Nikon SB-26 Flash advice?

I have just bought a Nikon SB-26 and it emits a high pitched whine when switched on. This is constant noise, not loud but audible in a quiet room. Is this a fault or just 'par for the course' in investing in an older second-hand model.

I'm very happy otherwise but would be keen for a refund if this is a fault.

Any advice gratefully received.

All bigger flash guns have a small whine, it's part of the high voltage circuit needed to drive the xenon flash tube. You should exercise your flash guns for at least an hour every 6 months, by the way, to keep the components from degrading.

That is the flash charging up it's capacitors. It's quite a common thing of big flashguns, especially older ones.