DJM250-MK2 audio output problems

Update: same for the speakers, only the right side output comes clean in the speaker and earphones. The left side is noisy sometimes and sometimes doesn't come out at all. 

Did you install the drivers for it first?

This is not normal behavior. If you're getting audio on only one channel (headphones: right only, speakers: left only with heavy noise), it is most likely a hardware or connection issue rather than a mixer setting.

Here are a few things to check:

1. Headphones
   • Try a different pair of headphones that you know works correctly.
   • Make sure the headphone plug is fully inserted into the PHONES jack.
   • Check that the headphones use a standard 3.5 mm TRS plug with the supplied 6.3 mm adapter (or a native 6.3 mm TRS plug).
2. MASTER2 Output
   • Verify that you are using the correct cables for the RCA MASTER2 outputs.
   • Swap the left and right RCA cables to see if the problem follows the cable or stays on the same mixer output.
   • Test the speakers with another audio source to confirm they are working properly.
3. Mixer Settings
   • Make sure the MASTER LEVEL is turned up.
   • Confirm the channel faders, TRIM, and crossfader are set correctly.
   • If possible, test both turntables independently to rule out a source issue.

If the same symptoms occur with different headphones, different basket random cables, and different speakers, then the mixer may have a faulty headphone output or master output. In that case, I would recommend contacting the retailer for an exchange or reaching out to Pioneer DJ/AlphaTheta support for a warranty inspection.

To help narrow it down, could you let us know:

• Are you using the original power supply?
• Do both channels behave the same way when you connect a different audio source (for example, a phone or media player) to a LINE input?
• Is the unit brand new, or was it purchased used?