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I received for rebuilding/repair a pair of LS10 amplifiers. These were based on the Wiliamson design but had been worked upon many times since their first commision.
My first inspection was to see odd value components scattered around the amplifiers, in an attempt to stop parasitic oscillation, is my best guess.
The main smoothing capacitors had,
many years ago, been replaced. 
These amplifiers were dated around 1954/5, I found one original capacitor with an early 1954 date code.
I decided the boards that had been overworked and the undersides were covered in glue to stop the cracks were beyond repair.
I made some new ones, 
using original materials (Paxolin) 
and replaced the descrete components on them.
Completely removed the components, old capacitors and most of the wiring due to rubber wires are very brittle when 70 years old.
Not a pretty site!
I spent a while drawing the schematic and rewired the amplifiers fitting a new PowerCon mains socket and Nutrek Phono input socket.
New switched volume control and than time to test them.
I tested the amplifiers using donor valves; EF86, ECC81 and two 6V6GTs.
No hum, good clean sound and plenty of power in both amplifiers. That was pleasing after all my time spent on them.
On fitting the original valves; CV2901, CV455 and two CV1075 plus a CV1377 rectifier, back to the glorious sound of a proper valve amplifier.
Here are a few shots of the old becoming the new.
Ready to go.
I hope you found my weeks work interesting.
My first inspection was to see odd value components scattered around the amplifiers, in an attempt to stop parasitic oscillation, is my best guess.
The main smoothing capacitors had,
These amplifiers were dated around 1954/5, I found one original capacitor with an early 1954 date code.
I decided the boards that had been overworked and the undersides were covered in glue to stop the cracks were beyond repair.
Completely removed the components, old capacitors and most of the wiring due to rubber wires are very brittle when 70 years old.
I spent a while drawing the schematic and rewired the amplifiers fitting a new PowerCon mains socket and Nutrek Phono input socket.
New switched volume control and than time to test them.
I tested the amplifiers using donor valves; EF86, ECC81 and two 6V6GTs.
No hum, good clean sound and plenty of power in both amplifiers. That was pleasing after all my time spent on them.
On fitting the original valves; CV2901, CV455 and two CV1075 plus a CV1377 rectifier, back to the glorious sound of a proper valve amplifier.
Here are a few shots of the old becoming the new.
I hope you found my weeks work interesting.
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