China JYM-560 Schematic

SERVICE MANUAL

*** CONTENTS ***

1.Safety Instructions

2. General Alignment

3. IC BLOCK DIAGRAM

4. TROUBLE SHOOTING

5. BLOCK DIAGRAM

6. CIRCUIT DIAGRAM

* * * WARNING * * *

In order to prevent electric shock, do not remove cover. No user-serviceable parts inside, Refer servicing to qualified service personal.

1. SAFETY INSTRUCTIONS

PRECAUTIONS DURING SERVICING

1. In addition to safety, other parts and assemblies are specified for conformance with such

regulations as those applying to spurious radiation. These must also be replaced only with specified replacements. Examples : RF converters, tuner units, antenna selection switches, RF cables, noise-blocking capacitors, noise-blocking filters, etc.

2. Use specified internal Wiring. Note especially:

1) Wires covered with PVC tubing

2) Double insulated wires

3) High voltage leags

3. Use specified insulating materials for hazardous live parts. Note especially:

1) Insulation Tape

2) PVC tubing

3) Spacers (Insulation barriers)

4) Insulation sheets for transistors

5) Plastic screws for fixing micro switches

4. When replacing AC primary side components (transformers, power cords, noise blocking

capacitors etc), wrap ends of wires securely about the terminals before soldering.

5. Make sure that wires do not contact heat-generating parts (heat sinks, oxide metal film resistors,

fusible resistors, etc.)

6. Check if replaced wires do not contact sharply edged or pointed parts.

7. Make sure that foreign objects (screws, solder droplets, etc.) do not remain inside the set.

MAKE YOUR CONTRIBUTION T O PROTECT THE ENVIR ONMENT Used batteries with the ISO symbol for recycling as well as small accumulators (rechargeable

batteries), mini-batteries (cells) and starter batteries should not be thrown into garbage can. Please leave them at an appropriate depot.

WARNING

Before servicing this TV receiver, read the X-RAY RADIATION PRECAUTION, SAFETY

INSTRUTION and PRODUCT SAFETY NOTICE.

X-RAY RADIATION PRECAUTION

1. Excessively high voltage can produce potentially hazardous X-RAY RADIATION. To avoid

such hazards, the high voltage must not exceed the specified limit. The normal value of the high voltage of this TV receiver is The hi

gh voltage must not exceed 29 kV under an circumstances : Each time when a receiver require servicing, the high voltage should be checked. The reading of the high voltage is recommended to be recorded as a part of the service record. It is important to use an accurate and reliable high voltage meter.

2. The only source of X-RAY RADIATION in this TV receiver is the picture tube. For continued

X-RAY RADIATION protection, the replacement tube must be exactly the same type as specified in the parts list.

3. Some parts in this TV receiver have special safety related characteristics for X-RAY

RADIATION protection. For continued safety, the parts replacement should be under taken only after referring the PRODUCUT SAFETY NOTICE.

26 kV at ze

ro beam current (minimum brightness).

SAFETY INSTRUCTIONS

The service should not be attempted by anyone unfamiliar with the necessary instructions on this TV receiver. The following are the necessary instructions to be observed before servicing.

1. An isolation transformer should be connected in the power line between the receiver and the AC

line when a service is performed on the primary of the converter tran sformer of the set.

2. Comply with all caution and safety related provided on the back of the cabinet, inside the

cabinet, on the chassis or picture tube.

3. To avoid a shock hazard, always discharge the picture tube’s anode to the chassis ground before

removing the anode cap.

4. Completely discharge the high potential voltage of the picture tube before handling. The picture

tube is a vacuum and if broken, the glass will explode.

5. When replacing a MAIN PCB in the cabinet, always be certain that all protective are installed

properly such as control knobs, adjustment covers or shields, barriers isolation resistor networks etc.

6. When servicing is required, observe the original lead dressing. Extra precautio n should be given

to assure correct lead dressing in the high voltage area.

