If you listen to your DP-666 radio several times with headphones and then unplug the headphones, the speaker will stop producing any sound.
First of all, we are very sorry that this happened. Our initial judgment is:
This problem is caused by poor contact of the pin spring inside the 3.5mm headphone jack of the DP-666 radio.
DP-666 uses the metal dome inside the headphone jack to control the opening and closing of the speaker.
The model of the headphone jack is PJ-3270, and its working principle is shown in the figure below:
When headphones are plugged in, PIN6 and PIN2 are disconnected, EN_MAX97220 is high level, and the headphone amplifier is turned on; #SHUTDOWN_SPK is low level, the speaker amplifier is turned off; the radio sounds through the headphones.
When headphones are unplugged, PIN6 and PIN2 are connected, EN_MAX97220 is low level, the headphone amplifier is turned off; #SHUTDOWN_SPK is high level, the speaker amplifier is turned on; the radio sounds through the speaker.
Everything should be fine, but we found that PIN6 and PIN2 of some batches of PJ-3270 had poor contact. When the headphones were unplugged, PIN6 and PIN2 were always disconnected, causing the speaker amplifier to be unable to turn on and the speaker to make no sound.
The physical pictures of PIN6 and PIN2 are as follows:
When headphones are plugged in, PIN6 and PIN2 are disconnected.
When headphones are unplugged, PIN6 and PIN2 are connected.
Solution:
Therefore, if your DP-666 has a problem with the speaker not making any sound, we recommend that you open the case and polish the PIN6 and PIN2 of the headphone jack to ensure that PIN6 and PIN2 are connected when the headphones are unplugged.