Jvc RX 774 VBK Service Manual

Page 2

http : //getMANUAL . com

RX-774PBKlRX-774PGDIRX-774VBK 3

-Safety Precautions

1.This 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 (Al) on the Parts List in the Service Manual. The use of a
substitute replacement 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, control

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.

. 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 areturn path to the chassis, to a known good earth ground. Any leakage
current must not exceed 0.5mA AC (r.m.s.)

. 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 9

mannetf Connect a 1,500 10W resistor paralleled Ac VOLTMETER

by a 0.15 F AC-type capacitor between an exposed EB (Having 1000

metal part and a known good eanh ground. Oth/VOHSY ..
Measure the AC voltage across the resistor with the ° "0? sensmvrty)
AC voltmeter.

Move the resistor connection to eachexposed metal (1151: AC TYPE

part, particularly any exposed metal part having a ---1|~-- place this
return path to the chassis, and meausre the AC probe on
voltage across the resistor. Now, reverse the plug in 1 0 0M1 0W ' each exposed
the AC outlet and repeat each measurement. voltage 5 9 mm?" Dam

measured Any must not exceed 0.75 V 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.

A CAUTION Burrs formed during molding may be left over on some parts of the chassis. Therefore,
pay attention to such burrs in the case of preforming repair of this system.

Page 42

RX-774 P/RX-774V

2-2

I MN172412JABZ (IC400) : FL Tube Drive Control Micon
1 . Terminal Layout

ii: Symbol Functions if: Symbol Functions

1 S22 Segment controlsignal output 43 JOG4 Connect to volume

2 321 Segment controlsignal output 44 MBUSY Busy signal to IC401

3 $20 Segment controlsignal output 45 MCLK Clock signal to lC401

4 s19 Segment controlsignal output 46 COMMAND Command final to lC401

5 s13 Segment controlsignal output 47 STATUS Statusiignal tot IC 401

6 s17 Segment controlsignal output 43 M/CS Control signal to lC401

7 s15 Segment controlsignal output 49 RM Remoconsignal terminal

8 S15 Segment controlsignal output 50 VCRI Compulink signal input

9 S14 Segment controlsignal output 51 DCSI Compulink signal input
10 S13 Segment controlsignal output 52 DCSO Compulink signal output
1 1 s12 Segment controlsignal output 53 VCFtO Compulink signal output
12 51 1 Segment controlsignal output 54 TVO Compulink output
13 $10 Segment controlsignal output 55 TVC Compulink control output
14 39 Segment controlsignal output 56 JOGS Connect to mullti jog
15 88 Segment controlsignal output 57 JOGs Connect to mullti jog
16 37 Segment controlsignal output 58 POWER From @wer supply
17 SS Segment controlsignal output 59 STANDBY Standby signal terminal
18 35 Segment controlsignal output 60 K|3 Key matrix input
1g 34 Segment controlsignal output 51 KI2 Key matrix input
20 S3 Segment controlsignal output 62 KI1 Key matrix input
21 32 Segment controlsignal output 63 Klo Key matrix input
22 51 Segment controlsignal output 64 SS6 Segment controlsignal output
23 VPP Powe supply tot FL display 65 535 Segment controlsignal output
24 G14 Grid control signal output 66 $34 Segment controlsignal output
25 G13 Grid controlsignal output 57 $33 Segment controlsignal output
26 G12 Grid controlsignal output 68 RST Reset signal input
27 G11 Grid controlsignal output 69 X1 Connect to ground
28 G10 Grid controlsignal output 70 X2 No use
29 (39 Grid controlsignal output 71 V88 Connect to ground
30 G8 Grid controlsignal output 72 OSCZ Oscillation terminal
31 G7 Grid controlsignal output 73 0801 Osillation terminal
32 G6 Grid controlsignal output 4 VDD Power supply
33 (55 Grid controlsignal output 75 $32 Segment controlsignal output
34 G4 Grid controlsignal output 76 831 Segment controlsignal output
35 (53 Grid controlsignal output 77 530 Segment controlsignal Output
36 G2 Grid controlsignal output 78 529 Segment controlsignal output
37 Connect to 0408 79 828 Segment controlsignalogutput
33 Connect to 0407 so 827 Segment controlsignal output
39 G1 Grid controlsignal output 81 $26 Segment controlsignal output
40 JOG1 Connect to source selector 82 825 Segment controlsignal output

31 JOG2 Connect to source selector 83 $24 Segment controlsignal output
:12 JOGS Connect to volume 84 $23 Segment controlsignal output

Page 47

RX-774 P/RX-774V

3.Functions
R}? Symbol l/O Function
1 YIN I Lux signal Input termianl for Superinpause indocation
2 CIN I Contrast signal input terminal for Superinpause indication
3 VIN I Composit video signal input terminal for Superinpause indication
4 AVcc - Analog power supply terminal
5 F800 0 Internal collar barst phase indication signal
6 m 0 Verticak blanking signal output terminal
7 Vcc . Power supply terminal
8 EXS I Clock generater outside circuit terminal for collar barst
9 XS 0
10 WC 0 Horizontal signal output terminal
11 MC 0 Vertical signal output terminal
12 fiH-SYN | EXT horizontal signal input terminal
13 MN | EXT vertical signal input terminal
14 V35 . GND
15 EXD | Dot clock generater outside circuit signal terminal for indication
16 XD 0
17 V08 0 Character & background signal output terminal
13 V002 o Collar signal output terminal
19 VOC1
20 VOCO
21 fiT l Test signal input terminal
22 SCLK I Shift clock input terminal tor serial transmission
23 SIN I Serial data input terminal
24 Es | Tip select terminal
25 VOUT O Composit video signal output terminal
26 COUT 0 Contrast signal output terminal
27 VOUT O Lux signal output terminal
28 AVss _ Anarog GND terminal

2-7