blessings to all the colleagues I got a console peavey model XR8600D it sounds good but after 30 minutes it goes up in advanced a homm strong noise and increases until the sound of the music disappears and only remains that man I have reviewed components of the pre and I have done measurements and everything well put sound directly to the amplifier plate and the same follow the fault I did to discard the preamplifier, check plate where the outputs are and everything okay my suspicion is bridge rectifier or large filter of the source, transformer in fact this console was modified in its output plates and source, they put plates made (handmade) with 4 transistors c5200 and 4 transistors a1943, a big double filter of 10.000uf 80v I gratify its orientation to be able to repair it