Electrolytic Capacitors will be used in most (if not all) guitar effects pedals and amplifiers, whether tube, solid state or hybrid. They will be used for decoupling amplifier stages - DC blocking - and filtering of power supplies. Capacitors store energy and, in the case of guitar tube amplifiers, they can be operating at voltages 500VDC - and higher!! When you switch your amp off, this voltage can be stored for hours, and can result in a severe, if not fatal, electric shock.
Achtung, Baby!! ALWAYS DISCHARGE CAPACITORS BEFORE WORKING ON ANY AMPLIFIER!
Or, alternatively, speak with our SERVICE AND REPAIR team to have your amplifier inspected, tested, modded or fixed.