Grounding, non-conductive chassis

[theskintman]

I have laid out my simple se on a piece of hardboard as a prototype, and want to check how I should ground the transformers.

Should I run a wire from the laminations to the earth on the mains socket? Is that enough?

I won't have a power switch or volume control yet, so it's really just the trafos and valves on display at this stage...

[rknize]

It's a good safety precaution, yes. I usually just put clip leads on the screws and tie them all to a common point and is tied to earth ground.

[John Caswell]

Hi Skintman,
Just fit a solder tag under one of the fixing screws of the various txs chokes etc(Making sure any paint is removed) and run a wire to the mains socket earth. It is probably not necessary as all current transformers etc are usually tested for insulation between windings and also windings to core, but best to be safe.

John

[Ian444]

Wiring Diagrams

"GROUNDING

The grounding is very important to make the amplifier safe and eliminate hum. Any metal object that can be touched MUST be connected to the GROUND terminal on the power receptacle. VERIFY this connection with an ohm meter BEFORE powering up the amplifier. A shorted transformer could be LETHAL if not grounded, there could be hundreds of volts on the case. Leaky insulation in a transformer, or capacitor could put lethal amounts of electricity on the case, the volume control, the speaker wires, or the input jacks (electrifying the case of your CD player). Check all exposed metal for less than 1 ohm of resistance to the center terminal of the power connector. Do not operate the amplifier until this is verified!

A separate ground wire from each transformer case, capacitor case, and the volume control housing, to the GROUND terminal MUST be run if a non conductive chassis is used. If a metal chassis is used It should be securely grounded. The best place to make this ground is at the input connector. To avoid hum, this should be the only connection to the chassis. All metal objects (transformers, supplemental cap, choke, volume control, etc) should have a good paint free contact with the chassis. Again, verify this with an ohm meter before using the amp."

Quoted from the Tubelab.com website.