwise, in approximatel y 15
seconds. Adjust focus knob until the traces are at the clearest. If the oscilloscope
is not being used while the power is on, turn INTEN Knob counter clockwise to
reduce brightness.
NOTE: For normal operation, set the following variable controls to the "CAL"
position.
V/DIV VAR: The VOLTS/DIV is calibrated to the indicated values on the
VOLTS/DIV switch when turned full y clockwise.
SWP VAR: The TIME/DIV is calibrated to the indicated values on the
TIME/DIV switch when turned full y clockwise.
Set the trace to the horizontal graticule scale on the center of the screen. by
varying the CH1 position control. If the trace is slanted with respect to the
horizontal scale adjust the front panel trace rotation control until the trace is
coincident with the horizontal scale.
29
- General Check (1) Displaying 1 waveform on the CRT
If using channel 1, set the switches as follows:
Vertical axis mode switch ································CH1
Trig mode switch ········································Auto
Trig source switch ······································INT
When these settings have been completed, most repetitive signals of a
frequency greater than adjusting the trig level will synchronize approx imatel y
25Hz control and can be measured. Since the trigger mode is in Auto, the trace
appears even when there is no signal applied or when the AC -GND-DC switch is
set to GND, a DC voltage can also be displayed if the AC -GND-DC switch is set to
DC.
If low-frequency signals less than 25Hz are applied to CH1, the following
changes are required Trig mode switch ··························Norm
Adjust the trigger level control to synchronize the trace.
If using CH2 input, set these switches:
Vertical axis mode switch to ····································CH2
Trig source switch to ···········································CH2
30
All other settings and steps are the same as for displaying a waveform on CH1.
(2) When 2 waveforms are to be observed
Set the vertical axis mode switch to Dual, both waveforms now can be easily
displayed; if the TIME/DIV range is changed, the scope will automaticall y
select ALT or CHOP.
If a phase difference is being measured, the signal with a leading phase must
be the trigger signal.
(3) Displaying an X -Y mode
When the X-Y switch is pressed, the oscilloscope will be an X -Y displa y with
the signal applied to the CH1 input, as the X -Axis and the signal applied to
CH2 as the Y-Axis.
(4) Use of ADD
When the vertical mode switch is set to ADD, the algebraic sum of 2
waveforms can be displayed.
4.3 Signal connection
Pay particular attention to this, because the first step in measurement is to
accuratel y input the signal to the oscilloscope.
4.3.1 When probes are being used
31
Use the probes to accuratel y measure high -frequency signals because the input
signals are reduced to 1/10 of their value, this may be unsuitable in the case of
low-level signals. However, in the case of large amplitude signals, th e measuring
range is widened proportionally.
NOTE:
· DO not appl y signals which exceed 600 V (DC-AC) peak 1kHz.
· If a fast rise time, or a high -frequency signal is being measured. Place the
grounding lead of the probe near the point being measured. If the ground lead is
long, waveform distortion, such as ringing or overshoot, may be generated.
Handling of the ground lead
32
Good
Bad
· The actual VOLTS/DIV value is 10 times greater than the displayed value. For
example, if VOLTS/DIV is set to 50mV/DIV, the actual value is 50mV/ DIV×10
= 500mV/DIV.
· To avoid measurement accuracy, calibrate the probe as follows, and double
check prior to taking measurements. Connect the probe tip to the GAL output
connector 1kHz.If the compensation capacitance value is optimized, the
waveform will look like that shown in Fig .4-1(a). If the waveforms are as shown
in Fig.4-1(b) and(c), adjust the capacitance to the optimum value level using the
variable capacitor ( Trimmer), in the probe housing.
33
(a) Ideal condition
(b) Capacitance too low
Figure 4-1
(c) Capacitance excessive
4.3.2 Direct connection
If signals are directl y connected to the oscilloscope without using probes, take
the following precautions to minimize measurement accuracy. A bare wire may be
used for an input lead if the circuit to be measured is low impedance, or high
amplitude level . So, precautions should be taken because in many cases ,
measurement accuracy may occur due to electrostatic coupling generated from
multiple circuits or power lines. Such measurement accuracy cannot be
disregarded even at low frequency.
·In general, it is advisable to avoid using unshielded wires. If a shielded wire is
used, connect one end of the ground wire to the ground terminal of the
oscilloscope, and the other to the ground terminal of the circuit being measured.
It is desirable to use a BNC -t ype, coaxial cable as the input wire.
