Hum - what's the cure?

Take the ground wire off between arm and phono and see what happens.

Oh, yes I see.

Hmmm, not sure then

See if the turntable earth is also connected through to the cartridge leads.
It needs to be separate.

Do you have the hum without the TT connected to the phonostage? If not it shows you are creating a loop when the TT is connected.

Just unplugged the turntable from the phono and no hum, so what's my next step?

Oh I see I've got to check the earth wire is connected to the cartridge leads  

Does that mean removing the tonearm?

I did get some hum to begin with, Alan checked it out in his system and all was well. Can’t remember what we did though.

Gary

Ground the tonearm onto the case of the amplifier. IIRC its a lack of real ground in the unit due to being powered by a wall wart.

Now you've given me a job, the unit is gloss painted and so is the base, I've taken the base off and tried attaching the ground wire to the base, unfortunately the screws are too small to hold the wire, and I don't have any washers small enough to help attach the wire using the Y attachment. I'll give it some thought, may have to try and get a very small washer of some sort, but that won't be today.

Oh

Still, worth a try

It's still worth trying.

Someone shout in an alarmed fashion if I’m way off base here and suggesting something dodgy, but would an alternative be to run a wire to the earth pin of a regular mains plug?

Check for continuity between.
Chassis and arm.
Chassis and internal psu/ transformer.
Chassis and wall socket.
Cart body and arm.
Arm and wall socket.
Cart and wall socket.

Then let us know which of them has continuity. Then we can tell you which one needs lifting and how you should earth to the phonostage.

In my deck motor is gnd to mains only, and everything else goes to phono. So it's effectively two parts. If your motor is gnd to Chassis and the arm is too you need to break that link on the arm, or run the 5th wire back to the chassis.

If your cart body is gnd to arm then you have to break any link from arm to everything except the phonostage.

Do the 6 tests at the start of post first

Haha, same as me.

Just futz around with the grounding until the hum goes away.

I have just connected the earth wire from the tt to the ground terminal on my Russ Andrews distribution block and the hum increased, comparable with connecting to the ground terminal on the Firebottle OTP2: Will have to look on YT to see if I can find more info on using my multimeter  

I’ll pay for you to send it to Alan if you’re still having problems.

Gary