LG GoldStar FMH-49A User manual

GoldStar
COMPACT
DISC
STEREO
SYSTEM
SERVICE
MANUAL
CAUTION
BEFORE
SERVICING
THE
rie
READ
THE
“SAFETY
PRECAUTION”
IN
THIS
MANUA
MODEL:
FMH-49A/FMH-49L
FFH-49A/FFH-49L
GoldStar

CONTENTS
1; SSACETYV. PRECAUTION eis se vate ie Bae oa ue Sea Te Ae ns Ses 2
>. SERVICE ING LRUC TIONS sn% Ses) teres ein aan a iin eee een ends jas ams om waes as Bh 3
FLIES DECIFIGAIIONG on sone tr od ae athe Seared eee Ret Re eee aleary We eRe S 4
4s ADJUSTMENTS s:oe% otto Ee ate Sie pags) e 1s sleequetauten OU aig ate dotted aus ee atelaigtien Seng 6
5. DESCRIPTION OF FUNCTIONS +2526 eosee se ere ence iets cians bua elie, ciel Pee 15
& WAVEFORMS OF MAJOR CHECK POINTS au citnsd Aces ace ASS cate ae aerate he aGe Rete g aes 21
7. BLOCK DIAGRAM
@CD: SECTION deseo oo ee ote See at eat ee etn ee ae ae a nes Winger irs de 23
@ AUDIO SECTION Brean en ios iad eS reba eclenoibek Whee eulsets He pulsed tla Qian Pcie ah 24
8. SCHEMATIC DIAGRAM
@ MAIN: CIRCUIT 2 oe fine oct oe ee de Se es ea pe as 25
@ FRONT CIRCUIT chet criti eer Ste igen 4 dedads che sa ed Pou Leora a Mae, 26
@ DECK GIR GUI eesti trees a ete ec Ne eda dteat a Bune Sacer ss oN RB teen bot 27
@ CO. CIRCUIT x3 elie Sopa ak eee bare canta EER, Ba eg he eh Sa epee Le Bae ek 28
O- POR LAYOUT cies toes tee idk ane Tse Maar dates tad Seat dlea sin dae ivgk oawiaddigatcates 29
10. WIRING DIAGRAM
@CD-SECTIONS itis ot as Ses ch ie eee ee antes has sale teens aoa 32
@AVDIO SECTIONS 50-5854 hoe a eoeale ws ea4e es Raat gi asin eaten SODew eee tes eee 33
44 INTERNAL BLOCK DIAGRAM OF ICS atari itee en Sean eden ee a eee eas 34
12. EXPLODED VIEW/PARTS LIST
@ CABINET 20 ies hence kre eae ae ee ne ete net cou tite nh eee rida hea iiaats ute 38
@ TAPE DECK MECHANISMS ote trsSaealvenreta ck anda tot chistes tee eS carats tas 39
@ TAPE DECK. MEGHANISMLO/D «sx xakencctat cis teindis ans cele al ede teat aaa de eens 40
SCO MECHANISM Ht eesie eta chert tau yt reneie sane e ire ena dam ide Gaieatite aoe Se 41
@ RECORD PLAYER MECHANISM (OPTION) 2s 2ere0 9 erase iets Ce sige Megs wep wins 2 a ata 42
123. PEPLACEMENT PARIS LIOD is tReet ee Sens ds Lehi u beeen tide sag eGnes seeta spe bauer 43
SAFETY PRECAUTION
Many electrical and mechanical parts in this chassis have special safety-related characteristics. These
characteristics are often passed unnoticed by a visual inspection and the protection afforded by them cannot
necessarily be obtained by using replacement components rated for higher voltage, wattage, etc.
Replacement parts which have these special safety characteristics are identified in this manual, electrical
components having such features are identified by a A\ in the schematic diagram and the parts list. Before
replacing any of these components, read the parts list in this manual carefully. The use of substitute
replacement parts which do not have the same safety characteristics as specified in the parts list may create
chock, fire or other hazards.
PROTECTION OF EYES FROM LASER BEAM DURING SERVICING
This set employs laser. Therefore, be sure to follow carefully the instructions below when servicing.
WARNING!!
WHEN SERVICING, DO NOT APPROACH THE LASER EXIT WITH THE EYE TOO CLOSELY. IN CASE IT IS
NECESSARY TO CONFIRM LASER BEAM EMISSION. BE SURE TO OBSERVE FROM A DISTANCE OF
MORE THAN 30cm FROM THE SURFACE OF THE OBJECTIVE LENS ON THE OPTICAL PICK-UP BLOCK.
—-2-

