I am looking for help on troubleshotting my Laney GC 60A solid state amp. If I plug my guitar to the front panel (with the amp buildin tone and volume controls etc..), the sound will cutoff sometime. If I turn the amp off and on again, it will get back to normal.

This never happens if I use the return loop with padels. The amp will not cut-off this case.

What is the potential causes of this and how can I fix it? Thanks.