Hum in a Twin Reverb

[CB Amp]

Hello,
I've got a problem of hum (50Hz hum, I live in Europe) in a 1968/1969 TR.
It had a AC568 circuit (even if the tube chart says AB763), and I converted it to AB763.
I've changed all the electrolytic caps with Sprague Atom (new of course), and all the coupling caps. It had BY127 rectifier diodes, I tried new UF5408, same hum.
I've checked all voltages, tubes, everything seems to be good, but always this hum...
Does anyone have an idea of what happens ? Bad power transformer ?....
Thank you very much.

[Andy Le Blanc]

take a good look at the 6.3 filament supply..... install a hum pot and make a
V+ source if you have to......

[billyz]

I know this should make no difference but. I have corrected hum issues in this amp by making sure all the filament leads are the same polarity. Also, check the Choke, I have had a few that caused hum as well. And the reverb circuit is notorious for picking up hum. You can add shielded input wiring as well. Lead dress is very important too. many of these late 60's fender have sloppy wiring . Andy's reply about the Filament supply is right on too.