SERVICE INSTRUCTIONS
PRECAUTION TO REPLACE OPTICAL BLOCK
PICK-UP Assy P.C.B CD PICK-UP Assy
AEELSEOTEETIIEDEETEBEEEEEEEEEE IEG,
Yy y
3 7 A q
3
vA
vA
vA
AYA
vA
A
4%
PATA
Z Zk“
Gerssereetl Yes,
Body or clothes electrostatic potential could
ruin laser diode in the optical block. Be sure
ground body and workbench, and use care
the clothes do not touch the diode.
AAAAR ARRAN
1) After the connection, remove solder
shown in right figure.
SN 6
ww
vA
Z
4
vA
Z
Z
Z
Z
4
4
3
Zz
To
prevent
electrostatic
breakdown,
laser
diode
and
ground
are
connected
with
solder.
NOTE
:
When
removing
solder,
be
sure
to
use
a
grounded
solder-iron,
to
prevent
electrostatic
breakdown.
> | Ground
CAUTION FOR HANDLING THE OPTICAL PICK-UP
The
laser
diode
in
the
optical
pick-up
block
may
suffer
electrostatic
breakdown
because
of
the
potential
difference
generated
by
the
charged
electrostatic
load,
etc.
on
clothing
and
the
human
body.
So,
when
handing
a
pick-up,
the
procedure
for
grounding
as
follows
is
required
to
prevent
damage
caused
by
static
electricity.
1. Grounding for Human Body.
Be
sure
to
put
on
a
wrist-strap
for
grounding
(with
impedance
lower
than
10°2)
whose
other
end
iS
grounded. The strap works to drain away the static electricity build-up on the human body.
2. Grounding For the Work Table.
Be
sure
to
lay
on
the
table
a
conductive
sheet
(with
impedance
lower
than
10°.2)
such
as
a
sheet
of
copper,
which is grounded.
3.
As
static
electricity
build-up
on
clothes
is
not
drained
away,
be
careful
not
to
let
your
clothes
touch
the
pick-
up.

