Produkte Klassifizierung

Empfohlene Produkt

Nachrichten-brief

Abonnieren sie die neuesten angebote Informationen!

Homepage » news

Working principle

The main board of the low voltage DC (usually more than a dozen V, or 5V) by switching chopper into high frequency alternating current, and then through the high-frequency transformer to boost voltage, to achieve the voltage. High voltage board power supply and signal from the motherboard, there are so many wires and the main board connected: power supply V+, power supply G, switch signal S, brightness signal F (some not).

application

All rely on CCFL light emitting devices, such as industrial control LCD display, flat light display, Portable LCD terminal POS, mobile DVD, digital photo frame, ultra Book advertising box, display cabinets, industrial control equipment, etc.

The function of high pressure strip

The role of the high voltage bar is to produce high voltage (generally more than 1 thousand V) light CCFL lamp, and provide stable AC current (2-8mA) to maintain the normal operation of the lamp tube.

Common fault editor

Immediately after the screen lit

The problem is mainly for the high pressure feedback circuit plays the role of lead, such as: high voltage feedback circuit protection, lead to problems resulting in no feedback voltage, the feedback current is too large, loose tube PIN and IC output is too high will lead to the problem, in principle, as long as the IC output, self-excited oscillation is normal, any other part the bad will lead to the problem, the phenomenon is the liquid crystal display board boost the most common adverse phenomenon.

Maintenance is the main method of:

(1) short connection: under normal circumstances, there is a IC PWM control or force output, short circuit to ground the foot it will not be affected by the feedback circuit, force output pulse wave, the boost plate are generally light, and circuit testing, but must pay attention: so when specific the fault point has not been found, so short too long may cause some abnormal to the phenomenon, such as: poor contact line, forced output may cause ignition and burn in line!

(2) contrast test method for liquid crystal display tubes were used for more than 2, most of the manufacturers in the design around the lamp adopts dual output, namely the two tube corresponding to the two circuit, the same time, the two circuit can use contrast test method to determine the fault point! Of course, a road lamp control two with some machine, this method is invalid!

On the other hand, in the case of unknown, it is best not to short circuit IC each foot, otherwise there may be an unintended consequences!

Light but no display

This problem is mainly boost board line does not produce hypertension causes, such as: 12V did not join or the voltage is not normal, the control voltage without grounding is not normal, no IC / no oscillation output, a self-excited oscillation circuit are adverse this phenomenon!

Three

If l plate is causing the problem, most of them are boosting board short lead, usually easy to detect, such as 12V, IC, self-excited tube breakdown breakdown will lead, in addition: power lines on the same plate part or boost a plate (i.e. together) machine, power no output or not will have a normal maintenance can be cut off, which is part of the power supply voltage, the problem of confirmation.

Brightness bias

The brightness control circuit is not normal, the 12V is low, the IC output is low, the high voltage circuit is not normal and so on will cause this problem, the part may be accompanied by heating for several tens of seconds to protect, produce no show!

Power indicator light flashing

The problem with three phenomenon almost, the majority of the pipe leads to the breakdown!

interfere

The main water ripple interference and jitter jitter, flicker star / screen (the phenomenon of minority, most are the LCD screen, the main problem) is the high-voltage line problem.

Development situation editor

The backlight is mainly used in the LCD driver, LCD backlight mode in large size, is still dominant, but in recent years due to the introduction of the LED backlight, CCFL backlight has gradually disappeared in the traditional small size display market, along with the rapid development of LED backlight, a few years later, we have the pressure for having heard it many times "will gradually quit the stage of history.

Replace edit

Repair LCD high-pressure fault is a headache, especially difficult fault or with less than the corresponding pressure when the first two big, but not as scrap or retreat, that no face, in fact, people are living, as long as any pressure hold, then it is "universal". Do not know the parameters to buy pressure, see there are so many interface pressure lines, dizziness!

In fact, very simple, first of all to determine the power line of the positive and negative, there is generally a fuse is a positive pole, negative pole is connected to the negative electrode.

Then the best way to determine the voltage, voltage is determined to see if the capacitance of the mark, it is about 6V 3.3V, if the capacitor superscript around 12V, so the input voltage is 5V, if it is 24V or above, there is a 12V, and so on, the standard capacitor volt number by two, the closest a few volts is a few volts.

Some people say then according to this, it still doesn't work, or just flashed out, is a lot of pressure is more than this, how does that do? Find out the control at the foot, foot is receiving a small transistor on the general is directly connected to a transistor. Up to the middle of a small capacitor should be easy to recognize, control foot is generally 3.3V and 5V, there are also individual is grounded, so we do not know the circumstances, try not to the ground, then followed by 3.3V 5V, if the input voltage and the control voltage is more than 3.3V is can be directly combined. The extra feet make him empty.

CCFL Inverter