> Alternator:
> Bosch 0 120 489 565 566
> K1-14V 55A 22
> 043 903 023C
>
> Greetings newsgroupers,
>
> I'm an electronics technician, not a mechanic, but I have managed a fair
> number of auto repairs over the years. My current project is fixing the lack
> of battery charging on a '79 (1979) VW (Volkswagen) Super Beetle. This car
> is equipped with a Bosch alternator, and has no air-conditioning. >
> I thought I would simply replace the alternator but soon found that it was
> not removable without pulling the engine. (Correct me if I'm wrong.) But I
> did manage to dismantle a number of items around the alternator (for the
> purpose of gaining access to the various alternator related screws and
> bolts.) I discovered that the lower left bolt holding the fan cover to the
> fan housing would be impossible to access without an engine pull. Also, I
> suspect that even if that bolt were removed, I would still not be able to
> remove the alternator because the fan would not clear its housing. (Again,
> correct me if I'm wrong.) For me, it would be far better to just fix the
> alternator in place - if possible.
>
> Anyway, I discovered that the voltage regulator is easily removable from the
> (in place) alternator, and I believed that by simply replacing the regulator
> I would have some chance of fixing the problem. But then I carried out a web
> search and discovered that all of the rectifier diodes are also mounted
> inside the alternator - and believe that a bad diode is equally if not more
> likely to be the problem then a defective voltage regulator. So, I decide
> the best thing to do is to replace all the diodes and the regulator at the > same time.
>
> What do you all think? Is this a good idea?
>
> Anyway, in my effort to remove the alternator, I tried to remove the belt -
> but not finding a way to relieve the belt tension I was unable to do so.
> Since the belt was old and showed some signs of cracking, I decided to
> simply cut it off. Now, I need to know the proper way to install a fresh
> belt. Must I remove a pulley - if so, which one, the engine pulley or the
> alternator pulley? (I see that the alternator pulley has a small "cut" in
> it - presumable provided as a place to lock it by means of wedging in a
> wrench or whatnot.) My guess is that the alternator pulley must be removed,
> but I want to check with you guys first. This may turn out to be a moot
> point because I will no doubt have to remove the alternator pulley anyway in
> order to change the diodes.
>
> And now for my questions: (You knew they were coming.)
>
> 1) Can I in fact change the diodes by removing the front of the > alternator?
> 2) Are these diodes found in groups of one, two, three or what?
> 3) Where is the best place to buy good quality diodes and regulators?
> 4) What is the truth about diode blowing and the opening of the battery > circuit?
> - Is it possible to add an external "protector circuit" to prevent
> future diode loss due to an open battery connection?
>
> Any links to pictures, manuals, diagrams etc. would be much appreciated. >
> Thanks all,
> - Stan Shankman
Run, don't walk to the nearest (on-line) bookshop and get the Bentley manual for this car. It won't show you the internals of the Alt, but will give you a clearer picture of how the engine and fan shroud are put together.
As a practical matter, the engine is best removed in order to lift the fan shroud high enough. Yes, it *can* be done with engine in car but you'd better be a contortionist. Either way means learning a whole new set of skills besides electronics.
Diode failures usually result in a short rather than open. Rather than no charging, the thing often discharges the battery...fast.
I think it's worth springing for a regulator, if you can find one.
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Or..if you're experimentally inclined, locate the brushes which contact the slip rings. Apply 1 Amp or so of excitation to the slip rings and measure the alternator output at 2500 RPM or so.
Oh, to get the belt off: lodge a screwdriver in the slot to lock the shaft. Put a spark plug socket on the shaft nut and loosen. The rear pulley sheave will come off, along with shim washers. NOTE HOW they came apart.
Speedy Jim
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