SPECIFICATIONS
1. AMP SECTION
cD:
Power
Output:(4.0:-2'
channel.
THD.
10%):
#3
vee
eet
eet
eet
ee
20W
+
20W
@
MEAS
TS
seestsiss:
ays
Reuse
ag
ahaa
Moa
ee
ok
te
and
Venn
Bak
coh
enc
Sor
aaa
gece
RA
Bona)
S
AG
aot
eee
pane
a
gd
Lg
Mah
ole
tetra
ee
0.5%
@
Frequency
Response
(3dB
down)
«+--+
++:
22sec
cette
ence
cee
teen
ees
20Hz~30kHz
(@:
Signalto-noise
Aalo
>
cers
223.3
useee
eas
pap
vest
saya
hea
eRe
ded!
Gaebidaute
Sdoeureeyeles
85dB
G)
Crosstalk
100H2/1KH2Z/10KHZ
------
+62
eee
eee
eee
eee
eee
eee
50dB/50dB/50dB
2.
TUNER
SECTION
1)
FM
C)
Frequency
Range:
40140
10+
ete.
0
el
cht
vead
pag
one
wae
h
eee
eet
87.5MHz~108MHz
@)
Intermediate
Frequency
3:6
sta
doreee
Hert
oes
ias
ase
aaa
dd
ot
Bee
bdgabya
as
saeds
10.7MHz
@
Sensitivity
9OMHZ/98MHzZ/106MHz
-
+--+
+0
eee
eee
eee
ee
8dB/8dB/9dB
@
Signal-to-noise
Ratio
98MHz
(Mono/Stereo)
---
+--+.
-
+6...
ete
cee
eee
70dB/65dB
(5)
Image:
Rejection
S8MIZ
ss
2iace
sa
ews
2
geld
Row
a
ord
Mynde
TAS
eienas
edaeea
dg
ay
Meda
e
bs
45dB
©
IF
Rejection
98EMHZ
«+--+...
6
ec
ence
eee
ees
60dB
@
Distortion
98MHz
(Mono/Stereo)
«+--+
+++
2
ieee
eee
eee
eee.
0.5%/0.8%
Frequency
Response
(-SdB)
c+
os
se
det
esas
Mees
ee
eg
eee
ees
30Hz~14,000Hz
@
Separation
100kHZ/1kHZ/10KHZ
+--+
+022
tee
ere
eee
eee
eee
eee
30dB/35dB/30dB
2)
MW
CPs
Frequency
Range
snastsesbe
roti
epee
sesicy
aes
ene
(eee
casei
sae
522kHz~1,611kHz
(2)
Intermediate
Fréguenty
<a
460154as
Sees
ventas
sas
sendiond
ge
ey
Ne
ey
pope
aks
Ans
450kHz
@
Usable
Sensitivity
603KHz,
999KHzZ,
1404kKHz--
+--+
6
ee
eee
eens
55dB
(4)
Image
Rejection
1,
AGA
esx
nwt
at
ik
og
cee
ete
at
die
asc
aie
tide
p
lan
Bate
id
Goh
cela
ead
be
30dB
©)
IF
Rejection
GO38KH2
«+
+--+
nee
ene
ees
40dB
©
Selectivity
QOOKHZ
«+++
cece
eee
35dB
@
Signal-to-noise
Ratio
Q99KHZ
-
«+--+
eee
ees
35dB
Distortion
S9QKAZ
Hs
22sec
hee
Lo
ie
ea
Se
Boies
ote
Oh
ee
ehalba
lid
yl
DEG
Mas
walle
ley
Logs
2.0%
@
Frequency
Response
(-6dB)
-----
+--+
201-2
eee
eee
eee
eee
eee
eee
70Hz~2,300Hz
3) LW (OPTION)
@
Frequency
Range
+--+
+--+.
0-00.
e
eee
eee
cee
eee
cee
nena
sense
tues
en
ees
144kHz7~288kHz
@
Intermediate
Frequency
aie
B
aa
nk
pate
igh
teh
Bie
Marston
Sata
ee
Goblace,
Bas
ntaae
ad
lela
Wks
sabe
a
aoe
A
eee
a's
450kHz
@
Usable
Sensitivity
164kHz,
200kHz,
254KHz
+--+
2000
e
ees
64dB
@
Image
Rejection
164kHz,
200KHz,
254KHZ
«+--+
+60
eee
eee
ee
eee
eee
ee
30dB
(5)
Selectivity
2OOkKHZ
«<i
ene
cede
See
es
thee
ee
ted
ecg
daa
aiseas
weanqa
bag
iy
hs
aad
«
35dB
©
Signal-to-noise
Ratio
200KHZ
-
+--+
eee
e
eee
ee
35dB
®
DIStOMION
+6:
260
be
oe
es
og
eg
tee
eet
St
a
lw
Kaen
dd
We
ene
Sel
ws
aa
ee
as
Bae
dates
2.0%
Frequency
Response
(-6dB)
---------++5+--
6.
tees
te
eee
eee
eee
eee
eee
eee
ees
70Hz~2,300Hz

