JVC AV-32 Service Manual

ENG-02030503-T

JVC Power Supply trouble shooting procedure

This procedure is based on GF Chassis. Minor differences could be seen in other chassis

Important Service manual information

Due to component tolerance production changes were made during manufacturing. Every effort is made to inform those changes in the service manual. During troubleshooting, Always refer to the service manual Listed below are explanations of some of the abbreviations used in JVC service manual

1. (*): Refer to the NOTE

2. (BW): Bus wire is used instead of that particular component

3. (OPT): The specific component is optional and is not used in this model

4. (Y): Chassis configuration bus wire

5. Shaded: Safety related components. Do not substitute these components

Chassis Preparation

1. Remove the main PWB along with the Operation PWB from the television

2. Do not apply AC power to the PWB

3. Using a suitable resistor, discharge the electrolytic caps, C910 and C538

4. Visually inspect the PWB and replace if there are any burnt components

5. Connect a jumper wire between D922 Cathode and IC901 pin 4

6. Connect another jumper wire between the chassis’

cold ground (ex: E1) and hot ground (ex: IC901 heat sink)

7. In order to disconnect 130V supply from the flyback transformer, remove L921.

Test Jig Preparation

Connect two long jumper wires from a 120V lamp assembly as shown in figure Use a 40W lamp.

Test Instruments

1. Variable DC Power Supply (0~30V; 3A)

2. Digital Multimeter

3. Alligator clips

4. Test jig as shown in picture

Caution

Before replacing any components, turn off or disconnect all power supplies and discharge any charged caps

Test Jig

Overall

Start

Follow procedures listed in page 1 and prepare the chassis for troubleshooting

Using the external power supply, connect 7.0V DC

between D922 Cathode and the chassis' ground

Observe the Current readings on the power supply's current meter

Trouble shoot, and if

defective, replace CPU

or 5V regulator

components

On the external power supply, increase the DC voltage from 7.0V DC to

Press the Power On/Off button and confirm the Power indicator operation

During Power On/Off operation, measure DC voltage on IC901(STR-F6626) Pin1

Less than

Measure DC on IC701 (CPU) Pin61 and Pin22

5 ~ 5.5V DC

Power Off: not lit

Power On:lit

Power Off: approx

Power On:

1.0A

Yes

2.5V

Trouble shoot and replace

any shorted components

13.0V DC

Goto Page 3 (CPU basic)

Goto Page 4 (Feedback)

Refer to the Schematic. At Q923 collector or a convinient location, measure 13V

Power Off:0V

Power On: 13V

Yes

Refer to the schematic. Measure the collector of both relay driver transistors (Q921 and Q922)

Power Off: 13V

Power On: 0V

Yes

Goto Page 7, Page 8

Goto Page 5 (SW 13)

Goto Page 6 (Relay control)

GF chassis Power Supply troubleshooting procedure Page: 2

Start

Goto Page 2

Follow procedures listed in

for troubleshooting and

page 1.

Prepare the chassis

Confirm CPU Vcc.

CPU basic

(Before this test, Start with Page 2)

Using the external power supply, connect

between D922 Cathode and the chassis' ground

Press the Power On/Off button and confirm the Power indicator

operation

Power Off:

Power On:

CPU pin7:

Power Off: Power On:

CPU pin54:

>4.5V

Yes

not lit

lit

5V 0V

13.0V DC

Yes

couple of seconds

Goto Page 2 (Overall)

Trouble shoot power

Yes

If IC703 pin2 is

5V, Replace

IC703 (RST)

indicator LED or

related components

Measure IC703

(reset IC) pin1

Flashes after

Troubleshoot if

there is >0V on

CPU pin 14

Yes

IC701 (CPU)

> 4.0V

Yes

Replace

CPU pin 62, 63

5.0V 12MHz Oscillation

Yes

CPU pin 4, 5

5.0V

Yes

Trouble shoot power indicator LED or related

components

Replace CF701,

C718, and C717.

Measure Pin 62

Replace if any

components on

Pin4 and Pin5 and

check again

Yes

shorted

5.0V 12MHz

Yes

5.0V

Goto Page2

GF chassis Power Supply troubleshooting procedure Page: 3

+ 6 hidden pages