Note that it is fitted with PPMs so it must have been originally intended for a broadcast application.
That model (the 62/3) was the mixer model immediately before the introduction of the 828 Mk1 and the circuitry is very similar; the mic amp circuit (shown on this ‘subject’ in an earlier post) uses the same transformer as all the later 828s.
I would NOT recommend replacing capacitors unless they are faulty; as I have said often, capacitors have extremely long lives unless they are subjected to high temperatures. Old valve equipment often needed ‘recapping’, but I rarely come across faulty electrolytics in equipment that runs at normal room temperatures.
As for power supplies, I don’t want to get into recommendations. When I am repairing/updating equipment I often use Chinese manufactured switch-mode supplies but it’s not that simple; these supplies are reliable and efficient, but they often produce awful interference radiation that is not simple to deal with. If you are not experienced in dealing with power supplies generally, then be wary.
I believe the 62/3 mixer needs just a single 22 or 24V DC supply.