JVC RC-636L User manual

MODEL
RC-636L/LB
FM-SW-MW-LW
4-BAND RADIO
STEREO CASSETTE
RECORDER
No. 1372
July 1978

RC-636L/LB
Contents
Page
SpecihiCations: cose eb Ft OSs seo eee ad See bale Senso e Ae rea sees aaa 2
Main: Parts Mocation sn. see ee Siw ele era aaa bd ia Sa ee Re es I Ds eran dod Oe eo 3
Disassembly & Replacement ... 0.0.0.0 ce ee ee eee eee ee eens 3
Tuner Alignment =: 2. sinccs sete ce gic cde secs sete Rid Gna Reet s! wo HR SSG caval wag Dee aie EN Tele BS eRe ra eae sata Se 45
Adjusting Recording Bias .... 0... 0. ee ee ee eee nee nett ees 8
Adjusting Head Azimuth... as 6 s:scn eae ee le eee Sad Ce ws et eek e Deo the wae MA Pen 8
How to. Fit: Dial Gord: 2.2 foe akc eteee CE oe 0 ee Weare re eb Rew Selo Baad BER ene Wie eneene Conant es 9
Adjustment of Cassette Mechanism .........0 00 eee eee ee ee ee ee eee eee ee ees 10,11
Block: Didgrart:..62si6 ice eden aie iene eS hohe BRA ae ea Se aie al aa ee Be ea ewe Bil te oea oe aaah 12
Wiring Connections 6.o.6c3.6 occ bee ie es ee a id oe DE OE WR a ea ee Hew Ee 13
Schematic Diagram of RC-636L/LB (Tuner) ....... 2-0-0 cece ee ee ee tee eens 14
Schematic Diagram of RC-636L/LB (Amplifier)... 2.0... eee ee eee ees 15
Tuner Circuit Board Ass’y 1.2... 0... ee ee ee ee ee eee eee eee eee ee ees 16,17
Amplifier Circuit Board Ass’y .. 0.0.0... -- cece ee eee ee eee eee eee tee eee ees 18,19
Exploded View of Cassette Mechanism .......-. 20 0c eee eee eee eee ee nee tee ete 20
List of Cassette Mechanism ........ 00. cee eee ee ee ee eee eee eee eee 21
Control Circuit Board Ass’y .. 2.2... eee ee ee ee eee ee ee eee ee eee 22
Power Supply Circuit Board Ass’y (RC-636L) ........ 0. eee ee ee ee ee eee 22
Exploded View of Chassis Ass’y ..........--- seh dole coord sasaice Wein: apa ate an coher eyise sheen ine padre ae a aero 23,24,25
Exploded View of Front Cabinet... 2... 2. ce ec ee ee ete es 26,27
Exploded View of Rear Cabinet (RC-636L) .. 0.2.2... ce eee tet 28
Final Packing Ass’y (RC-G36L) 2.0.0... . ec ee ee eee eee eee 29
Accessories (RC-636L).. 0... ccc ee ee ee ee ere ee ete eee eee eee 29
Difference of Model RC-636LB ........ 0.0... eee ee eee ees 29
Wiring Connection of RC-63GLB (Part) 2.2... 0c. eee ee eee teenies 29
Power Supply Circuit Board Ass’y (RC-G36LB) 2.2... ee ees 30
Exploded View of Rear Cabinet (RC-636LB) ... 20... 00 ccc cece ee ee ee eee eee 30
Final Packing Ass’y (RC-636LB) ... 0.0.0.0... cece ee eee eee eee 31
Accessories (RC-G3GLB) cies sie ae ae ieee eek ee es ER we ee a eee ee See aetna wae aa 31
Specifications
DIMENSIONS: 26.4cm(H) x 47.0cm(W) x 12.3cm(D) WEIGHT: Approx. 6.0kg (with batteries)
10-3/8" x 18-1/2” x 4-7/8" 13.2 Ibs.
Frequency Ranges >: FM 88~108MHz AMPLIFIER SECTION
SW 6~18MHz Speakers 16cm(6-1/2’") x 2,40
MW 540~1600kHz Power Output Max. 9 (4.5 + 4.5) W (DC)
LW 150~350kHz Input Jacks MIC x 2 (0.8mV, low imp.)
Intermediate Frequencies : FM 10.7MHz Output Jacks Ext. Speaker x 2 (402)
SW/MW/LW 455kHz Headphones x 1 (822)
RECORDER SECTION
Tape Speed
Track System
Recording System
Erasing System
S/N Ratio
Fast Forward Time
Rewinding Time
Wow & Flutter
No. 1372
Input/Output Jack
>: DIN
POWER CONSUMPTION :
15W (at RMS power output: 636L
seams Haye) 14W (at 10% THD: 636LB)
4-track 2-channel stereo
re
SEMICONDUCTORS
=
AC
Erasing
Transistors
:
19
More
than
45dB
at
1kHz
Biodas
:
18
Within
90
sec.
(C-60
cassette)
BoweR
SOURCE
Within
90
sec.
(C-60
cassette)
pe
:
12V.8
"R20"
or
“U2”
cells
or
0.14%
(WRMS)
equivalent
AC
110/220/240V,
50/60Hz
Fuse
1AT
ray

