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!
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With those two faults attended to the next fault; no tremolo.
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Slight snag found when taking the selector assembly to bits … totally unserviceable!
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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…
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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.
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The new controller was potted, after testing and this is the finished product.
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My schematic with pin numbers and component value.

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