Fisher DAC-204 - CD Mechanism Exploded View; Adjustment Procedures

CD MECHANISM EXPLODED VIEW CD MECHANISM PARTS LIST ADJUSTMENT PROCEDURES
Ret. Part No. Description arty PRECAUTIONS REGARDING ADJUSTMENT SETTING OF INITIAL POSITION OF VOLUME
@ Adjustment is performed in 1. The variable resistors are set to the following initial
CD MECHANISM the indicated order. positions.
1 134-0-4009-04001 Pick-up Assy T 84.5 a) 1 @ When adjustment is mode P4101 (E-F BALANCE) ...............-. Mechanicai Center
2 4-2319-78750 Leaf Switch (Pick-up Limit) [SW7] : for one item, check the other P102 (FOCUS GAIN) ..... .... Mechanica! Center
4 45279-71421 Motor (Diec) (M2) : items which follow. P103 (TRACKING GAIN) ”... Mechanicat Center
4 4-5279-71431 Motor (Sled) [M1] 1 : ical
5 131-2-4220-10507 Ring Snap { @ The iaser pick-up has P104 (KICK GAIN) ........ — Mechanical Center
6 141-0-3119-26601 Chassis Assy 1 already been’ precisely P105 (FOCUS OFFSET) Mechanical Center
7 141-2-5229-01300 Turntable 1 adjusted. Do not touch its ; P106 (TRACKING OFFSET) .......:.. Mechanical Center
8 141-2-5519-66400 Gear Pick-up 1 mounting screws controls. P107 (DAC) ............55 isedviahledes tee Mechanical Center
9 141-2-5519-66500 Gear Load D 3!
10 141-2-5519-66600 Gear Pinion 1 . FREE RUN FREQUENCY ADJUSTMENT
ee : © Refer to the schematic diagram and printed circuit board. 1. Turnon the power switch and set the unit to the STOP mode.
3 141-2-5519-67000 Gear Support Pick-up 1 © The ground point for the measurement equipment is the test 2. Connect the frequency counter between test pin VCO of
14 141-2-7319-76000 Slide Base Pick-up 1 point indicated as GND. connector CN10 and test pin GND (use probes).
15 141-2-7319-76100 Stide 1 3. Rotate the core of the PLL OSC coil (T102) with a plastic
16 141-2-7519-76600 Shaft Gear Load 1 REQUIRED EQUIPMENTS screwdriver so that the frequency counter indicates
7 141-2-7519-76700 Shatt Pick-up 1 4.3218MHz.
18 141-2-8259-13800 Guide Slide Base Pl 1 . Paes Caalaceae
18 141-2-8599-57500 Spring Plate 1 FOCUS OFFSET ADJUSTMENT
20 —-141-2-8558-15100 Spring Slide Base P 1 © Frequency Counter ;
ay 411031 1605 SCR BIN 2.6X6 3 @ Signa! Generator 1._ Turn on the power switch and set the unit to the STOP mode.
22 411 021 2704 SCR S-TPG BIN 2.6X6 1 e Plastic Screwdriver 2.. Connect a DC Voltmeter and oscilloscope between test pin
23 141-2-4219-42300 Screw 2 © Diffraction Grating Adjustment Jig FC of connector CN14 and test pin GND. ;
24 141-2-4219-05400 Screw Washer M2.0x4 2 e Test Disc (SONY:YEDS4) 3. Adjust P105 so that the indication on the DC Voltmeter and
25 141-2-4219-36700 Set Screw V-cone M2.0X4 1 @ Test Disc (SONY: YEDS7) oscilloscope is OV+10mvV.
26 411023 3303 SCR S-TPG PAN 2.6X8 1
ar 411019 9401 SCR PAN PCS 1.7K2.5 7 CHECKING FOCUS ERROR SIGNAL TRACKING OFFSET ADJUSTMENT
NOTES: Checking the focus error signal of the pick-up allows for an 1. Turn on the power switch and set the unit to the STOP mode.
1. Parts order must contain Model Number, Part Number and evaluation of the pick-up. Be sure this is carried out before 2. Connect a DC Voltmeter and oscilloscope between test point
Description. repair. TC of connector CN14 and test pin GND.
2. Ordering quantity of screws and resistors must be multiple of 1. Turnon the power switch and set the unit to the STOP mode. 3. Adjust P106 so that the indication on the DC Voltmeter and
10 pes. 2. Connect an oscilloscope between test pin FE of connector oscilloscope is OV+50mV.
CN15 and test pin GND. (Set the time axis to 0.5
seconds/division.) NOTE:
3. Connect the +10V supply voltage to test pin TP3 through a This adjustment should be mode again after the adjustment
47kO. resistor. of Tracking Gain.
47k0
+10V -—CD—~ TP3 ADJUSTMENT OF DIFFRACTION GRID
This unit uses a three beam
method for the laser pick-up.
Diffraction grid adjustment
involves adjusting the position of
the E and F beams in relation to
the main beam so that they are
in the same line.
4. Press the EJECT 1 button and place the test disc YEDS4 on
the table load. Press the PLAY button.
5. The waveform shown below is displayed six times on the
oscilloscope, Check that the p-p voltage is about 8V and that
the top and bottom of the waveform are symmetrical.
Repeated six times
The following is the adjustment procedure. This is a precise
adjustment and must be made carefully.
{When recorded on a memory scope)
: 1.. Turn on the power switch, place test disc YEDS4 on the
table load and set the unit to the STOP mode.
So. This aliows tor Son enon : 2. Short test pins TEST1 and GND of connector CN16.
to be made. The pick-up is Repeaters (>) = 3. Short test pin TP1 and test pin GND. Pass test pins E
faulty if confirmation cannot :
(TP13) and F (TP14) through the band pass filter, and
connect to the channeis of the dualtrace oscilioscope. The
* p-p voltage of 8V ground is obtained from test point GND.
* + and — voitage roughly same
be made.
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