I received this VOX AC15 type 2 with a fault after refurbishing the main amplifier. The fault was a few faults; (funny how things escalate). Low power output, crackly sound and no tremolo.
The crackly sound was the valve holder on the ECC83. A wash and brush up of all valve holders stopped the crackling.
The poor/low sound was due to a low emission EZ81 and the EL84s had seen better days, maybe a decade or so!
With those two faults attended to the next fault; no tremolo.
Slight snag found when taking the selector assembly to bits … totally unserviceable!
Nothing else for it … make a new one but it must look and perform the same as the old one. So, drawing made, out with the Veroboard … quite simple really … phase shift oscillator and a couple of switches, how hard is that. A day or so researching later and…
Values sorted and build done, testing the new apparatus and of course it works. To prolong its life all capacitors are 630volt working at 105℃. Seal the box and fill with potting compound to protect the board and components from vibration and damage.
The new controller was potted, after testing and this is the finished product.
My schematic with pin numbers and component value.