Channel Selector Switch

1. Check the Channel Select Control:

This is the most likely culprit. Make sure the Channel Select knob or button (depending on your amp model) is being turned or pressed completely. Sometimes a slight nudge might not fully engage the switch.

2. Verify Cable Connections:

Ensure your instrument cable is securely plugged into the input jack of the channel you're trying to select (usually labeled "Input 1" or "Channel 1"). A loose connection can mimic channel selection issues.

3. Consult the User Manual:

The Fender FM25 DSP user manual should have a troubleshooting section for channel selection problems. It might mention specific steps or checks to perform for your model. You can find the manual online by searching for "Fender FM25 DSP user manual" or similar terms.

4. Fuses (Less Likely):

While less likely, a blown fuse could potentially affect channel selection. The user manual should have a diagram showing the fuse location(s) and specifications. However, a blown fuse would likely cause other issues with the amp besides just the channel switch.

Not Recommended: Trying to Fix Yourself (Unless Comfortable):

If the above steps don't resolve the issue, it's best to take your amp to a qualified technician for further diagnosis and repair. Opening the amplifier yourself to access internal components is not recommended unless you're comfortable working with electronics.

By following these steps, you should be able to identify the cause of the channel selection problem on your Fender 25 DSP. If you're not comfortable troubleshooting further or the issue persists, consult a professional for repairs.