Kenwood CS 2070 HU Service Manual

Page 2

CONTENTS
SPECIFICATIONS .. 1-1 VERTICAL PREAMPLIFIER.
CIRCUIT DESCRIPTION 2-1 VERTICAL OUTPUT AMP - 61 7
BLOCK DIAGRAM ._ 2-4 SWEEP ROTARY .............. 6-1 a
TRIG SWEEP ........................ 6-1 9
MAINTENANCE 3'1 HORIZONTAL OUTPUT AM . 6~25
REMOVAL OF CASE 3'1 HORIZONTAL MODE CONTROL. 6-26
REMOVING/INSTALLING CRT .. 34 ATRIG SWITCH" MS
REPLACING SWITCHING BTRIG SWITCH .. _ 649
POWER SUPPLY ------ POWER BLANKING .. 6-30
TROUBLESHOOTING
PC BOARD AND SCHEMATIC
ADJUSTMENT ............................................................. 4.1 DIAGRAM _____________________________

ADJUSTMENT OF POWER SYPPLY AND CRT..
ADJUSTMENT OF VERTICAL AXIS (I) .....
ADJUSTMENT OF A, B TRIG AMPLIFIER.
ADJUSTMENT OF VERTICAL AXIS (II)
ADJUSTMENT OF HORIZONTAL SWEEP .
ADJUSTMENT OF X-Y OPERATION ...........
ADJUSTMENT OF TRIGGERING
OPERATING CHECKS .................

TROUBLESHOOTING ..........................

PARTS LIST AND DISASSSEMBLY..
MAIN SHASSIS ................
VERTICAL ATTENUATOR

VERTICAL ATTENUATOR.

VERTICAL PREAMPLIFIER... .. 74

VERTICAL OUTPUT AMP

SWEEP ROTARY,

TRIG SWEEP ....... . 7-10

HORIZONTAL OUTPUT AMP..,... 7-12

HORIZONTAL MODE CONTROL . 7-14

ATRIG SWITCH ..... . 7-16

B TRIG SWITCH .. . 7-18

POWER BLANKING 7-20
SEMICONDUCTOR 8-1

Page 20

ADJUSTMENT

Item

Adjustment

P.C.B

Test

Control

characteristics,

. ' Ch k
Control No. Equipment Setting Adjustment and 5° 2 Illustration Remark
CH4 Waveform TC8(Medium X73-1320 PG-506 H.DlSPLAY: A (1) Apply 1kHz and 1 MHz square wave signals of fast rise time to both CH3 90,49 div or TC7 (X73-l320)
Shapping range) V.MODE: GUADALT and CH4 INPUT and take the same steps as in (1) above to shape the Before making ~1 MHz
31%;; X73-1320 A TRIG sounce: EXT CH3 waveform. -- -- ~- wave shape, be sure to ad-
9 a TFllG SOURCE: EXT CH4 34320) iust input capacity EXT
A SWEEP TIME/DIV: 0.2ms Overshoot less than 8% CH4 (34)
B SWEEP TIME/DIV: 0.2ms
1 MHz
square wave
)
Adjustment of CH3 Input TC1 X77~1 130 43433 A TRIG SOURCE: EXT CH3 Make adjustment so that the input capacity of CH3 becomes equal to the ; .
Capacity B TRIG SOURCE: EXT CH4 value of CH1 5mV range (ZBpF 1-2pF). { Be sure to make adiustment
of input capacity after mak-
ing 1 kHz square wave
waveshape.
Adjustment of CH4 Input TC4 X77-1130 Adjust the input capacity in the same manner as CH3. k d
I Be sure to ma 5 a just~
Capacity < Check >
e . . men! of input capacity after
Check the input capacity In the same manner as CH3. making 1 kHz square wave
less than 8%. waveshape
ADJ USTMENT OF VERTICAL AXIS (ll)
check of1 MHz Square H.DISPLAY: A (1) Check the squarewave characteristics of CH1 and CH2 5mV range. Turn < Note>
wave Characteristics A. Tale SOURCE: V,MODE the VOLTS/DIV knob for each channel to adjust the oscillator output so As the VOLTS/DIV is
Square wave PG-506 A.SWEEPTIME/DIV: 0~2u5~ that CH1 and CH2 will produce a waveform of 6 div. respectively. "3wa rotated, the
Characteristics 50S) Termi- 005% (2) The overshoot must be less than 8% for each range. amplitude ff 6 divs can-
of CH1 and CH2 nation THIGMODE: AUTO not be obtained amplitude
A COUPLING: AC
Square wave H. DISPLAY: ALT Apply a 1 MHz squarewave signal to CH3 and CH4 INPUT and see if the
Characer'stics V.MODE: QUAD. ALT overshoot is less than 8% at this time.
of CH3 and CH4 A.TR|G SOURCE: EXT CH3 I
B TRIG SOURCE: EXT CH4
CHeck of CH1 and CH2 86-503 H. DISPLAY: A (1) With CH1 VOLTS/DIV set to 5 mV, apply a sine wave signal of 50kHz to
Frequency Characteristics 50:2 coaxial TRIG MODE: AUTO INPUT and adjust the oscillator output to produce a waveform of 6 div on
cable Ar TRIG SOURCE: V. MODE the CRT screens
(BNC-BNC) A COUPLING: AC (2) When the frequency is varied to 70 MHz with the oscillator output remain»
509 ZOdB CH1, CH2 AC-GND-DC: DC ing unchanged. the amplitude on the screen must be over 4.25 div and
attenuator A SWEEP TIME/DIV: Zus~ there must be no sudden dips and peaks during attenuation.
SODTermi- 005,5 (3) Perform the same operations for CH2.
nation [Frequency characteristic ( 70M Hz: less than -3 dB]
(4) When the specification, are not satisfied, readjust the 1 MHz squarewave

