Universal Remote control ( 4 in 1 )

Fault 1: all the buttons on the remote control don't work.

Analysis and maintenance: most of the reasons why all the keys of the remote controller don't work are caused by the damage of the crystal oscillator. If you have fallen or checked with the radio that there is no "beep" sound, you can directly replace it with a new crystal oscillator. After the replacement of a new crystal oscillator, if the fault still cannot be eliminated, the voltage at both ends of the crystal oscillator should be measured first. When any key is pressed, there will be obvious voltage change at both ends of the crystal oscillator, which indicates that the oscillator can produce pulse signal. The second is to check whether there is a relatively weak voltage change at the remote control signal output end of the integrated block. If there is a change, check whether the driving triode and the infrared transmitting tube are damaged. Otherwise, most of the integrated blocks are defective.

Fault 2: some buttons don't work.

Analysis and maintenance: this phenomenon shows that the remote control is normal as a whole, and the reason why some keys don't work is that the contact of the key circuit can't conduct effectively. Most of the contacts on the circuit board in the remote control are contaminated, which makes the contact resistance increase or cannot be connected. Cotton dipped in absolute alcohol can be used to wipe the carbon film contacts, but not too hard to prevent the carbon film from wearing or falling off. Aging or wear of conductive rubber can also cause individual bonds not to work. At this time, as long as the conductive rubber contact point pasted in the cigarette box tin (preferably aluminum foil adhesive) try. If the above methods can not make the remote controller return to normal operation, check whether there is crack or poor contact in the circuit from the keying signal input and output end to the contact point of the integrated block, especially at the connection between the carbon film contact and the circuit line. If necessary, replace the integrated block.