A time ago, I had a client bring in 2 Black Box amplifiers. Unusual to be seen here in Spain. Then, another customer drove a long way with his PYE to be serviced.
Lovely cabinet, nice lacquer etc. The set had been serviced some time ago, but was not working well whatsoever. Out with the amplifier unit and on the bench with it, A few capacitors had been changed, but the grid coupling capacitors had been left. The Hunts capacitors were rubbish when leaving the factory, let alone wanting to survive 63 years. So, replaced these straight away. The valves, EL42s and ECC83 all tested well on the AVO tester. The main fault was with the ganged volume control. Somehow, both sections seemed to have a wiper fault, with the volume vanishing at mid point. So, a NOS ganged 1 Mg log pot fitted. Not easy as the tag strip got in the way. But a bit of brute force and love got that sorted. PYE liked to cover their transformers in tar. As a result of high HT current due to those Hunts caps, the tar had dribbled all over the place. The cathode resistor was also found to be a strange value, so that was put right.
With the amp working well, attention turned to the lovely BSR UA8 deck, the best deck on God’s planet. All the usual clean ups and lubrication. The idler boiled for 10 minutes and a spring retention got the set working spot on. Reassembly and a lovely machine, set for the next 60 years.