·If the waveform being observed has a fast rise time or is high frequency. It is
necessary to connect a termination resistance of 50 Ω to the scope end of the
cable. If the cable is particularl y long, a termination resistance of 50 Ω must be
34
connected, depending on the circuit being measured, to the scope end of the
cable. It is more convenient if a BNC -t ype, termination resistor (50 Ω ) is used.
·In some cases, the circuit under test may require a 50 Ω termination for proper
operation before measurements maybe taken.
·If a long shielded wire is used for taking measurements, the stray capacitance
must be considered. Shielded wire in general has approximatel y 100pF
capacitance per meter, the effects and the circuit being measured cannot be
ignored, and the use of probes will minimize the effects on the circuits being
measured.
·A shielded cable with no termination resistance, whose length is a 1/4 wavelength
or a multiple of a 1/4 wave length of a frequenc y within the bandwidth (100MHz)
may cause an oscillation on the 5mV/DIV range. To prevent this, connect a 100
Ω to 1kΩ resistor in series with the cable, there by lowering the Q of this
circuit or use a higher VOLTS/DIV range.
4.4 Measuring Procedures
Perform the following steps.
· Set brightness and focus to the settings that will give the best display.
35
· Display wave forms as large as possible, to minimize time accuracy.
· If probes are being used, verify capacitance compensation ( Refer to 4.3.1 [when
probes are being used] : Signal Connections for Capacitance Compensation
Methods).
4.4.1 Measuring DC voltage
Set the AC-GND-DC switch to GND , and position the zero level to a
convenient position on the screen. This position need not necessaril y be the center
of the screen.
Set VOLTS /DIV to an appropriate setting, and set the AC -GND-DC switch to
DC. The trace that is a straight line will deflect. The DC voltage can be obtained
by multipl ying the amount of divisions the line deflects by the VOLTS/DIV v alue.
For example, in the case of Fig. 4-2, if VOLTS/DIV is 50mV/DIV, the calculation
is 50mV/DIV×4.2 = 210mV (However, if probe (10:1) is used, the actual signal
value is found by multipl ying by 10; hence, 50mV/DIV ×4.2×10= 2, 100mV =
2.1V ) .
4.4.2 Measuring of AC voltage
As for measuring DC voltage, set the zero level to any place on the CRT where
36
it is convenient. In the case of Fig. 4-3, if VOLTS/DIV is 1V/DIV, the calculation
is 1V/DIV×5 =5Vp-p (However, if a probe (10:1) is used, the actual value is
50Vp-p).If a small amplitude AC signal is superimposed on an large DC voltage
the AC component maybe viewed and expanded by setting the AC -DC-GND switch
to AC, this will block the DC portion of the signal and pass the AC portion onl y.
4.4.3 Frequency and time measurement
Use Fig.4-4 as an example. 1 cycle is from point A to B, and is 2.0divs on the
screen. If the sweep time is assumed to be 1 ms/DIV, the period is 1ms/DIV ×2.0
= 2.0ms. Accordingly, the frequency is 1/2.0ms = 500 Hz. However, if ×10MAG
(×5MAG) is used, the TIME/DIV must be calculated as 1/10 (1/5) of the indicated
value.
DC voltage (After Deflection)
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Zero Level
Prior to appl ying a DC voltage
Fig.4-2
Fig.4-3
Fig.4-4
4.4.4 Time difference measurement
Set the signal that is the reference for the 2 signa ls being observed as the
trigger signal. (Refer to Fig .4-5).
1) If the signals are as in Fig. 4-5(a), Fig.4-5(b) will be displayed when the
trigger signal source is set to CH1.
2) Fig.4-5(c) will be displayed when the trigger signal source is set to CH2. In
order to measure the time delay between to signals use the following procedure:
① To find the time CH2 is delayed in respect to CH1 set the trigger signal
source to Int.
② To find the time CH1 is delayed in respect to CH2 set the trigger signal
source to CH2.
③ The delay time maybe found by counting the number of divisions from the
38
rising edge of the trigger source signal to the rising edge of the delayed signal and
multipl ying this b y the TIME/DIV setting.
In order to measure time delay, set the signal with the leading phase as the
trigger signal. If the reverse condition exists (the delayed signal triggers the
oscilloscope) the desired portion of the waveform to be observed may no t be
displayed on the CRT screen. In this case overlap the signal amplitudes with the
vertical position controls. The delay time is measured between the 50% amplitude
of the displayed signals.
