it's time to replace the power tubes on my HT-20 head (1st version). I opened the back panel, and I've seen a large metal plate from which valves sprout. No caps or resistor are nearby.
Is it safe to perform the replacement at home, with the amp turned off and disconnected from the power outlet, or is it better to contact a technician? Is there the risk to be shocked performing this operation?
Thanks to all