Re: Alternative to rebiasing...
After reading this thread, a couple of safety tips come to mind:
Electrical safety gloves are thick and very expensive. They are rated for voltages higher than you will find in a typical amplifier. They are awkward and unnecessary.
On the other hand, using cheap rubber ‘work’ gloves can be dangerous as they might contain materials other than rubber (i.e. vinyl, nylon, etc) which could melt onto your skin in the event of an arc flash. Cheap gloves might also be coated with dry lubricant (to keep the gloves from sticking together). Some coatings could be electrically conductive.
Better to use you clean dry bare hands. Make sure you are not wearing any jewelry (rings, watches, etc) Electrical contact with a gold ring will not only guarantee shock, but deep burns.
Use meter leads with clips so you can make the connections with power off. Connect the leads, power on and take your measurements.
When reaching into your amp, use only one hand (put the other in a pocket). If you should get shocked, it will be localized to your hand. If you’re holding on to the chassis with one hand and ‘probing’ with the other, there is a good possibility that your heart will become part of the circuit.
Don’t assume a capacitor is discharged, measure it with your meter. If the cap is still charged, jumper a 5w 10–20k resistor across the terminals and wait for a few minutes then measure again. Don’t use a screwdriver.
Working on amplifiers is not like disarming bombs. It isn’t all that dangerous if you use common sense and understand the risks.