Mo Murphy Posted October 19, 2005 Share Posted October 19, 2005 On my 300 tdi alternator ; is the regulator in the brush/diode pack screwed to the back or is it elsewhere inside ? Mo Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 19, 2005 Share Posted October 19, 2005 The regulator IS the diode pack, innit? Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted October 19, 2005 Author Share Posted October 19, 2005 I dunno Fridge, that's why I'm asking !!!!! Mo Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted October 20, 2005 Author Share Posted October 20, 2005 Come along now, all you highly skilled home mechanics, surely someone can lay our minds at rest with an answer ? Mo Quote Link to comment Share on other sites More sharing options...
02GF74 Posted October 20, 2005 Share Posted October 20, 2005 The regulator IS the diode pack, innit? yes and no. An alternator is a multi-phase AC generator, 3 phases being the standard on older alternators - not sure what it is on the new fangled modern ones but probably 3 as well. There will be 6 diodes to rectify the AC to DC followed by some diode/transistor gubbins to clamp the output voltage to sensible amount plus to sense the state of battery charge thus regulating the charge current to it. Not to mention the charge warning lamp plus tacho ouput on some models. Now where and how this electronics is housed varies per model. Some have individual rectifying diodes and a separate regulator, usually a black box other modern type may have regulator and rectifying diodes in one box. Is your alternator like the lucas A127 ? If you remove the end cover, you should see the regulator and if you look hard, the diodes too, maybe. Quote Link to comment Share on other sites More sharing options...
darthdicky Posted October 20, 2005 Share Posted October 20, 2005 Not sure if this helps, but the brush pack is the black and silver bit held on with 3 small screws on the left in this pic: (Ignore the text) Not totally sure what alternator that is though! Richard Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted October 20, 2005 Author Share Posted October 20, 2005 Thanks 02 and Dicky but I'm still no wiser However, we now have a photo ! Ok Dicky, yes that's the diode/brush pack indeed, looks just like mine Does this bit regulate the output voltage ? Mo Quote Link to comment Share on other sites More sharing options...
Les Brock Posted October 20, 2005 Share Posted October 20, 2005 Short answer..... Yes Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted October 20, 2005 Author Share Posted October 20, 2005 Thank you Les and thanks to all for trying Mo Quote Link to comment Share on other sites More sharing options...
02GF74 Posted October 20, 2005 Share Posted October 20, 2005 Thanks 02 and Dicky but I'm still no wiser However, we now have a photo ! Ok Dicky, yes that's the diode/brush pack indeed, looks just like mine Does this bit regulate the output voltage ? Mo the piccy looks like a lucas a127 or a133 (differ in body perhaps but also in amps supplied - it gets more confusing since alternators wtih same number can delvier more amps too!) I learnt someting today - the brush pack houses the regulator too so should be easy to replace, see here Quote Link to comment Share on other sites More sharing options...
simonb Posted October 20, 2005 Share Posted October 20, 2005 The arrowed bit is the combined brush box and regulator - less than £10 to replace.. Rectifier is inside the main body. As load from battery increase, its voltage will drop, alt senses this and increases the voltage and current to the rotating part via the slip rings. This is the field winding, this induces more output current in the output winding (in the casing) which will restore voltage at battery. Output volts of alt should be constant to better than 1v variation. Quote Link to comment Share on other sites More sharing options...
VERY OLD DISCO Posted October 20, 2005 Share Posted October 20, 2005 If its done loads of miles, over say, 100K its probably worn out, bearings slip rings brushes, etc, all wear out. A full recon will cost about £50, and it will last a lot longer. But not if you keep dipping it in mud klike the one in your picci :-) Geoff Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted October 21, 2005 Author Share Posted October 21, 2005 Geoff, these are relatively new eg <5k miles. The regulators don't like water very much, do they ? Mo Quote Link to comment Share on other sites More sharing options...
02GF74 Posted October 21, 2005 Share Posted October 21, 2005 If its done loads of miles, over say, 100K its probably worn out, bearings slip rings brushes, etc, all wear out.A full recon will cost about £50, and it will last a lot longer. But not if you keep dipping it in mud klike the one in your picci :-) Geoff In theory t should only be the brushes that wear out - these are carbon. the first a127 I source from scrappies had what looked like copper grease inside it - when I remove the brush/reg. combo, it was the copper slip rings that had been worn out . Took it back, got another all for the princely sum of £10. >>>> The regulators don't like water very much, do they ? Not sure of the construction here but I would have expect the components to be sealed in epoxy - it may be that the ali plate and black plastic(?) are sandwiched together - not a good design then. The voltage generated by the alternator is much more than 12 V so higher voltage like water less. ((seem to recall reading somewhere it is over 100 but that wold mean large losses in the rgulatro so can't be that much surely?) Quote Link to comment Share on other sites More sharing options...
simonb Posted October 21, 2005 Share Posted October 21, 2005 If the regulator packs up, the alt can produce a 100v output which then fries the diodes. The output should never be more than 14.5v. Bearings are not more than a few quid each, the rear one is a roller cup type which is a bit trickier to find. Just rebuilt 3 alts over the last few wknds, (2 landy, 1 not!) for £20 each, all as good as new. If any one is near Portsmouth and wants theres done let me know, usually only takes an hour. I have 200/300Tdi ones as spares/swap. Quote Link to comment Share on other sites More sharing options...
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