Ammeter/wiring problem on my 8n

Biffer5

Member
I always feel like a real dufus presenting my latest problem as I always seem to first struggle with even the simplist problems.....

The wiring on my resister block has been coming loose. Specifically the three wires on the bottom. So I thought I would take off the nut, replace the screw and nut and make it better. Well I did that and the damn thing started smoking. Specifically, the yellow wire going to the ammeter. I have no idea what shorted as I didn't think I did anything differently from what was there. I did take the block off and (but not the other wires) and screwed it back on after attaching the three wires back. So now I have a melted yellow wire and, what's worse, an ammeter that is now showing zero, I mean the guage is all the way to the left as far as it will go. I'm assuming it is burned out?

Here is a picture I took before "fixing" it. If anyone can give me some help here I would appreciate it.

ammeter.jpg


Here is the link if that does not work:

http://peytonart.com/images2/ammeter.jpg

Thanks!!
 
The head of the screw that you replaced is very likely shorting to the metal part of tractor that block is attached to. Not properly countersunk.
 
(quoted from post at 14:56:34 08/11/20) The head of the screw that you replaced is very likely shorting to the metal part of tractor that block is attached to. Not properly countersunk.

I bet that's it. . It's a round head and I thought it was sunk enough but I bet it isn't.

How about that ammeter? Burned out?
 
(quoted from post at 18:12:23 08/11/20)
(quoted from post at 14:56:34 08/11/20) The head of the screw that you replaced is very likely shorting to the metal part of tractor that block is attached to. Not properly countersunk.

I bet that's it. . It's a round head and I thought it was sunk enough but I bet it isn't.

How about that ammeter? Burned out?
ost likely. Only wire limited the current
 
(quoted from post at 16:27:54 08/11/20)
I'll buy a new one but just curious, will the tractor still start with that ammeter burned out?

as long as the shunt is intact, yes. the shunt carries 99.9% of the current, only 0.1% goes through the ammeter itself, they are typically a 1mA mechanism
 
Thanks all.

One last question... could you steer me to where I can get a new ammeter? Don't see it on this site.
 

I don't know if anyone makes reproductions of the original meter, but there's a wide range of similar sized meters available in the marine market.

For instance...
https://www.defender.com/product.jsp?name=vdo-marine-vision-black-60-amp-ammeter&path=-1|311|2349076|2349077&id=1674468
 
Sorry that happened to you. You might consider ordering a new resistor block along with an ammeter. Then everything should stay tight.
 
(quoted from post at 09:24:20 08/12/20)
(quoted from post at 12:01:31 08/12/20)
I will.

What does the resister block do?
elps stabilize coil current.

more specifically, it LIMITS coil current.

the resistor is designed so it heats up, initially its lower resistance so you get more/hotter spark when you start the engine, then as current flows, it heats up and raises the resistance to reduce the current so you don't end up burning out the coil.
 
(quoted from post at 20:42:05 08/12/20)
(quoted from post at 09:24:20 08/12/20)
(quoted from post at 12:01:31 08/12/20)
I will.

What does the resister block do?
elps stabilize coil current.

more specifically, it LIMITS coil current.

the resistor is designed so it heats up, initially its lower resistance so you get more/hotter spark when you start the engine, then as current flows, it heats up and raises the resistance to reduce the current so you don't end up burning out the coil.
orry, but you only have a 'simple' understanding. As the coil heats, current would decrease so much as to reduce spark energy to only about 60%, but withthe temperature sensitive ballast, it also functions to prevent such a reduction.
 
Did you have power ON when you switched around wires? Have your ESSENTIAL MANUALS handy? Wiring diagrams shown in all of them.

FORD 8N TRACTOR WIRING DIAGRAMS:
MXLPPwsh.jpg
CfuUUP3h.jpg
rxNF128h.jpg
lz8RwfQh.jpg

TBC19a5h.jpg
*PICTOGRAM courtesy of JMOR

FORD OEM BALLAST RESISTOR -USED ONLY WITH FRONT MOUNT DISTRIBUTOR:
swlv82hh.jpg

FORD 8N TRACTOR ESSENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS:
qI9P22kh.jpg

Tim Daley(MI)
 

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