Randall RD5C hums

[Pixel]

I picked up a nice Randall RD5C, everything works as it should except it hums a little bit too much. A quick examination shows that C62 and C63 in the DC heater supply are bulging and leaking. In the amp C62 and C63 are only 3300uF while in the schematic they are 4700uF.

Should I just put a pair of new 3300uF in the amp and call it a day or should I go to 4700uF? The 3300uF caps look original and I can see no evidence this amp was ever serviced before.

I will do an ESR test of the rest of the electrolytic caps once I get the PCB out, but unless they test really horrible I will leave them alone.

RD5 {Schematic}.pdf

[Jon Snell]

No need to remove the pcb to test the heater capacitors. Remove the valves and unplug CN13, that's it.
The capacitors bulge on the top end and split the cutaway on them.
4k7uF 10v are less expensive than 3k3uF 10v. That is why they were replaced in the factory.
If you remove the pcb, replace C5 & C53. That will save you the effort at a later date.