Probably a bad 6550 valve, sometimes you can see flashes inside the bad valve. You could try running the Leslie with just one 6550 installed. Assuming that only one of the two valves is bad, it will work with just one. Less volume, and more distortion, but it will work. If the popping and the crackling can be pinned down to just one of the 6550's in this way, change both for a new set.

On 24/09/2022 13:37, Keith Taylor wrote:

Hi!
Hope you can help me with a problem that has developed in my Leslie 145.
When it warms up after 5 minutes say, the Leslie starts popping and cracking this happens consistently with or without any music being played or regardless the position of either the MEE or speed switches. If I play, then the pop will often lead to a huge feedback type sound.
Looking in the back at the amp, the OC3 valve flashes on and off in tandem with each pop, when it is not popping the colour stays static. I have bought a NOS tube to see if that would alleviate but unfortunately the same fault exists. Please help!

Keith

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