Ammeter

[Phil Read]

The ammeter on my 250 does not work. it is a Lucas C/D type will any C/D ammeter replace this or does it have to be a specific current requirement eg 50/50 30/30

[RobH]

Any ammeter will work Phil.  Ideally the amps range should be the same as the old one.  You can use a 50-0-50 to replace a 30-0-30 if you don't mind the lower indications.   

 

 

[Z320]

Hi Phil,

sorry me, why doesn’t it work, please?

Why I ask?

A friend with his 250 ask me for help because the new ammeter also did not work.

Both, the original and new one burned down in 2 seconds because of a serious electrical fault.

And if this is the case any spart part will fail immediately.

Ciao, Marco 

[stuart]

11 minutes ago, Z320 said:

Why I ask?

A friend with his 250 ask me for help because the new ammeter also did not work.

Both, the original and new one burned down in 2 seconds because of a serious electrical fault.

And if this is the case any spart part will fail immediately.

Ciao, Marco 

That is a serious fault, sounds like a dead short somewhere.

Stuart.

[Z320]

Yes, and he produced it himself 2 times.

While assembling he connected both cables on the ammeter terminals without the isulators between!

——> directly on the housing, grounded via the dashboard to earth

—> battery connected, money burned, learned nothing 

[stuart]

Just now, Z320 said:

Yes, and he produced it himself 2 times.

While assembling he connected both cables on the ammeter terminals without the isulators between!

——> directly on the housing, grounded via the dashboard to earth

—> battery connected, money burned, learned nothing 

Yikes, he was lucky the loom didnt meltdown too, or did it?

Stuart.

[RobH]

Phil - rather than jumping to conclusions here, to put minds at rest how do you know it doesn't work?

3 possibilities: 

a)  there is a bad connection to the meter (symptoms - there is no ignition, the lights don't work but the horn does)

b) it doesn't indicate because the pointer mechanism has detached (symptoms - everything works and the battery charges, just no pointer movement)

c) the high current coil has detached from the terminals inside the ammeter or possibly burned out ( symptoms as for 'a' above but the external connections look OK)

 

Edited November 5, 2023 by RobH

[Z320]

1 hour ago, stuart said:

Yikes, he was lucky the loom didnt meltdown too, or did it?

Stuart.

Luckily ground via the painted housing was very poor, 

so the current went the ground cable of the illumination of the gauge.

After 2 short circuits I found it well roasted and crispy 

My mate noticed this with „yes, it was „already different“ after the first fault“

[Phil Read]

Thanks for the advice guys. I have sorted the old one. I checked connections on the rear and they were tight, but the posts seemed slack in the case, as did one of the mounting pins. I removed the ammeter with a struggle as one of the two threaded pins that hold the ammeter to the facia was loose and just turned. On removal I realised that the needle was catching the black facia and this stopped it from moving. I stripped the unit down, tightened the electrical posts in the case. Fit a new mounting pin ( the old one was shorter than the original, it had been bodged). tested the unit and it seemed fine. Now refit and working.

[RogerH]

Good result