I have a Hafler DH500 that has always worked perfectly. I turned it on a few days ago and it shut off (thermal shutdown with power switch light blinking every 3 seconds) after about 15 seconds. I disconnected all inputs, puled the cover, checked all fuses everything looks fine on a once over. No obvious scorching on any components either.
Turning it on again, the left channel mosfets (all of them) get very hot to the touch in only about 5 seconds. All right channel msofets are cool. If i pull slow blow fuses for the left channel, and turn the amp on - no thermal overload and the right channel plays perfectly.
Thoughts on what to check and how to do it? I am pretty competent on the electrical diagnosis side. I do have a high quality Fluke DMM but no scope.
Thank you!
Todd
Turning it on again, the left channel mosfets (all of them) get very hot to the touch in only about 5 seconds. All right channel msofets are cool. If i pull slow blow fuses for the left channel, and turn the amp on - no thermal overload and the right channel plays perfectly.
Thoughts on what to check and how to do it? I am pretty competent on the electrical diagnosis side. I do have a high quality Fluke DMM but no scope.
Thank you!
Todd
Instability. Something has upset the compensation and it is a RF oscillator. It will fry your outputs about the time you get a foot from the power switch.
Get a variac so you can creep up on the power before it blows up to troubleshoot. Borrow a scope. Download the schematics.
Get a variac so you can creep up on the power before it blows up to troubleshoot. Borrow a scope. Download the schematics.