Hey guys,

Is there a positive or negative side or power feed/ground terminal on these gauges (back of quad gauge from 51 F-1--oil press, water temp, fuel qty)? They seem identical to me. See the pic below. I have voltage reducers attached for my 12 V system, just FYI.

Thx, Tyler

 

As you may be able to tell in this picture, the three gauges are connected to the ignition switch GA terminal with the bus straps connecting all three gauges together for power.


The open terminal on the Gas, Temp and Oil pressure gauges goes to the senders for each.

 

OK, I get that...sorta. But does it matter which post on each gauge gets the power feed and which one goes to the sender? And if so, how do I tell which is which?

t

 

Well, I think it matters. On a 6 volt positive ground circuit, -6 volts from the ignition switch is applied to the 3 terminals with the straps. The sending units go to the other terminals.

The terminals with the straps are (in your pic) the one next to the black wire on the upper left gauge (lower left terminal) straight across the the right to the upper right gauge (lower right terminal) and from there to the lower right gauge (upper right terminal). The straps form an L shape (if viewed from the front).

I don't think the gauges (except the ammeter) care which way the polarity goes. So a negative ground 12 volts through the reducers should work correctly wired like I said.

Someone who has done the 12 volt conversion should chime in here.

 

I don't think it matters. Remember Tyler's thread about the heating element inside? It doesn't care which way the current is flowing.

I'm not real clear on what those resistors are doing tho. Are the ends of the "circuit board" connections? or just supports? Is the black wire the 12v feed? As I recall, those need a ground, too.

 

I may be wrong, but id believe polarity will make a difference. DC always has polarity..AC does not. Hook up voltage backwards to a DC meter, and it will probably peg in the wrong direction. Just my thoughts.