SparkFun Forums

[Artificer59]

Hi,
I have an early MP3 trigger (dated 3-1-10 on the back). I've had this in storage, unused since I got it until yesterday when I got it working. All went well, played direct through speaker using the switch, played through amplifier using the switch and played happily shorting across the trigger pads. Then I attached an RF relay board to close just one trigger. The MP3 trigger power LED lit for a few seconds then went out. I tried this several times with the same result. I then disconnected everything from the board and attached power with the same result; power LED on for 3 or 4 seconds then it goes out. (Sometimes I get a tiny flicker on the status LED.) I tried uploading new firmware but again the power LED goes off after a couple of seconds (though the status LED does flash quickly for that time).

Any ideas?

[robertsonics]

As you can see from the schematic (link on the product page) the power LED is across the output of the 3.3V regulator. The processor and its firmware has nothing to do with whether it illuminates or not. If that LED is not illuminated, you have no 3.3V and the processor isn't running in any event. The simplest explanation is that something is wrong with your power supply, or you're shorting something and the regulator is shutting down.

In fact, by trying to upload new firmware when you have a power supply issue, you may have corrupted the firmware. You shouldn't be able to corrupt the bootloader, so that's ok - just keep in mind that once you fix the real issue, you may have to reload a good copy of the firmware before the board works properly.

[Artificer59]

I think I've fried the onboard regulator or one of its associated components. Varying the input voltage, the regulator output varies but does not get above 2.8v. Applying a regulated 3.3v direct to the board gets it working. Firmware reloaded and the board is working, hurrah!

I think I'll stick with an external regulated 3.3v supply, my eyes aren't up to replacing the SMT components!

Cheers
Chris

[Artificer59]

Spoke too soon. The board works with the switch but the audio decoder chip is too hot to touch and the triggers do not function.