Why doesn't the top button of the set-top box remote control work?
Analysis and maintenance: The reason why all the buttons of the set-top box remote control do not work is caused by the damage of the crystal oscillator.
If you have dropped the remote control or checked it with the radio, there is no “beep” sound, you can directly replace the new crystal.
After replacing the new crystal oscillator, if the fault cannot be eliminated, the voltage across the crystal of the remote controller should be measured first. When any button is pressed, there will be obvious voltage changes at both ends of the crystal oscillator, indicating that the oscillator can generate a pulse signal. .
The second is to check whether there is a relatively weak voltage change at the output of the remote control signal of the integrated block. If there is any change, check whether the push transistor and the infrared transmitting tube are damaged. Otherwise, most of the integrated blocks are defective.