> My questions are 1) the only dash instruments that have actual ground wires
> attached to the instrument body are the two who's lights are working -
> coincidence?,
Probably not ... what have you done to ground the other instruments ? All of
the regular dash lights require a ground of some sort, and as I recall they are
all grounded through the instrument body. Even though I believe the factory
relied on the mounting clamps to ground the speedo & tach to the dash, IMO it's
worth adding a ground wire to them. Not sure where to tie it on a 4A, on a TR3
there is a ground clamp on the back of the center dash panel.
> 2) can it possibly be that each and every bulb that I have
> (I've tried 10 different bulbs) is burned out?,
Highly unlikely IMO, but the thing to do is test them. Use the ohmmeter
function of your DVM (if you don't have a DVM, get one ! They're under $10 at
Horrible Freight, even less on sale, and worth every penny. I keep one in each
of my LBCs.) If you find continuity through the bulb (less than 100 ohms) then
the bulb is OK.
> 3) are the small instrument
> dash lights actually grounded through the small clip to the instrument?,
Yup.
> 4) it seems to me that the bulb needs a ground - but on the signal indicator,
> there is only one wire and it goes into a plastic holder???
I'm not intimate with the 4A, but if it's the same as a TR3 (as it looks to be),
there should be a ground wire on the signal indicator. You mentioned soldering
in the bulb holders ... the ground wire would not be included with either the
harness or the holder, but is required. Fortunately it's black, and you can buy
suitable stranded black wire at any auto parts store (likely even WallyMart).
18 gauge (AWG) is fine, 16 or 20 would do too. 14 is kind of stiff. Get an
assortment of solderless terminals while you're there, you'll want ring
terminals for grounding the speedo & tach. If you go to Radio Shack you can buy
just the kinds of terminals you need, but they'll likely wind up costing more
than the assortment.
Note that the red IGN warning lamp is a special case, it doesn't get grounded.
Instead, one side goes to the ignition circuit, and the other side goes to the D
terminal on the generator control box. The light comes on when there is a
difference in voltage between these two points. If you've not connected the
generator (or control box) yet, the light won't come on. One way of looking at
it ... the warning light gets grounded through the generator armature winding,
when the generator is not generating.
HTH
Randall
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