RC-636L/LB
Main Parts Location
5G) VY
Fig. 1 Fig. 2
Parts No. Parts Name Description
VXQ4001-001 Knob (Lever) Rec Mute, Mode, Function, Tape
VXS4005-001 (Slide) Volume (L,R), Tone
VXKM520-30011 Fine Tuning
*VXL4021-002 Tuning
*VXQ3007-002 (Lever) STOP/EJECT
*¥X03007-001 ) RECORD
*V¥XQ3007-003 REVIEW, PLAY, CUE, PAUSE
*VJT3019-00A Cassette Door
*VJD3118-002 Head Cover
*VYH1107-001 Chassis
2 Circuit Board Ass’y Tuner
Control
Amplifier
COON OORWNH =
——_- Cassette Mechanism Ass’y
*EAS16P127SC Speaker 16cm(6-1/2"), 42
*VDM5043-002-004 Connector & Wire Ass‘y CN404S for Fine Tuning
*VDM5043-003-001 CN401S for Tuner
*VDM5043-002-002 CN402S for Speakers
Note: 1, Asterisked parts (*) show “NEW PARTS”. Other parts are all “CURRENT PARTS”;
therefore, check your inventory and order situation before placing new order to avoid
making extra stock.
2. The circuit board assemblies and whole assembly of cassette mechanism in this model will
not be available as spare parts.
3. The parts marked /\ are the important parts for safety assurance.
Use the specified part, when replacing the safety assurance part, never use an equivalent
one.
Sa: No. 1372

RC 636L/LB
Disassembly & Replacement
A. Head Cover
Draw the right or left lower ridge of the head cover by a
finger tip.
Note: The head azimuth can be adjusted by removing the
head cover.
Fig. 5
Sn aE eases nn D. Amplifier & Control Circuit Boards
1. Take off the tone and volume control knobs.
Fig. 3 2. Disconnect 2 connectors (B) & (E).
3. Release the wires by straightening the wire clamp (D).
4. Remove 7 screws (11)~(17): SBSB3014Z.
5.
N
B. Rear Cabinet Pull up the circuit board straightly from the cabinet.
1. Remove 7 screws (1)~(3): SDBP3012RS and (4)~(7): ote: 1. Engage the projection of function switch lever
V43899-1. and the slider (F) in place, when mounting the
2.
Disconnect
3
connectors
from
rod
antenna
and
power
circuit
board
on
the
chassis.
supply section. 2. When separating the control circuit board from
the amplifier circuit board, remove 2 screws on
the control circuit board.
Fig. 4
Fig. 6
C. Tuner Circuit Board
1. Set the tuning dial to the minimum frequency.
2. Disconnect 2 connectors from the fine tuning section
(A) and from the amplifier circuit board (B).
3. Remove 3 screws (8)~(10): SBSB3010Z.
4. Draw the circuit board downward with slightly lifting its
lower edge upwards.
Note: Fit the arm of variable capacitor and the dial drum
when mounting the circuit board on the chassis. For
details refer to page 9.
No. 1372 Avaes

