Kenwood CS 4025 HU Service Manual

Page 2

~~-~-~- WARNING A W ------- -

The following instructions are for use by qualified personnel only. To avoid electric
shock, do not perform any servicing other than contained in the operating instruc-
tions unless you are qualified to do so.

C O N T EN TS
SPECIFICATIONS .. 3
SAFETY ............... a
CIRCUIT DESCRIPTION 7

BLOCK DIAGRAM .
ADJUSTMENT ......
TROUBLESHOOTING
PARTS LIST .......
DISASSEMBLY...
PARTS LIST (ELECTRICAL) ..................
SCHEMATIC DIAGRAM/WAVEFORM .
P.C. BOARD .........

SEMICONDUCTORS .

Page 10

10

ADJUSTMENT

To obtain the best performance, periodically calibrate the
unit. Sometimes, only one mode need be calibrated, while
at other times, all modes should be calibrated. When one
mode is calibrated, it must be noted that the other modes
may be affected. When calibrating all modes, perform the
calibration in the specified sequence.

The following calibration required an accurate measuring in-
strument and an insulated adjusting flat blade screwdriver.
If they are not available, contact your dealer. For optimum
adjustment, turn the power on and warm up the scope suffi-
ciently (more than 30 minutes) before starting.

Before calibrating the scope, check the power supply
voltage.

TEST EQUIPMENT REQUIRED
The following instrument or their equivalent should be used
for making adjustment.

Test Minimum
Equipment Model Specification
. . . Impedance: More than
Dlg'ta' Multi- 11'7 10 M9, Measuring range:
Meter IKENWOOD) 0.01 V to 199 V
: 1 H t
Sine-Wave 651 B :Igfifigfzonsotanzt foltage
Generator (YHPl over tuning range
Frequency: 50 kHz to
Sine-Wave 56-503 100 MHz, Output impedan-
Genarator (Tektronix) ce: 50 fl, constant voltage
over tuning range
Output signal: 1 kHz,
Amplitude: 10 mVp-p to
Square- P 506 10 Vp-p, Accuracy: within
Wave (T E' . l i 1%, Rise time: 35ns or
Generator e tronix less
100 kHz, Rise time: 1 ns or
less
43433
0 Meter (YHP) -
Color
Pattern CG'91 1A _
Generator (KENWOODl
Sensitivity: more than 5 mV
- 475A .
Oscilloscope (Tektronix) Egggugggywrlfiszponse. More
Time-Marker TG-501 Time mark: 0.5 s to 0.1ps
Generator (Tektronix) repetive waveform
High-Voltage .
Probe - Input Impedance. 1000 MIT
- - _ Impedance: 50 o
TerITllnatIOIl Accuracy: within 3%
~ . _ 3 watts type impedance:
Termination 50 fl
Attenuator - - 20 dB attenuation (50 m
Table 1

PREPARATION FOR ADJUSTMENT

Control Settings

The control settings listed below must be used for each
adjustment procedure.

Exceptions to these settings will be noted as they occur.
After completing a adjustment, return the controls to the fol-
lowing settings.

ADJUSTMENT

NAME OF KNOBS POSITION
MODE AUTO
COUPLING AC
SOURCE VERT
VERT MODE CH1

INV OFF _-_
SLOPE .I. +
TRIGGER LEVEL 12 o'clock
CH1/CH2 POSITION 12 o'clock
CH1/CH2 ATT 10 mV/DIV

CH1/CH2 VARIABLE Fully clockwise
CH1/CH2 AC-GND-DC DC

SWEEP POSITION 12 o'clock
SWEEP VARIABLE Fully clockwise

SWEEP ATT 0.2 ms
x10 MAG OFF _-_
FOCUS Optimum position
INTENSITY 12 oclock after ad-
justment
Table 2

Adjustment
It
om VR (TC) P.c.B. Procedure

Supply voltage VR1 X68-1570 Adjust VR1 to give-8,00 V at pin P1-6.

Intensity VR2 X68-1570 MODE: X-Y
With a spot on the screen, turn the INTENSITY knob to a 9 o'clock posi~
tion and then adjust VR2 until the spot disappears.

CRT center VRIOZ X65-1380 CH2: 50 mV/DIV. GND
VvMODE: CH2
Pull and push INV to find a position of POSITION knob where the lumines-
cent line does not vary.
Leaving POSITION unchanged, adjust to the center of the screen using
VR102.

Y operating point VR104 X65-1380 Position after CRT center adjustment
Adjust VR104 to give + 57.0 V at pin P64.

X operating point VR301 X65-1380 MODE: X-Y
X-POSITION: Center
Adjust VR301 to give +68.0 V at pin P7-1.

ASTIG/FOCUS VR3 X68-157O MODE: X-Y
INTENSITY: 12 o'clock
FOCUS: 12 oclock
CH1,2: 50 mV/DIV, GND
Adjust the spot ." to the best position with the ASTIG knob and VR3.
Best position = smallest spot

CH1 Step VR2 X65-1380 CH1: GND

ATT Balance Adjust VR2 so that the luminescent line does not vary when switching
between 1 mV/DIV and 2 mV/DIV.

CHI MAG Balance VR3 X65-1380 CH1: GND
Adjust VR3 so that the luminescent line does not vary when switching
between 2 mV/DIV and 5 mV/DIV.

CH2 Step VRSZ X65-1380 V-MODE: CH2

ATT Balance CH2: GND
Adjust VR52 so that the luminescent line does not very when switching
between 1 mV/DIV and 2 mV/DIV.

CH2 MAG Balance VR53 X65-138O V-MODE: CH2
CH2: GND
Adjust VR53 so that the luminescent line does not vary when switching
between 2 mV/DIV and 5 mV/DIV.

ADD Position VR101 X65-1380 CH'I,2: GND
Bring the luminescent line to the center for both CH1 and CH2. Switch
V-MODE to ADD and adjust VR101 so that the luminescent line comes to
the center.

CH1 waveform VR5 X65-1380 Apply a 1 kHz square wave to CH1 INPUT (with the amplitude extending

shaping VR4 over 6 div.) Adjust so that CH1 ATl' waveform is flat for both 10 mV/DIV

10 mV and 1 mV/DIV ranges.

1 mV 10 mV/DIV: VHS

1 mV/DIV: VR4

I I

*l+*l