Jvc RX 818 VBK Service Manual

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RX-818VBK
RX~880VBK

--Safety Precautions

1.The design of this product contains special hardware and many circuits and components
specially for safety purposes. For continued protection, no changes should be made to the
original design unless authorized in writing by the manufacturer. Replacement parts must
be identical to those used in the original circuits. Services should be performed by
qualified personnel only.

2. Alterations of the design or circuitry of the product should not be made. Any design
alterations of the product should not be made. Any design alterations or additions will
void the manufacturers warranty and will further relieve the manufacture of responsibility
for personal injury or property damage resulting therefrom.

3. Many electrical and mechanical parts in the products have special safety-related
characteristics. These characteristics are often not evident from visual inspection nor can
the protection afforded by them necessarily be obtained by using replacement components
rated for higher voltage, wattage, etc. Replacement parts which have these special safety
characteristics are identified in the Parts List of Service Manual. Electrical components
having such features are identified by shading on the schematics and by (A) on the Parts
List in the Service Manual. The use of a substitute repalcement which does not have the
same safety characteristics as the recommended replacement parts shown in the Parts List of
Service Manual may create shock, fire, or other hazards.

4. The leads in the products are routed and dressed with ties, clamps, tubings, barriers and
the like to be separated from live parts, high temperature parts, moving parts and/or sharp
edges for the prevention of electric shock and fire hazard. When service is required, the
original lead routing and dress should be observed, and it should be confirmed that they
have been returned to normal, after re-assembling.

5. Leakage currnet check (Electrical shock hazard testing)
After re-assembling the product, always perform an isolation check on the exposed metal
parts of the product (antenna terminals, knobs, metal cabinet, screw heads, headphone jack,
contorl shafts, etc.) to be sure the product is safe to operate without danger of electrical
shock.

Do not use a line isolation transformer during this check.

0 Plug the AC line cord directly into the AC outlet. Using a Leakage Current Tester,
measure the leakage current from each exposed metal parts of the cabinet, particularly
any exposed metal part having a return path to the chassis, to a known good earth
ground. Any leakage current must not exceed 0.5mA AC (r.m.s.).

0 Alternate check method
Plug the AC line cord directly into the AC outlet. Use an AC voltmeter having, 1,000
ohms per volt or more sensitivity in the following manner. Connect a 1,5009 10 W
resistor paralleled by a 0.15 11F AC-type capacitor between an exposed metal part and a
known good earth ground.

Measure the AC voltage across the resistor a fififl'fi
With the AC voltmeter. ohms/volts. .. .
Move the resistor connection to each exposed 3 °_ 0" "°'° "5"'V'W-)
metal part, particularly any exposed metal part
having a return path to the chassis, and 0,15; AC Type
meausre the AC voltage across the resistor. r-llr- _
Now, reverse the plug in the AC outlet and Plfgegfi
repeat each measurement. Any voltage -"" >§a¢h exposed
measured must not exceed 0.75VAC (r.m.s.). 1500910, metal Part
This corresponds to 0.5 mA AC (r.m.s.). Good earth ground

--Warning

1. This equipment has been designed and manufactured to meet international safety standards.

2. It is the legal responsibility of the repairer to ensure that these safety standards are
maintained.

3. Repairs must be made in accordance with the relevant safety standards.
4. It is essential that safety critical components are replaced by approved parts.
5. If mains voltage selector is provided, check setting for local voltage.

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RX-BlBVBK
FiX-BBOVBK

I MN172412K8X (IC400)
: SYSTEM CONTROLLER 2

1. Terminal Layout
21 ~ 1

22 84

42 64
43 ~ 63

3. Description

no. Symbol V0 Description :1: Symbol IIO Description
1 - GND 43 OSD SIN I Data for ICZZZ

2 ~ GND 44 OSD ON 0 ON SCREEN on/off

3 -- GND 45 T.CLK I Clock input for IC191
4 - GND 46 IFDATA | Data signalforlC191
5 - GND 47 TADATA | Datasignal for [-��191

6 17G 0 Grid control signal 48 COMSTB | Strobe signal for IC401
7 166 0 Grid controlsignal 49 COMCLK I ClocktoIC401

8 156 0 Grid controlsignal 50 TUNED | TUNEDsignaI to K5104
9 146 0 Grid controlsignal S1 STEREO I STEREOsignaI to IC105
10 136 0 Grid control signal 52 T.MUTE 0 TUNER MUTEsignal output
11 126 0 Grid control signal 53 T.CS l TUNER chip select

12 116 0 Grid control signal 54 CE | Fix the chip enable
13 106 0 Grid control signal 55 - GND

14 96 0 Grid control signal 56 -- GND

15 86 0 Grid control signal 57 - GND

16 7G 0 Grid control signal 58 - GND

17 66 0 Grid control signal 59 - GND

18 SG 0 Grid control signal 60 DIO IIO Datasignalto mm
19 4G 0 Grid control signal 61 DH IIO Data signal to I0401
20 SG 0 Grid control signal 62 DIZ I/O Data signalto ICMH
21 ZG 0 Grid control signal 63 DI3 IIO Data signal to ICADI
22 1G 0 Grid control signal 64 DI4 IIOI Data signal to IC401
23 V" - Power supply 65 REQ 0 Request signalforlc401
24 $1 0 Segment control-signal 66 BUSY o Busysignal from IC401
25 52 0 Segment control signal 67 INI-I I lnhihltsignal input
26 $3 0 Segment control signal 68 RST I Reset signal input

27 S4 0 Segment-control signal 69 X1 - GND

28 $5 0 Segment control signal 70 X2 - Not used

29 56 0 Segment controlsignal 71 V55 - GND

30 S7 0 Segment controlsignal 72 OSC2 - Oscillation terminal
31 $8 0 Segment control signal 73 OSC1 -- Oscillation terminal
32 $9 0 Segment control signal 74 VDD - Powersupply

33 S10 0 Segment controlsignal 75 VL/VH O RY880,RY881 control
34 51 1 0 Segment control signal 76 4/80 SEL I 4/89 select

35 512 0 Segment controlsignal 77 4/89 DETECI' 0 4/80 detect

36 SIEI 0 Segment control signal 78 ~ Notused

37 S14 0 Segment control signal 79 -- GND

38 S15 0 Segment control signal 80 - GND

39 S16 0 Segmentcontrol signal 81 - GND

40 OSD CS 0 Chip selectsignal for IC222 82 - GND

41 SCK O Clock outputforlC222 83 - GND

42 OSD SYNC | VIDEO SYNCH.signa| from IC221 84 - GND

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Page 47

I Power Amplifier section

ENH-287-1

I Idling current

(1) Set the volume control to minimum during this adjustmentSet DAP and surround mode
OFF.And set speaker load selector HIGH.
(2) Turn R791 and R792 fully counterclockwies to warm up befor adjustment.

FlX-81 8VBK
FlX-BBDVB K

If the heatsink is already warm from previous use the correct adjustment can not be made.

(3) Connect a DC voltmeter to R773 resistors leads for left channel, or to R774 for right
channel.

(4) Adjust R773 for left channel, or R774 for right channel, so that the DC
voltmeter becomes 1mV~10mV.

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