K8020 preamp

Why do I have a hum on the lefthand channel only? All inputs work normally (right and left). I borrowed a 'scope and noticed a sign wave on V1 at the junction of R14 and 18. Amplitude was over 20 mV per centimeter at 50Hz.

Edited the post to be more readable

Use proper punctuation
Avoid typing everything in uppercase

Do you get the same amount of ripple if you measure on the same point on the other channel?
Have you tried swapping the valves?

thanks for your reply, yes the valves were swiched over to no avail. the ‘ripple’ is only on the left hand channel, measured at the same point on both valves. no input was plugged in, inputs (unloaded) were selected one at a time ,and the hum measured was the same. i did suspect a 47 uf electroletec but your ‘spares’ dept state that no spares are avilable? do you have any more advice please

I would suspect that cap too.
If you supply an address, we can mail a spare cap.

VEL448: Post edited to protect the innocent. We’ve taken note of your personal details.