Voltage regulator.....anyone an electrician?

[doffo25]

Ive had charging problems...initially the alternator wasn't charging. I found on stripping it down that there was a bad earth on the diodes. It is now working but I'm getting 18.5V across the battery when engine running.
So I've now turned my attention tp the voltage regulator as shown in the pic. Ive read that its fairly easy and cheap to replace the diodes and transistor...., Ive easily found all parts apart from the fawn coloured capacitor (?) which appears to have been fried.(small pool of gunk under it)
Printed on it is ITT-GB PMT/2R and on the reverse .22/100.
So my question is have any of you tried to repair one of these and what do these numbers mean?

Thanks!

David

Image below

[cactusman]

0.22uF 100 volts. Get a 0.22uF polypropylene capacitor with a working voltage of 100 volts I do wonder if the gunk is actually glue holding it firm against vibration. Plastic film capacitors don't contain anything that can ooze out. Your cap may be fine....they are pretty robust.

[malcolm]

Isn't it easier just to buy a new regulator? Don't think they are that expensive. Or is this an originality thing?

[AussieEtype]

I rebuilt mine with parts from an electronics parts supplier about 30 years ago and it is still going well. However 18v straight from the alternator seems a bit high.

[doffo25]

Thanks Julian,,,,it dosent look like glue (but it might be!) I have noticed that although it looks un-corroded there is lots of corrosion between the spade terminals and the circuit board so Ill clean them up and test it without changing any transistors etc.
....and yes it is an originality thing.....all components on car appear original and id like to keep it that way if possible.
Thanks guys for your replies and Ill post on the retest.
...Oh and one more question...does the alternator generate an unregulated voltage (ie 18.5v in my case) and if working correctly the VR regulates this back to around 14v....or how does it work?

best

David

[cactusman]

The alternator will generate 18 or more volts if the regulator is dead....and this voltage will rapidly damage the battery. Provided the regulator is working as it should the voltage at the battery and alternator main terminal should be around 13.5 to 14 volts give or take a tenth of a volt or so. Any more and it needs adjustment of the regulator or you will over charge the battery. I would aim for about 13.8 volts. Or a couple of tenths lower if it is a maintenance free battery you cannot top up.

[JJC]

Butec Alternators can be rebuilt with the voltage regulator as part of the alternator. Works great....keep the old blue one where it is for appearance .

JJ

[MarekH]

Similar to what? Generally, if you have a similar problem then you can solve it in a similar way to the way it was solved last time.

It'd probably be best to describe the problem. The regulator is a very simple circuit (already described in another thread) and repair is equally easy.

Once you have read the description, you'll realise that the most common problem, the alternator output remaining at 18v+, is due to its field winding being permanently grounded, either through bad wiring, or because the big transistor in the regulator permanently conducts (keeping the field circuit permanently connected).

kind regards
Marek

[christopher storey]

Oh gosh, not another one - this is about the 4th spammer we have had this week, 2 of them on this thread

[MarekH]

These spammers should at least learn some basic grammar and comprehension.
More profound than what?

I think the strategy being employed is one of having to post a certain number of times before access to messaging is permitted, so if David removes their accounts before this happens, then hopefully we shall remain safe from a potential hack of the forum's messaging system.

[mgcjag]

They are gone now.....Steve

[Ronald Littlewood]

They are gone now.....Steve

Yes I am but auto electrics slightly different to houses , mean while can some one please tell me where the voltage regulator is on a Series 2 1969 FHC. TIA Ron.

[christopher storey]

It is usually a small square black unit, about 2 inches square, positioned in a vertical position under the heater fan box, to the rear of the battery and it may have 4TR embossed on it

[Ronald Littlewood]

Hi Many thanks but the Voltage regulator @ SNG is a small aluminium gadget? Also can you please tell me how to access the fuel level sender?

[mgcjag]

Fuel level sender is in the fuel tank.....the small silver unit is a voltage stabiliser.......Steve

[MarekH]

Ronald,
it's customary to start a new topic when changing the subject of someone else's thread.

The alternator and regulator on the s2 car are totally different to that of the s3.
The fuel sender is common to both, but isn't related to the original topic.
The 10v regulator for the dash instruments behind the drop down dash is also common to both s2 and s3 cars, but isn't the subject of the original thread.

This post is in the s3 section. People who have a s3 car may not know how a s2 car is configured - the two cars are substantially different, so you are more likely to get good answers for s2 questions if you post in the s2 section. Most s2 owners will probably not even have read this, since it is posted onto a thread about Butec regulators, which don't figure at all on their cars.

The knowledgebase section elsewhere on the website has exploded diagrams of your car which hopefully give you the information you need.

kind regards
Marek

[christopher storey]

If you mean the 10v instrument voltage stabiliser ( nothing to do with alternator voltage which this thread was about ) then it is inside the let down instrument panel, usually towards the open end on the right hand side