The reasons for the failure of the television power beacon are basically the following:
(1) power failure。
This should be a very simple failure, with regular lcd extensions with both electrical and off-site power sources, which are more common outside. In any case, its structure is much simpler than that of the crt monitor, and it is generally vulnerable to small components such as a safety tube, a current bridge, 300v filtering capacity, a power switch, a power management ic, a current output diode, filtering capacity, etc。
(ii) drive plate voltage circuit failure。
Some of the machines are responsible for the internalization of the switch and the output of two sets of power sources, one of which is sv for signal processing, and the other for the provision of high voltage plate backlights for 12v. If the failure of part of the power source is likely to result in the non-output of both sets of power sources, check first if the 12v voltage is normal and then check if the 5v voltage is normal, as the working voltage of the mmu chip of the a/d drive is 5v, so when the failure of the switch is detected, the 5v voltage is measured in 10,000. If no 5v volt pressure or 5v volt pressure becomes low, there may be a problem with the entry level of the power circuit, which means that the 12v conversion to 5v is problematic, and this failure is common, and checking whether the steady pressure is welded or damaged。
Another possibility is that the load of the 5v has increased and the 5v voltage has been reduced to a low level, in other words, that there has been a problem with the rear signal handling circuit, that there has been some damage to the circuit, that there has been an increase in the load, that the 5v voltage has been pulled very low, that there has been a problem with the rear stage, and that after replacing the faulty element, the 5v will return to normal and the failure will normally be resolved。
(3) cmu failure。
There are many reasons for the frequent failure to operate when the 5v voltage has returned to normal, on the one hand because the mcu process is washed away, and on the other hand because the mcu itself is damaged, such as the i/o damage to the mcu mouth, the inability of the mcu to scan the keys, the failure of the mcu, the problem of finding the hardware is useless, even if you have changed the mcu, which is required to program and write, unless it can be purchased to write the mcu, the price is often difficult to accept. In most cases, therefore, general-purpose a/d drives can only be replaced。
Experience with maintenance of long-wind television
Analyzing and overhauling: on-board inspection found no 5v voltage. The 5 volts are controlled by a 4-end pressurer and 5 volts are controlled by 25 feet of power-management chips. The inspection found that 25 feet were not high-altitude, the power-management chip ic701 was properly powered, the crystals were converted, the reposition was clean and the management chip was replaced. Finally, the power source management chip voltage found 17 feet of low voltage, which was the interactive detection input foot, the examination of the communication input and the examination of the circuit (thermal floor end), and the zd121 was found to have leaked and replaced with normal。