4-10

Page 24

. ADJUSTMENT

TRIG. MODE: AUTO
A VAR: CAL

seft end of. the graticule on the screen and the 11th peak with the right)
end.

(3) Next Rotate the A SWEEP TIME/DIV to 5 its and apply a 5 us time
marker to CH1 INPUT and adjust VR1 in the same manner as (2)

(4) Next. A SWEEP TIME/DIV to 0.1ps and with 0,1 [is time marker to CH1
INPUT, adjust TC1 in the same manner as (2)

,t Adjustment P.C.B Test Control . c k Illustration Remark
em Control No. Equipment Setting Adjustment and hat: ( V
l
Adjustment of 3 Swap van x74t1320 3.501 HIDISPLAY: ALT (1) Apply a marker signal of 0.5 ms to CH1 INPUT and align the first peak ofA l
Position VMODE CH1 sweep to the leftmost division of the CRT screen. (
ATRIG SOURCE: v MODE (2) Operate é TRACE SEP to separate A sweep and B sweep and set A.
a TRlG SOURCE: CH1 VAR to CAL-
A,B SWEEP TIME/DIV: 0.5m: (3) Make adjustment so that the starting point of B sweep is aligned with that
TRIG MODE: AUTO of A sweep in the horizontal position.
A. B TRIG SLOPE: + < Check>
A: B 'NTEN: Fully CW Operate : TRACE SEP so that A sweep and B sweep are superimposed on one
DELAY T'ME MUD-'3 020 another and make sure that their starting points coincide with each other,
Adjustment of X10 MAG VR13 X74-1320 TG-501 H,D|SPLAY: A (I) Apply a marker signal of 01 ms to CH1 INPUT to produce a waveform of
Gain VMODE: CH1 Vertical amplitude of about 2 div,
A TRIG SOURCE: VMODE (2) Align the first peak of the marker signal with the left end of the graticule
A SWEEP TIME/DIV: 0i1ms line on the CRT screen and the 11th peak with the right end and pull the
TRIG MODE: AUTO X10 MAG switch.
CH1. VOLTS/DIV: 1V (3) Make adjustment so that the peak-to-peak distance is 10 divi ;
CH1. AC-GND-Dc: Dc
10 times $596
x10 MAG
Adjustment of X10 MAG VR14 X74-1320 H. DISPLAY:A (1) Apply a marker signal of 0.5 ms to CH1 INPUT to produce 3 peaks
center V" MODE: CH1 waveform on the CRT screen. Ali n with center vertical raticule line
ATRIG SOURCE: V, MODE (2) Operate 4 > POSITION to bring the central peak to the vertical center 9 9 '
A SWEEP TIME/DIV: Otlms graticule line on the screen,
A: VAR: CAL (3) Make adjustment so that the waveform will be aligned with the vertical
TRIG. MODE: AUTO center graticule line on the screen when the FINE knob is pulled out (X10
A,TRIG SLOPE: + MAG position).
< Check > \
Repeatedly push and pull the FINE knob to make sure that the center of the
waveform does not move.
Deviation less than I div.
l
I
Adjustment of MAG Recheck the center at X 10 MAG and Gain.
Center and Gain
Adjustment of A VR2 (50 ms) X74-1320 TG-501 H. DISPLAY: A (1) With A. SWEEP TIME/DIV set to 50 ms, apply a marker signal of 50 ms
_: Sweep Time 50 ms,5us VR1 (511.5) Vi MODE: CH1 to CH1 INPUT,
~ and 0.1 ,5 TC1 (0.1;:5) At TRIG SOURCE: V. MODE (2) Adjust VRZ so that the first peak of the marker signal is aligned with the

Page 93

X75-1120-01
(VERTICAL ATTENUATOR

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Location of Parts in the Rotary Switch

Page 105

9 BOARD

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I
i
I CAUTION

Because the silk symbols in P42 and P57 are reversed,

please refer to the Schematic Diagram.

X74-1310-01
(SWEEP ROTARY UNIT)