RC-636L/LB
E. LED Circuit Board
Press 2 projections of chassis to the arrow direction as
shown in Fig. 7, after removing the tuner circuit board.
Fig. 7
. Fig. 9
F. Chassis Assembly
1. Take off the tone, volume, fine tuning and tuning knobs. :
2. Disconnect the connector (E). H. Power Supply Section
3. Press the STOP/EJECT button to disengaging the Remove 2 screws (30) & (31): SBSB4020C.
internal cassette door opening mechanism.
4. Remove 7 screws (18)~(22): SBSB3014C and (23) &
(24): SBSB3025C.
Fig. 10
1. Parts of Cassette Mechanism
The mechanism of RC-636 is essentially the same as of
RC-525 or RC-323.
Refer to the service manual of RC-525 or RC-323.
Fig. 8
G. Cassette Mechanism Assembly
1. Take the chassis assembly out of the cabinet as following
the previous item F.
2. Remove 5 screws (25)~(29): SBSB3010Z and the screw
(15) as shown in Fig. 6.
_5_ No. 1372

RC-636L/LB |
Tuner Alignment
Output Measuring: Speaker terminal (Impedance =42), output level 5|OmW (0.45V/40}
AM IF & RF Alignment
Input (SSG) Modulation 400Hz, Modulated to 30%
Input Signal Place to be Set the V.
Given to aligned Capacitor to
Repeat the Step 1, and adjust for no further improvement.
Loop Antenna —
105
Frequency
Band
Repeat the Steps 9 & 10.
600kHz rere 600kHz Signal
1400kHz sci paaieatey TC6 1400kHz Signal
Repeat the Steps 12 & 13, and adjust for no further improvement.
[email protected] | __Dummy Antenne TB
Repeat the Steps 15 & 16.
6.0MHz Rod Antenna through 6.0MHz Signal
18.0MHz Dummy Antenna TC3 18.0MHz Signal
Repeat the Steps 18 & 19, and adjust for no further improvement.
FM IF & Discriminator Alignment
1. Connect a sweep generator to the test point TP4.
2. Connect a oscilloscope across the test points TP6 (Hot) and TP9.
3. Align the T3 so that the S-curve will become symmetrical and the noise become minimum.
Note: 1. Align after mounting the tuner circuit board in the cabinet to avoid affection of leakage flux of the speaker.
2. After alignment, demagnetize the coils L10 and T3 by a head demagnetizer to decrease possible modulation hum
due to leakage flux of the speaker.
FM RF Alignment
Input (SSG): Use 75Q terminal, modulation 400Hz modulated to 22.5kHz deviation.
Connect Hot side to TP1 and Cold side to TP2.
Place to be Set the V.
Frequency aligned Capacitor to
109MH2
F
Frequency
M Repeat the Steps 1 & 2.
SOF nal
TP1
&
TP2
9OMHz
ious
106MHz 106MHz Signal
Repeat the Steps 4 & 5, and adjust for no further improvement.

RC-636L/LB
FM MPX Alignment Dummy Antenna
A. Regular Method
1. Connect a frequency counter to the test point TP8
through 50kQ.
2. Ground the test point TP5. o
3. Adjust the variable resistor VR1 so that the frequency R 1 R -, GC |
becomes 19kHz + 100Hz. 1 |
B. Simplified Method
1. Tune to a FM stereo broadcast. ' |
2. Set the variable resistor VR1 to a center position of the —d
range where the stereo indicator keeps lighting. ™m Mi Bie pa ee te Beh A |
R1+R2= 8002
C = 10pF
R1 : Output impedance of S.S.G.
Fig. 11
Parts Arrangement for Alignment
=o No. 1372

