Alternator problem?

["Evan Bottcher" <evan@domain.elided>]

Hi guys,

I have an electrical problem in my Alfasud (nahhh - I don't believe it).
It's only just started the last couple of days.  The car has always had
fairly dim headlights at idle, which brighten up when I rev the engine up.
However in the last couple of days when I have the lights on (and
particularly when drawing a lot of other current, eg. radio on, wipers) they
dim almost completely.  It's not a consistent problem though - if I sit at
idle they act normally for a few seconds then *pop* everything goes dim -
even the tacho drops to zero, the radio cuts out etc.  until I put my foot
back on the accelerator.

My understanding of auto-electrics is limited to reading a wiring diagram
and looking for corroded earths.  My immediate reaction is to think the
alternator is at fault - ie. not delivering the correct amount of voltage at
idle.  I think something similar might happen if a component was shorting
out, although the extra current that would flow in that circumstance would
cause a fuse to blow?

Can anyone help with a testing procedure?  I'm in the dark (chuckle).

thanks,

Evan Bottcher
Melbourne, Australia
'69 1750 GTV
'77 Alfasud Ti
http://alfasud.globalvision.com.au/asud

------------------------------