3. DECK SECTION
@
Tape
Speed
(MTT-111)--
+00
eee
eee
ee
eect
eeaes
3kHz+1%
@
Wow
and
Flutter
(MTT-111)
6-6
ee
eee
ee
eee
eens
0.25%
@)
Fast
Forward
and
Rewind
Time
(G-60)
+25
665
fa
wee.
ele
eee
dea
eens
ede
eine
epee
beet
ee
150sec
@
Frequency
Response
(4dB
Range)
i-+
226+
6+
sees
se
eee
cae
een
eka
Rema
dived
aeons
125Hz~8kHz
©)
Signal-to-noise
Ratio
(Playback/Record)
«+--+
+++ 02s
eerie
ere
eee
eee
eee
eee
ee
50dB/45dB
© Distortion
(Playback/Record)
«+--+...
6s
ieee
ete
eee
ees
1%/2%
CT)
GLOSS
HAI
32
ey
terested
eran
se
este
ast
dita
dane
Dey
eecopsardee
Meds
WAR
nln
ila
Staal
WR
dee
tuti
tate
Git
eae,
55dB
Separation:
+4
+e
ee
see
eee
ieee
Se
EN
VD
te
ies
Peles
beds
uae
dewed
wa
Podge
e
we
40dB
@)
Erase
Ratiove
iss
tie
feces
etd
be
SR
ed
ges
&
Bw
Ea
a
Pan
ties
Mela
sla
ee
60dB
4.
CDP
SECTION
CD)
Frequency
Response
(80Hz~18kKHz)
s<<4
os
ee
eee
tee
eek
gad
ie
Pewee
eee
y
Edda
aay
+1dB
@)
Signal-to-noise
Ratio
---
+--+...
eee
eee
eee
68dB
@
Dynamic:
Range
<6s:-e6
sete
eee
eet
eta
See
dae
eh
eed
eee
eens
ea
les
ekg
ee
©
65dB
@
Tet
SB)
ech
eset
fee
lia
ae
Goan
chiige
eee
eB
atlas
G2
Sth
tips
each
ech
oe
emilee
ede
EE
at
Ne
ots
att
ih
ae
0.5%
S)
Separation
622
heise
wie
ear
pe
Tae
Wa
Gleg
bedaee
glebak
log
ahd
dueetoeadge
inaugadd
4
edge
able
«
35dB
5. RECORD
PLAYER
SECTION
(OPTION)
CD
Wow
and
Flittens
sss
eae
aie
tga
nee
ed
Sul
edn
dete
eh
s
26
wldage
By
ee
Sa
Pee
ate
0.2%
@
Speed
(33
1/3,
ABIPM)
«oe
cet
eee
eee
+1%
@
Signal-to-noise
Ratio
-----
+...
ee
ee
ee
ee
rennet
een ees
40dB
G@
Separation
2-098
88
he
ste
es
aiks
ee
an
ewes
ing
elle
aia
Qearauce
ate
aeons
CEA
nace
d
15dB
(©)
Channel
Difference:
-----
+--+.
cece
eee
eee
eee
1dB
@
Frequency
Response
---
+--+
++
essere
eeee
eed
acts
Pd
wal
a
acted
Sites
ea
ota
een
ceed?
fo
50Hz~15kHz
6.
GENERAL
@
Power
Requirement
----
+--+:
+
see
cree
e
teen
eee
eee
eee
Refer
to
the
back
panel
of
unit
@
Power
Consumption
«+--+...
20sec
eee
eee
ce
eee
ee
eee
nent
n
es
20W
@
Dimension
(Net:
WXHXD)
+.
06sec
eee
ete
ee
teen
eect
ee
eee
c
ee
tee
t
ene
360
x
323
x
315(mm)
NOTE
:
Specifications
are
subject
to
change
without
notice
in
the
course
of
product
improvement.