7. Keep wires away from high voltage or high temperature components.

8. Before returning the set to the customer, always perform an AC leakage current check on the

exposed metallic parts of the cabinet, such as antennas, terminals, screw heads, metal overlays, control shafts etc., to be sure the set is safe to operate without danger of electrical shock. Plug the AC line cord directly to the AC outlet (do not use a line isolation transformer during this check). Use an AC voltmeter having 5k ohms per volt sensitivity or more in the following manner. Connect a 1.5k ohm 10 watt resistor paralleled by a 0.15uF AC type capacitor, between a good earth ground (water pipe, conductor etc.) and the exposed metallic parts, one at a time. Measure the AC voltage across the combination of 1.5k ohms resistor and 0.15uF capacitor. Reverse the AC plug at the AC outlet and repeat AC voltage measurements for each exposed metallic part. The measured Voltage must not exceed 0.3V RMS. This corresponds to 0.5mA AC. Any value exceeding this limit constitutes a potential shock hazard and must be corrected immediately.

The resistance measurement should be done between accessible exposed metal parts and power cord plug prongs with the power switch “ON”. The resistance should be more than 6M ohms.

PROODUCT SAFETY NOTICE

Many electrical and mechanical parts in this TV receiver have special safety-related

characteristics. These characteristics are often passed unnoticed by a visual inspection and th e protection afforded by them cannot necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Replacement part which have these special safety characteristics are identified in this manual and its.

Supplements : Electrical components having such features are identified by shading on the

schematic diagram and the part 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 same safety characteristics as specified in the parts list may create shock, fire or other hazards.

2. GENERAL ALIGNMENT

 CPT MAGNET ADJUSTMENT

CONVERGENCE MAGNET ASSEMBLY POSITIONING

Convergence magnet assembly and rubber wedges need m echani cal posi t i oni n g follo wi n g fig ure 1.

FIG 1 Rubber Wedges Location

COLOR-PURITY-ADJUSTMENT

NOTE : Before attempting any purity adjustments, the receiver should be operated for at least 15

minutes.

1. Demagnetize the picture tube and cabinet using a degaussing coil.

2. Turn the CONTRAST and BRIGHTNESS controls to maximum.

3. Adjust RED and BLUE Bias controls to provide only a green rather.

4. Loosen the clamp screw holding the yoke, and slide the yoke backward to provide vertical green belt(zone) in the picture screen.

5. Remote the Rubber Wedges.

6. Rotate and spread the tabs of the purity magnet(See figure 2) around the neck of the picture tube until the green belt is in the center of the screen. At the same time, center the raster vertically.

7. Move, the yoke slowly forward until a uniform green screen is obtained. Tighten the clamp screw of the yoke temporarily.

8. Check the purity of the red and blue raster by adjusting the BIAS controls.

9. Obtain a white raster, referring to "CTR GRAY SCAL ADJUSTMENT".

10. Proceed with convergence adjustment

FIG 2

CONVERGENCE ADJUSTMENTS

NOTE : Before attempting any convergence adjustments, the receiver should be operate for at least

15 minutes.

CENTER CONVERGENCE ADJUSTMENT

1. Receiver crosshatch pattern with a color bar signal generator.

2. Adjust the BRIGHTNESS and CONTRAST Controls for well defined pattern.

3. Adjust two tabs of the 4-Pole Magnets to change the angle between them (See figure 3) and superimpose red and blue vertical lines in the center area of the picture screen.

4. Turn both tabs at the same time keep in their angles constant to superimpose red and blue horizontal lines at the center of the screen. (See figure 4.)

5. Adjust two tabs of 6-Pole Magnets to superimpose red/blue line with green one. Adjusting the angle affects the vertical lines and rotating both magnets affects the horizontal lines

6. Repeat adjustment 3, 4, 5 Keeping in mind red, green and blue moment, because 4-Pole Magnets and 6-Pole Magnets interact and make dot movement complex.

FIG 3 FIG 4

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