1. To check if power is on.

2. To check if the communication line is connected correctly (synchronous screen)

3. In case of synchronous screen, inspect if the green communication lamps of transfer card and receiving card are flashing.

4. If computer display is protected or the display area of display screen is black or purely glue, (synchronous screen)

II. The whole unit does not turn on (blank screen)

1. The horizontal directions of successive few units do not brighten up, please check if the flat cable between the normal unit and failed unit is connected well;
or if Chip 245 works well.

2. The vertical directions of successive few units do not brighten up, please check if power supply is normal.

III. Upper line of unit does not turn on

1. Check if the line pin and 4953 output pin are connected.

2. Check if 138 is normal.

3. Check if 4953 is hot or burnt.

4. Check if 4953 has high level.

5. Check if 138 and 4953 control pins are connected.

IV. The unit does not turn on.

1. Check if 595 is normal.

2. Check if pins corresponding to the upper and lower modules are connected.

3. Check if 595 output pin and module pin are connected.

V. The unit is color defective.

1. Check if 245 R.G data is outputted.

2. Check if normal 595 output pin and abnormal 595 input pin are connected