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.
IMPORTANT
1. Check power-source voltage.
2. Set the function switch to band being aligned.
3. Turn volume control to minimum unless otherwise noted.
4. Keep the signal input as low as possible to avoid AGC and AFC action.
TEST & ADJUSTMENT POINT
Figure 1. MAIN P.C.BOARD
VR805
VR804 [suco
Loi
VR803 EEixe!
VR802 ar:
Figure 2. CD P.C.BOARD

TUNER
ADJUSTMENTS
1. FM IF ADJUSTMENT
1)
As
The
Distortion
Meter
Is
Not
Used
DC
Voltmeter
Connect
to
both
side
of
the
R122.
“Frequency | Adjustfor [Adjustment |
98MHz | DC OV+10mv
Repeat step 1 several times.
DC
UNIT R122 ©) VOLTMETER
[250B |
Figure 3. FM IF Adjustment Connection Diagram
2) As The Distortion Meter Is Used
Signal Generator ............. Connect to FM Antenna Terminal through the dummy.
(Adjust for the output of the generator to be 60dB at this time.)
VT M isch thszossa fevssedeeetetes Connect to the speaker terminal.
(Adjust for the indication of the VTVM to be 2V with volume.)
Distortion Meter ............... Connect to the speaker terminal.
(Rotate the T101 until the distortion meter is minimum T.H.D.)
DISTORTION METER
98MHz Minimum T.H.D.
SIGNAL
GENERATOR
FMIN SPEAKER OUT
Figure 4. FM IF Adjustment Connection Diagram
2. FM MPX ADJUSTMENT-SEPARATION
STEREO
OSCILLOSCOPE
Pilot Signal Adjust for | Adjustment |
Difference of R
and L must be
maximum.
STEREO
MODULATOR
NOTE : In case of adjusting the stereo
separation, if input is L (or R) channel, R (or L)
channel must be maximum.
Figure 5. FM MPX Adjustment Connection Diagram

3. FM STEREO BEACON SENSITIVITY ADJUSTMENT
STEREO
OSCILLOSCOPE
STEREO
MODULATOR
Figure
6.
FM
Stereo
Beacon
Sensitivity
Adjustment
Connection
Diagram
Pilot
Signal
Adjust
for
Adjustment
Pilot
Display
(on
LCD)
20dB+6dB
VR102

TAPE DECK ADJUSTMENTS
1. AZIMUTH ADJUSTMENT
Deck
Mode
Test
Tape
Test
Point
Adjust
for
Adjustment
Playback
MTT-114
Speaker
out
Head
screw
R/L
Maximum
DUAL-TRACE
SYNCHROSCOPE
ELECTRONIC
VOLTMETER
HEAD PLAYBACK SPEAKER
MODE OUT
TEST TAPE
MTT-114
Figure 7. Azimuth Adjustment Connection Diagram
2. MOTOR SPEED ADJUSTMENT
Deck Mode Test Tape - Adjustment Adjust for
Playback MTT-1114 Speaker out 3kHz + 45Hz
SPEAKER
PLAYBACK
MODE
OUT
FREQUENCY
COUNTER
TEST TAPE
MTT-111
RECORD/PLAYBACK
HEAD
Figure
8.
Motor
Speed
Adjustment
Connection
Diagram

CDP ADJUSTMENTS
1. METER AND JIG FOR ADJUSTMENT
-1. Oscilloscope 1-2. Test disc 1-3. Jitter meter
(Sony type 4 : YEDS-18)
@ @
1-4.
Low
frequency
oscillator
1-5.
Digital
frequency
counter
1-6.
10:1
Oscilloscope
probe
1:1
Oscilloscope
probe
of oh om. o]
1-7. Focus & tracking gain adjustment jig
eo SS Se Se SS SS ee ee
!
J 100K
cj TEO
AF, ree =e
Swi [GND
‘ F 100K =
rae = TEO
GND4 9 C4 FEl
rae
, CN808
t
)
t
0.0018
| oes ae (Mylar) |
\ (1/3) ya
CH2 9 O
lo 1
GND &—# Swe : 22K 10K '
y (1/3) ;
CH1
6
O
0.047
'
o
sei
Mylan
;
i 22K 10K
' 0.039 {
mel ds (Mylar) {
I
'
—10-