My CQ-18T occasionally produces a loud crackling / gunshot noise, through all outputs. All channel faders spike, even the ones with nothing connected. I already sent it to the shop for repair, according to their info the main CPU board was replaced.
The mixer is back, but the issue persists. Sometimes the mixer works for many hours without problems, but then again the issue appears.
I tested this when the issue occurred:
- New blank scene created.
- Bluetooth and WiFi disabled (to exclude issues caused by bluetooth or WLAN sources)
- Everything disconnected, except studio monitors connected to Main L+R
- mp3 player (battery powered) connected to stereo input via TS cable
- Keyboard connected to inputs 15/16, but keyboard off and channels muted.
This happened while I listened to some music
- All of a sudden, persistent loud crackling noise and spiking of all channels.
- Muting the main out did not remove the noise
- After several seconds, a popup appeared saying something like “no defect identified”. I closed the pop-up.
- Spiking continued.
- Disconnected the cable from inputs 15/16. Mixer shut down by itself and re-booted 4 times, but was unable to start.
- Switched off the power and back on. Now, mixer booted correctly and there was no more noise.
I am thinking some other component might be defective:
- External power supply (checked with Voltmeter, stable 12 V) - but might it cause some issues under load, which disturb the mixer?
- Internal power circuit board
- I/O board…
Any ideas what might cause this issue? How to identify the root cause?
How to fix it?
Trouble: The device is still under extended warranty by the shop, but the shop is just saying they have tested and could not reproduce the issue, therefore it is hard to get a warranty repair or replacement.