Lcd tv panels, complex circuits, high voltage, large currents, large spare parts, multiple failures and maintenance difficulties, and understanding of the workflow and rationale of circuit boards are necessary for repair. Here's a map of the circuits on the television panels:
To clear the course of the circuits and simplify the chaotic circuits, we split them into five sections, and the following is a chart of their structure, which clearly shows how the circuits interact:
When the engine is on, the flow filtering circuit works, producing 300v voltage. Electrifying pfc circuits, after which pfc works, output of 400v volts to power the main secondary circuits, 24v volts to back-stage circuits after the main circuit transforms frequency currents, 12v volts to the main panel after the secondary circuit works, and vcc voltage to open on-board circuits. On the main plate, 12v voltage relief to cpu 5v. (different power panels, some, main circuit output 24v, 12v, 5v, secondary circuit output 5v depending on the manufacturer's design). Here's a map of the power panel:
When using the remote control key, switch-off circuits give the main circuit a low level of electricity, one high level of electricity to q12 via the reverse q4, which directs the light to the two feet of the main circuit chip, the chip ceases to work, the main circuit does not work and the pfc chip ceases to work, and the pfc circuit ceases to work, so on-calls only filter the current and secondary circuits, while the other circuits do not work。
This is a filter current circuit, which provides 300v voltage mainly to the back circuits. If the engine is turned off and the light is not on, the safety tube, pressure-sensitive electrical resistance, and whether the current bridge is damaged or, if there is a 300v output, the rear。
It has a secondary power circuit, which, after entering 300v voltage, produces 12v voltage to the main panel and vcc voltage to open the stand-by circuit. If the light is not on and the current circuit has a 300v voltage output, check if there is a 12v and vcc output and if not, check the switch and power chip。
If the sub-power is normal, the signal light is on, and the main power source is not 24v out, the switch circuit is checked, the main plate is not sent with 5v voltage, the main plate is damaged, and there is a check here, primarily the q4, q12 and the photocolumn。
The main circuit is inspected if the main plate delivers high-altitude circuits and the waiting circuit is normal without 24v voltage output。
Check its chips, switches and other circuits, check if the 24v voltage is unstable, check if there is a 400v voltage input, and check the pfc circuit if only about 300v。
First, check for vcc voltage input on foot 1 of the pfc power chip and, if not, check for vcc output from the main power source. If, for example, check for chips, switches, etc., there is also a default voltage protection circuit on the stand-by circuit, which, if it has problems, can also result in pfc circuit output below 300v。
