Service Manuals, User Guides, Schematic Diagrams or docs for : LG Car Audio tch-300 TCH-30~1
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TCH-300
ADJUSTMENTS
This set has been aligned at the factory and normally will not require further adjustment. As a result, it is not
recommended that any attempt is made to modificate any circuit. If any parts are replaced or if anyone tampers
- with the adjustment, realignment may be necessary.
TEST & ADJUSTMENT POINT
L ,.
t
I /
I
l_ J
IFM]
VR201
6
El
T201 O ,"
0 0
\ 0
IC201
-
Figure 1. Main PC. Board (Side A)
1 r
OS0
OGND
ORE
TP601
5
FEIFE0
00
TEI
TEO
TPGM O"
0
REF
Figure 2. Main P.C. Board (Side B)
TCH-3001
TUNER ADJUSTMENT
1. FM ADJUSTMENT
-
Power Supply PRE OUT
- 01 11
STEREO SG
-II
VTVM SCOPE
FM SSG I II
AUDIO OSC
1-n /
FM Dummy ANT.
Figure 3. FM Adjustment Connection Diagram
(1) The impedance of FM antenna terminal is 7X&.
Therefore, connect coaxial cable (3C-2V etc.) between FM SG and antenna terminal when wiring.
\
FM SSG Available Antenna
Attenuator Power Terminal
Indication Ratio Voltage
Open indication OdB 52dBf 6 dB/pV
type 60dB 652dBf 66dB/uV
Load or close OdB 11.2dBf 12dB/uV
indication type 54dB 65.2dBf 66dB/uV
.
(2) There are two kind in indication of FM SG output attenuator.
1) Attenuator with marking of 75Q open...open indication type.
2) Attenuator with marking of 75Q load or close . . . load or close indication type.
(3) FM SG output level in this FM adjustment are described as open indication type. The left table shows
relations among FM SG attenuator indication (dB), available power ratio (dBf) and antenna terminal voltage
(dB/uV) in each indication type.
NOTE: 1. BAND Switch .. .. . .. . .. .. . .. . .. .. .. . .. .. . .. .. .. . .. .. .. . .. . .. .. .. . .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. .......... FM
2. BALANCE . . .. . .. .. . .. . .. .. . .. .. . .. .. . .. .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. . .. .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. .. . .. .. .......... Center
3. TREB/BASS .. . .. .. . .. . .. .. . .. .. . .. .. . .. .. .. .. . .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. . .. .. .. . .. . .. .. . .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .....~.Center
4. Connect as shown in figure 3.
- 5. Refer to figure 1 & 2 for Adjustment Points.
FEED SIGNAL
STEP SUBJECT MEASURE OUTPUT ADJUSTMENT ADJUST FOR REMARK
FROM TO
1 Discriminator 98MHz 60dB ANTJack Between IC2Ol Pin 0 & T201 DC OV +lOmV
No Dev. Pin 0, DC Volt Meter.
FM SSG
2 FM SEEK 98MHz, 22dBpV ANT Jack Between Point SD & point VR201 DC1.6V+O.O5V
STOP 225kHz Dev GND, DC Volt Meter
-8-
TCH-300
CDP ADJUSTMENT
1. METER AND JIG FOR ADJUSTMENT
-- l-l. Oscilloscope 1-2. Test disc 1-3. Jitter meter
(Sony type 4: YEDS-43)
1-4. Low frequency oscillator 1-5. Digital frequency counter 1-6. 10: 1 Oscilloscope probe
- 1: 1 Oscilloscope probe
1-7. Focus & tracking gain adjustment jig
TP602
T 56K
A. F OSC SWI-1 0 w TEI
04 1OOK
FEI
0
0 0
F
T \
0.0047(M)
CH - 2 SWI-2 0 1 II
I
REF
oe
0 0 GND
0
0 F
J
T 22K 12K
TEO
s
CH - 1
0 FE0
F 22K 10K
NOTE : This jig is not serviceable part.
-9-
-- _
TCH-300
2. Before adjusting, preset adjustment potentiometers VR601, VR602, VR603 and VR604 center.
3. E-F BALANCE ADJUSTMENT
(1) Connect the oscilloscope to TP602 (TEO and REF).
(2) Load test disc (YEDS-43).
(3) Adjust VR602 so that amplitude above and below the zero DC line becomes equal (amplitude A=B).
Oscilloscope
A
OV DC Mode
B
k REF
A=B
4. FOCUS OFFSET ADJUSTMENT
(1) Connect the jitter meter to TP601 (HF, REF), set the input selection switch of jitter meter to "1 x " position.
(2) Load test disc.
(3) Put unit play mode.
(4) Adjust VR601 so that the jitter meter reading is minimum.
Jitter Meter
NOTE: Jitter meter must have a "1 x "
input selection switch.
-IO-
TCH-300
5. FOCUS GAIN ADJUSTMENT
(1) Connect from gain adjustment jig to wire on the main P.C. Board pin to pin.
(2) Connect audio frequency oscillator to A.F. OSC terminal and GND on the gain adjustment jig.
- Set the audio frequency oscillator output to 750Hz, ~VRMS.
Low Frequency Oscillator (A.F. OSC)
@@O A.F. OSC
L GND
(3) Connect oscilloscope to CHI, CH2 and GND on the main P.C. Board. (XV mode)
Oscilloscope
CHI : 20mV/div. AC MODE
CH2 : 2V/div. AC MODE
I-O GND
(4) Insert test disc and put unit play mode on track.
(5) Set switch SW1 on the gain adjustment jig to position "F".
(6) Adjust VR603 so that the waveform on the oscilloscope looks as shown below.
-----
Good adjustment Bad adjustment Bad adjustment
(Optimum focus gain) (Low focus gain) (High focus gain)
-ll-
TCH-300(
6. TRACKING GAIN ADJUSTMENT
(1) Connect from gain adjustment jig to wire on the main P.C. Board pin to pin.
(2) Connect audio frequency oscillator to A.F. OSC terminal and GND on the gain adjustment jig.
Set the audio frequency oscillator output to 750Hz, ~VRMS.
Low Frequency Oscillator (A.F. OSC)
Connect oscil Ioscope to CHI, CH2 and GND on the main P.C. Board (XV mode)
CHI : 20mV/div. AC MODE
Oscilloscope CH2 : 2V/div. AC MODE
(4) Insert test disc and put unit into play mode on track.
(5) Set switch SW1 on the gain adjustment jig to position "T".
(6) Adjust VI3604 so that the waveform on the oscilloscope looks as shown below.
Bad adjustment
(Optimum tracking gain) (Low tracking gain) (High tracking gain)
-12-
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