RC-636L/LB
Adjusting Recording Bias
Bias Frequency Bias Current
1. Connect a frequency counter across TP201 (Hot) and 1. Connect a V.T.V.M. across TP201 — TP202 and TP301
TP202 (Cold). — TP302.
2. Set the BEAT CUT switch to lower position. 2. Adjust the variable resistor VR203 (L) and VR303 (R)
3. Adjust the oscillator coil L402 so that the counter
indicates 68kHz.
so that the voltage becomes 4.5mV (450uA/10Q).
Fig. 13
Adjusting Head Azimuth
. Connect a V.T.V.M. across the speaker terminal.
. Set the MODE switch to MONO.
. Playback the test cassette for azimuth adjustment.
. Adjust the head angle for maximum output.
Note: The output voltage shows three peaks while
adjusting head angle as illustrated on the right,
adjust for maximum peak.
5. Check that the output difference between MONO and
STEREO is within 3dB.
PWN =
No. 1372
Output
—pe Angie
Fig. 14

RC-636L/LB
How to Fit Dial Cord
1. Dial Cord
Material:
Tetoron
(braided
sheath)
and
Kevlar
(inside
filament),
coated
with
Teflon
Diameter of cord: 0.5mm (20 mil)
Whole length of cord: 1300mm (51-3/16”)
2. Remove the dial scale by loosening 2 screws.
3. Turn the dial drum fully counterclockwise.
4, Fit the cord in numerical order as shown in Fig. 15.
5.
If
the
tuner
circuit
board
has
been
removed
from
the
chassis,
engage
the
projection
of
arm
which
is
mounted
on
the
shaft
of
variable
capacitor
with
the
slot
of
lever
which
is
positioned
opposite
side
of
dial
drum
as
shown
in
Fig.
16.
‘<
a
Fig. 15
Dial Drum
Chassis
“TITTLE
cK tH,
Lever —,_
Arm
Circuit Board i
Variable Capacitor | |
Fig. 16
No. 1372

RC-636L/LB
Adjustment of Cassette Mechanism
Play Timing
1.
2.
No. 1372
In the playback mode, the clearance (A) between the
pinch roller arm and the stopper of head base should be
within 0.2 to 0.3 mm.
If the clearance is beyond the limits, bend the part (B)
of pinch roller arm to adjust the clearance as shown in
Fig. 17.
Pinch Roller Arm
Stopper
(Head Base)
Fig. 17
Check to see that the take-up idler turns at the same
time as the pinch roller or the take-up idler turns first
and then the pinch roller turns, when the PLAY button
is pressed.
a. If the pinch roller turns very later than the take-up
idler, bend the part (C) of head base which is
contacted with the take-up idler by the part (D) to
the (E) direction as shown in Fig. 18.
b. {f the take-up idler turns later than the pinch roller,
bend the part (C) to (F) direction.
Head base
Take-up Idler
Fig. 18
Cue & Review Mechanism
1. Timing of Cue Action
a. In the playback mode, check to see that the take-up
reel disk stops turning after the pinch roller has
stopped turning or stops at the same time and then
the mechanism becomes fast forwarding mode when
the CUE button has been pressed.
b. If the timing is out of order, adjust it as following the
item 2 of “Play Timing”.
2. Timing of Review Action
a. In the playback mode, check to see that the take-up
reel disk stops turning after the pinch roller has
stopped or stops at the same time and then the
mechanism becomes rewinding mode, when the
REVIEW button has been pressed.
b. If the timing is out of order, adjust it as following the
item 2 of “Play Timing”.
Pause Timing
In the playback mode, check that the PAUSE button is
locked and the mechanism temporarily becomes stop mode
when the PAUSE button has been pressed, and that the
button is released and the mechanism becomes playback
mode when the button has been pressed again.
If the mechanism becomes fast forwarding mode, when the
PAUSE button has been gradually pressed, bend the part
(G) of pinch roller arm to the arrow direction to adjust that
the take-up reel and the pinch roller stops at the same time
as shown in Fig. 19.
Pause Bar
Pinch Roller Arm
Fig. 19