LCD display Inverter lamp has a direct relationship Inverter typical failure of performance: The LED light is able to control, the host indicator does not light or a light is off. Therefore, it may be Inverter failure, may also be damage to the lamp. According to overhaul the easier issues first principles, should first check the lamp.
†(1) The lamp examination
To use their own separate voltage driver board, each lamp test again, two lines of a light, two lights and four-wire, four-lamp eight lines just take one of the two can be tested. For the six-lane of the four-lamp lamp, take two thick lines of the same color connect can be tested. The particular lamp does not light, the lamp can be determined.
(2) Inverter check
LCD monitor Inverter has two forms: one is a single board structure; another one with the power structure. When the Inverter fails, take a different approach to maintenance.
For veneer Inverter, can be directly replace the entire board, is relatively simple.
One of the one with the power board, you should first check the Inverter power supply fuse, and then check the oscillation transistor, diode, one by one detection method will find the faulty components, replace it. For integrated Inverter maintenance is very difficult, only
Using a separate Inverter substitution. The tube has been damaged. Inverter common troubleshooting.
Inverter common faults and repair methods are as follows:
1) screen instant light immediately after black
Screen instantly lights up immediately after the black failure is mainly caused by poor Inverter feedback circuit. If the voltage is too high lead to protection, the feedback circuit fails, the occur without feedback voltage, feedback current is too large, lamp PIN loose, IC output is too high and other symptoms.
The repair methods There are two:
(1) short connection
General liquid crystal display, pulse width modulation IC pin control or force the output, the pin is shorted to ground its unaffected by the feedback circuit, forced output pulse, both general light boost board, and circuit testing, to find out the point of failure. Note, however, the shorted time can not be too long, otherwise they will be high voltage line is bad, forced output, which led to the ignition or burn Inverter.
(2) comparison test method
LCD monitor left and right lamp with dual output, that is the two lamp corresponding to the same two control circuit that can be used multimeter two circuit testing, and the test results of the two circuits compared, it can be determined whether there is malfunction. But there are also display all the way to control two lamps, you can not use this method.
2) After the power lights but no display
After power lights but no display generally boost board circuit does not generate high pressure caused. Fault There are several reasons:
① 12V to join or the 12V voltage is not normal;
(2) control voltage not joined;
The ③ ground is not normal;
The ④ IC poor, without oscillation, no output;
(5) self-oscillating circuit is faulty.
Should detect whether the step-up board short-circuit fault; detection 12V-to-ground, self-excited tube is breakdown, Ic breakdown. Models for the power section with step-up board lines connected together, no display problems also occur when no power output or abnormal. Maintenance, can be cut to boost part of the power supply circuit, determine the fault lies in the power supply section or in the part of the step-up board to narrow the fault.
3) dim brightness
The dim brightness Failure are the following:
① boost the brightness control circuit board is faulty;
2 12V voltage output is low;
(3) IC output is low;
④ high voltage circuit is not normal.
4) Power light is flashing
Power light blinks and no light, almost no reasons for the failure, the tube is due to the breakdown. In accordance with dull, silent, Figure fault detection and maintenance.
5) graphic display, the screen is dim, red, purple, but the brightness can be adjusted. Do not blink.
Such cases are usually backlight lamp aging, this situation is usually not sudden, usually due to the accumulation of solution only replace the lamp.
6) graphic display screen flicker, no redness, purple screen issue "creak" sound
Such tubes are generally good, because a high-voltage components after working a long Inverter poor contact (usually chip inductors) caused.
7) The screen does not light, but can vaguely see the graphic display
When such a failure occurs bootable listen, if you can hear a "creak" sound, you can determine the lamp power supply circuit or damage to the lamp, you can check the power socket of the lamp; if not open circuit, only to be replaced lamp; if you do not hear a "creak" sound, it may be open or damaged parts on the Inverter is usually a problem with the power supply cable or signal lines, only by means of a multimeter measurement method using a stepwise strategy judgment. the location of the fault.
The Inverter the substitution method
LCD display Inverter is the most common single lamp, dual-lamp, four lights and six lights and wide mouth (mouth) with narrow mouth (mouth) of the points. Inverter operates at high voltage, high current state, the part is easy to aging (in particular the high voltage coil).
1) substitution principle
Inverter substitution Universal Inverter LCD lamp number and size of the interface options, such as four-lamp small mouth LCD screen on the selection of the four light small mouth Inverter. Inverter working conditions, just to find the fault plane 12V, ground and switch control signal 3
Line, and then received a new Inverter can be. 12V power and ground are easy to find, hard to find the switch signal line. Switching signal from the driver board, can be repeatedly press the key to open the panel, measured with a multimeter which wires OV 5V changes, which line is the switching signal line.
Brightness control generally can not receive, the lamp light failure will be excluded.
2) Power the substitution of high-pressure combo plate
The high-pressure part of the power supply high-pressure combo plate damage for the entire board, although convenient, but not economic, and the volume for the one board is not readily available. The following methods can be used: circuit analysis, the original high-pressure part of the device removed and leave space in the original board paste an Inverter be found on the original circuit Inverter required three working conditions, corresponding access to the new Inverter and good insulation protection, the lamp will be lit.
3) Inverter substitution Notes
Inverter substitution should pay attention to the following points.
The ① working voltage to be consistent. The type of liquid crystal display Inverter power supply voltage is not the same. For example, the same dual-lamp Inverter, there are 12V, 14V power supply method, substitution, you should select the input voltage of the Inverter.
(2) backlight number of interfaces and interface style to be consistent. For example, for four-lamp Inverter, try to choose the four-lamp Inverter for substitution, except in special cases, generally do not use the dual-lamp Inverter by changing the output method substitution.
The ③ drive power to match. The power to be the same or higher than the original machine, if the new Inverter power will lead to increased output tube heat, shortened life, or simply can not light the lamp.
(4) installation to the right size. In particular, the volume is not too large, otherwise difficult to assemble.
(5) in installing the Inverter
, to ensure that the isolation of the high-pressure part of the display of metallic materials to maintain a distance of at least 4mm, or use of a sufficient level (3kV) insulating material, to avoid high-pressure discharge. In order to avoid interference, must take Inverter edge matching holes screwed to monitor metal shell, inconvenience fixed, but also with thick wire connection.