MG T-ABC

I am laughing at myself, total ignoramus. This is for a TB with positive ground.
The two sockets in the dash panel, does the red one go on the left or right hole? Is the red one grounded with continuity to the metal dash panel? Is the red one hooked up to circuit #33 black wire or circuit #13 yellow & black wire?
This brings me to the most basic question concerning positive ground vehicles. Does the ground or earth symbal that looks like an antenna usually have black wires or the red (or brown or yellow with black) connected to it.
I use a micronta voltmeter, red means positive, black means ground. Of course I switch leads to test on a positive ground car but am not sure of the standard protocol (obviously).
Tim Bloomfield
TB0613 almost completed
Louisiana

I don't know about the TB... but on the + earth TC, the red inspection socket is the live one. It (and the clock) gets it's power directly from the battery via the 'B' terminal on the ammeter and is positioned on the right. The ground is via the panel but it also grounds both the map reading lights with a separate black wire.

Dashboard power sockets: factory photos show TB and early TCs have the black socket on the right. Mid to late TCs have the black socket on the left. I can’t remember the source of this info, possibly Craig Seabrook
https://www.whitworthshop.com/dashboards

Tim Jackson wrote: ↑

Wed May 03, 2023 7:37 am

Dashboard power sockets: factory photos show TB and early TCs have the black socket on the right. Mid to late TCs have the black socket on the left. I can’t remember the source of this info, possibly Craig Seabrook
https://www.whitworthshop.com/dashboards

I didn't know that...although I did say I didn't know about the TB. I looked it up in Sherrell. He doesn't mention it being different for the early TCs.

I'm looking at the TB wiring diagram in the Blower manual. Its a little confusing until you realize it is drawn from the back side, as you would view the wiring laying on your back under the dashboard, map light and speedometer on the right, 30 MPH light on the left, no tach shown at all.

The positive plug socket is on the left in this drawing, so it is really on the right nearer the driver as you sit in the car. It has the #33 Black wire, which is grounded somewhere, and also runs over to provide grounding for the 4 dash lamps. The positive plug socket is the larger internal diameter of the two sockets, and should have the red ring on it.

The smaller internal diameter plug socket is the negative and is on the right in the drawing so really on the left, nearer the passenger. It should have the black ring on it. It has the #13 yellow/black wire running directly to the ammeter B terminal, continuing on to the starter switch, and ultimately to the battery negative.

Standard coloring scheme protocol in the automotive world is Red = positive, Black = negative.

For reasons best known to MG, they put a #33 black wire on this positive socket, and used #1 red wires for the negative to the side lamps and tail lamp. Maybe there was no standard protocol in the 1930s?

If you are going to use these sockets to connect a battery charger, you want to be sure your charger wires have the right size plugs and the larger diameter plug is positive. Moss sells the plug.

Personally, I don't like the idea of these 12 volt sockets on the dashboard and have removed them.

Don't remove them Ray, Just disconnect them. At least then they will look right.
Ian

i.thomson wrote: ↑

Tue May 09, 2023 4:00 am

Don't remove them Ray, Just disconnect them. At least then they will look right.
Ian

They are long gone. I have a custom dash. My choice.