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Fig.4-5
NOTE: A pulse wave contains a considerable number of high -frequency
components (harmonic waves), use the same procedures as for measuring high
frequency signals. Use probes or coaxial cable, and make the grounding line as
short as possible.
4.4.5 Measuring rise (fall) time
When pulse rise time is being measured, use the precautions detailed in the
preceding section, and observe measurement accuracy. The following relationships
exist between the rise time Trx of the waveform being measured, the rise time Trs
of the oscilloscope and the rise time tro displayed on screen.
Tro = Trx 2 +Trs 2
If the rise time of the pulse to be measured is significantl y greater than that of
the oscilloscope, measurement accuracy occurring with respect to oscilloscope
rise time can be disregarded. If the rise times are too close to each other,
measurement accuracy will occur.
Actual rise time is then Trx =
Tro 2 +Trs 2
40
In addition, for circuits where there are no waveform distortions. Such as
overshoot or sag, in general, the following relationship exists between the
frequency bandwidth and rise time.
fc×tr = 0.35
Where: fc: Frequency band (Hz)
tr: Rise time (s)
4.4.6 Complex waveform synchronization
As shown on Fig.4-6(a), if the difference in amplitudes appears alternatel y,
waveforms may appear overlapped, depending on the trigger level setting. If the
trigger level selected is the line A,B,C, D,E,F,...which starts from A. ... and the
line E,F,G, H, I.. which starts from E..... appear alternatel y, the trace will appear
overlapped as shown in Fig. 4-6(b), synchronization cannot be achieved. If, the
trigger level is turned clockwise to set trigger level to the Y' -line, the waveform
displayed on screen is shown in Fig. 4-6(c), allowin g synchronization to be
achieved.
(a) SIGNALS WAVE
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(b) TRIGGER LEVEL Y
(c) TR IGGER LEVEL Y
Fig.4-6
4.4.7Wave forms when 2 channels are being measured
If CH1 and CH2 signals have a synchronized interrelationship, or 2 signal
frequencies have a specific time relationship, such as a constant proportion, set
the TR IG signal source switch to INT. If the CH2 time is being checked relative to
CH1 signal; set trigger source to CH1 if vice versa, set the trigger source to CH2.
As shown in Fig.4-7, if a sine wave is input to CH1 and a rectangular wave to CH2,
the trig getable level range is A.
(a) if input coupling is DC
CH1
42
(b)if input coupling is AC
CH2
Fig.4-7
To magnify the synchronizing level range, the CH2 axis input coupling may be
set to AC coupling. In addition, as shown in Fig.4-8, if any one of the signals
display selector is small, set the amplitude to a sufficient level by changing the
VOLTS/DIV selector switch ( 13) (14).
CH1
CH2
43
Fig.4-8
4.4.8 TV-exclusive synchronization
① The TV wave form
In TV mode, complex signals containing the video signal, blanking pedestal
signal and synchronizing signal displayed in Fig .4-9 is clearl y observed. However,
because the waveform is complex, a special circuit is required to link
s ynchronization to the vertical s ynchronizing signal .
Fig.4-9
② Differences between competitor oscilloscopes and this oscilloscope
44
In order to ensure stabilized measurement of TV signals, this oscilloscope is
equipped with a TV-exclusive synchronizing separator circuit, as shown in the
drawing.
C
I
R
C
U
I
T
Exclusive circuitry of
The conventional equipment
Simple integrator
General circuitry
circuitry
Circuitry to video
To trigger circuit
signal trigger circuit
Operating circuitry of this
equipment
Exclusive TV synchronizing
separator circuitry
Vc
To trigger
circuit
45
F
E
A
T
U
R
E
S
Because the video
signal
is
directly
applied as the trigger
signal, synchronizing
is difficult.
Because signals are
integrated to remove
harmonic wave components, synchronizing is accomplished more easily
than in left diagram
③ Operation
Vertical frame sync is displayed
The vertical synchronizing signal
is separated after the synchronizing pulse is extracted, stable
synchronization is obtained.
Horizontal sync is displayed
MODE:TV-V
MODE: TV-H
46
TIME/DIV
0.1ms/DIV~0.2sDIV
TIME/DIV
50 μ s/DIV~0.1 μ s/DIV
Fig.4-10
NOTE: If the oscilloscope is in the TV mode, the trigger level control is not
used.This oscilloscope synchronizes onl y on( -) synchronizing signal.
(Reference)
A: Sample (-) synchronizing signal
B: Sample (+) synchronizing signal
A
B
Fig.4-11
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48