Akai AC 10 Service Manual

Page 2

SAFETY INSTRUCTIONS

PRECAUTION DURING SERVICING

1. Parts identified by the AH) symbol are critical for
safety. Replace them only with the parts number
specified.

2. In addition to safety, other parts and assemblies
are specified for conformance with such regula-
tions as those applying to spurious radiation.
These must also be replaced only with the spei»
cified replacements.

Examples: RF converters, tuner units, antenna
selector switches, RF cables, noise blocking capa-
citors, noise blocking filters, etc.

3.Use specified internal wiring. Note especially:

1) \Mres covered with PVC tubing
2) Double insulated wires
3) High voltage leads

4. Use specified insulating materials for hazardous

live parts. Note especially:

1) Insulation Tape

2) PVC tubing

3) Spacers (insulating barriers)

4) Insulation sheets for transistors

5) Plastic screws for fixing micro switches

5. When replacing AC primary side components
(transformers, power cords, noise blocking capa-
citors, etc), wrap the ends of the wires securely
around the terminals before soldering.

entail?

6. Make sure that wires do not contact heat produc-
ing parts (heat sinks, oxide metal film resistors, fu-
sible resistors, etc.)

7.Check that replaced wires do not contact sharp
edged or pointed parts.

8. Also check areas surrounding repaired locations.

9.Make sure that foreign objects (screws, solder
droplets, etc.) do not remain inside the set.

MAKE YOUR CONTRIBUTION TO PRO-
TECT THE ENVIRONMENT

Used batteries with the ISO symbol for 0:7
recycling as well as small accumulators %&
(rechargeable batteries), mini-batteries

(cells) and starter batteries should not be thrown into
the garbage can. Please leave them at an appropri-
ate depot. All other household batteries can be
thrown out with the household waste.

SAFETY CHECK AFTER SERVICING

After servicing, make measurements of leakage-
current or resistance in order to determine that ex-
posed parts are acceptably insulated from the sup-

ply circuit.

The leakage-current measurement should be done

between accessible metal parts (such as chassis,

ground terminal, microphone jacks, signal input/out-

put connectors, etc.) and the earth ground through

a resister of 1500 ohms paralleled with a 0.15 uF

capacitor, under the unit's normal working conditions.
The leakage-current should be less than 0.5 mA rms
AC. The resistance measurement should be dore be-
tween accessible exposed metal parts and power
cord plug prongs with the power switch (if includ-
ed) ON. The resistance should be more than 2.2
M Ohms.

PRECAUTIONS IN REPAIRING

When repairing or adjusting the unit please note the

following points.

1. Do not put excessive pressure on the mechanical
part (operation part), including the pick-up block,
as extremely high mechanical precision is required
in these parts.

2.When the base is removed for repair or adjust-
ment, make Sure that are no metal objects in the
narrow gap between the RC. board or the mecha
parts and the base.

3. The Micro-Computer and the CD signal process-
ing le can be damaged by static electricity or
leakage from a soldering iron during repairing.
While soldering, please take the precautions
against leakage as in the illustration.

GND

4. Do not loosen any screws in the pick-up block.
When handling the pick-up block, please refer to
the points to NOTE when replacing the pick up
block.

5. TO avoid hazardous invisible Laser Radiation, DO
NOT look at the Laser Beam (Objective lens)
directly.

6. On models for some countries, laser warning
labels are affixed on the unit and inside of the unit,
as shown below. For your safety, read these labels
carefully when repairng or adjusting the unit.

(EUROPE, SCANDINAVIA, UK and AUSTRALIA)

Label affixed on the rear panel of the unit

CM] KN: Immune oat
wmmmmmmm

Wm
alga-manunfirnm
win-mum

VAN "Am. a mm was
I as} um mm vacuum:

Label affixed near the LASER pick up of the unit.

Page 17

DESCRIPTION OF FUNCTIONS

7. DEFECT CIRCUIT

The FtFI signal bottom, after being inverted, is held with two time constants. one long and one short. The
short time-constant bottom hold is- done for a disc mirror defect more than 0.1 m sec. The long time-constant
bottom hold is done with the mirror level prior to the defect. By differentiating this with a capacitor coupling
and shifting the level, both signals are compared to generate the mirror defect detection signal.

0618
0.033 u

IOflOT M9220

DEFECT
l _____ COMPARATOR
DEFECT AMP 0823 BOTTOM HOLD
3} 0.01 it
a RFO
b DEFECT
AMP
c BOTTOM HOLD (1) BOTTOM
Soid Line (301 HOLD (2)
Dotted Line cc2

e DEFECT

1.4/4 secMAX

8. FOCUS SERVO SYSTEM

The below is a block diagram of the focus servo system. When F83 is switched on, the high frequency gain
can be reduced by forming a low frequency time constant through a capacitor connected across pins 0 and
(i3 and the internal resistor.

The capacitor across the pin (9 and GND has a time constant to raise the low frequency usually playback
condition. The peak frequency of the focus phase compensation is inversely proportional to the resistor
connected to pin (3 (about 1.2kHz when the resistor is 470K.Q).

The focus search peak becomes about :1.1 Vp-p with the above constant. The peak is inversely
proportional to the resistor connected across the pins ® and @. However, when this resistor is varied. the
peaks of track jump and sled kick also vary.

The FZC comparator invert inout is set to 2% of the difference between the reference voltage Vcc and
VC(Pin 1):2% x (Vcc-VC).

|0801 KA9220

18K F550 To iceoa
PHASE KAszsa®
R529 t COMPENSATION R517 (FOCUS
5.6K 100KACTUATOR
DFlNER)
Vret
R606
180K
Verf 0813
33/16

081 1 470K
0.1 n W) Vcc V

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