Even more Alternator woes

[green A8]

This is worse than a soap opera!

I started a thread a little while ago about a friends A8 and it's alternator problem, well it's got a whole lot worse. A second hand part was sourced and fitted by a local garage, the car started, after a few seconds the battery light glowed brightly then there was a slight grinding noise and a plume of smoke (from within the alternator it seems) one more knackered alternator for the scrap pile!

I was off visiting family at the time and returned to find irate messages on the answerphone. About second hand parts being usless blah, blah, blah

So on Monday I recovered the last fitted alternator from the upset Audi owner, just to try to see what was causing all these problems. On opening it up the slip ring was found to be badly worn and the regulator appeared to have arced, it's carbon bushes were just about worn out and very sticky in their mountings. So, I called in a few favours and raided another friends spare parts boxes, result about an hour later one semi reconned alternator. I replaced the slip ring with a brand new unit, likewise the rear bearing was also renewed. The regulator was replaced with a known to be good second hand unit, with almost unworn carbon brushes. Feeling somewhat pleased with myself I called to see the A8 owner yesterday. 'Oh you shouldn't have bothered mate' was the reply I got on showing him the results of my efforts. 'The garage are fitting a brand new alternator today' I nearly threw the damn thing at him

Got a 'phone call this morning, it seems that the garage fitted the new alternator, only for it to fry itself within five minutes. They've checked all wires and the noted corrosion spot of what I call the junction box in the front wheel arch area. Nothing of concern was found. Another new alternator is being fitted today I wonder if this one will solve the problem?

One very odd thing that seems to happen just before the alternator gives out it's smoke signal and tenders it's resignation. The sunroof opens itself without anyone touching the control switch I think the car is hexed. Anyway I've got myself a nice little 150 Amp alternator that should be good to go sitting in the garage waiting for the opportunity to expire in a cloud of smoke

Has anyone else ever had such aggro with A8 alternators? Or are we trendsetters?