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RE: adding an ammeter to a RBI

To: barneymg@ntsource.com, Gonaj@aol.com
Subject: RE: adding an ammeter to a RBI
From: Duinhoven_Hans@emc.com
Date: Wed, 25 Oct 2000 02:00:35 -0400
Really Barney,

You've put a lot of effort in this.
I only was quoting the advises I got from the list earlier.

You don't like to have unfused wires carrying heavy current in the dash.
Well let me tell you a story with the standard MGB wiring I got:
While I just started with the first attempts to fix the MG electrics, almost
nothing worked in the GT. So I thought: "why not getting some voltage from
the fusebox (red wire = lights) and have a wire temporarely run to the
ventilator motor and see if it starts.

Well it started, but lots of smoke came from the dash immediately as well.
My eldest son warned me.
What happened?
Pure bad luck and ignorance.
A day before I had made the heater valve cable lose on the dash side.
The cable slipped away and I did not take care of that (stupid!).
The cable with a metal outer cableframe so being ground in this way touched
the rheostat.
So when voltage was applied to the fusebox, the voltage at the rheostat was
grounded.
BEWARE THIS IS UNFUSED WHATSOEVER! I cursed the MG electrical designers!
Fusing in this circuit only is done to the main lamps and the sidelamps and
rearlamps including license plate lamps. The dashlights are not fused at
all.

I had to repair the wiring loom - had to take out all the gauges (except the
oil pressure one) to get the job done. It has cost me hours of work.
The damage luckily was limited to one burnt wire only. The switch was
slightly damaged, so I have built in a relay to protect the switch contacts,
also because I use H4 duplo lamps instead of the sealed beams. H4's use some
more current.

So Barney standard electrics on MG's are not really safe!
I've studied for electrical engineer, and I have seen quite some violantions
against the basic rules how to fuse electrical systmes on cars including
MG's.

Cheers,

Hans


>>>>>>>>>>>
I personally do not like the analog type amp meter, simply becasue I don't
like having unfused heavy gauge high current wires routed up behind the
dash in the passenger compartment.  If there should ever be a short in
these wires, and a meltdown and/or fire to ensue, I would much prefer to
keep the problem out of the passenger compartment.  This is why I voted
$.10 for the volt meter and only $.05 for the amp meter.

Incidentally, I do like the idea of a digital volt meter pluged into the
cigarette lighter, except I can see possible problems maintaining a good
electrical connection if the lighter is actually used and the socket gets
cooked and dirty.  As a matter of reliability I would still rather have a
digital volt meter hard wired.

$.02,

Barney Gaylord
1958 MGA with an attitude
    http://www.ntsource.com/~barneymg
>>>>>>>>>>>>>>>>>>>>>

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