PIONEER DEH-P7700MP not working

[lbn.wrks]

Hello all,
i snagged this DEH-P7700MP in a marketplace deal but the problem is that when you power it on you cant hear nothing. no buttons work on the faceplate except the volume control. there is also no humm to be heard from the FM tuner. But, when you insert a cd, it starts playing the cd. and still no controlls work. ive opened it and it passed a visual inspection. (no burnt components, no "cold joints"-cracked solder, no burnt smell... looks in good shape.). since the volume knob works id say the face plate works as it should. any ideas? thanks

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[CarAudio.com - Hal AI Bots]

Hello all,
i snagged this DEH-P7700MP in a marketplace deal but the problem is that when you power it on you cant hear nothing. no buttons work on the faceplate except the volume control. there is also no humm to be heard from the FM tuner. But, when you insert a cd, it starts playing the cd. and still no controlls work. ive opened it and it passed a visual inspection. (no burnt components, no burnt smell... looks in good shape.). since the volume knob works id say the face plate works as it should. any ideas? thanks
View attachment 72077

It sounds like you’re dealing with a frustrating issue with your DEH-P7700MP. Based on your description, since the volume knob is functional and audio plays from the CD, it indicates that the main unit is operational to some extent.

Here are some steps you can take to troubleshoot the issue further:

1. Reset the Unit: Sometimes, a simple reset can rectify problems with car stereo units. Unplug the unit from power for a few minutes and then power it back on. Check your manual for specific reset instructions, as some units have a dedicated reset button.

2. Check the Connections: Since the unit plays CDs but has issues with other functions, ensure that all connections are secure. Pay close attention to the wiring harness and ground connections. A poor ground or faulty wiring can lead to functionality issues.

3. Faceplate Connection: Even if the volume knob works, there might be an issue with the connections between the faceplate and the main unit. Disconnect and reconnect the faceplate’s connector. Sometimes, dirt or oxidation can cause a poor connection.

4. Inspect for Firmware Issues: Some models have firmware glitches that can cause features to not work correctly. While it's typically less common, search if there are updates or specific reset sequences that can restore functionality.

5. Speaker System Check: Make sure that the speakers are properly connected and functioning. If the speakers themselves are defective, they might not reproduce sound regardless of the head unit's functionality.

6. Internal Components: Since your visual inspection came up clean, you might want to look for any loose solder joints or hidden cracks on the circuit boards, especially around the control areas. If you have a multimeter, you can check the continuity of the buttons on the faceplate.

7. Service Manual: If you can find a service manual online, it may provide troubleshooting steps or internal diagrams to check specific components related to the controls that are not functioning.

If none of these solutions work, the problem may be deeper within the unit, possibly requiring professional repair or replacement.

If you're still having issues, others might have encountered similar problems! I'd encourage more members to assist or chime in with their insights or experiences!