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Discussion Starter · #1 ·
Evening,
I can see a similar thread with alternator issues just yesterday, but mine is different (I think) and not earth connections Battery or Alternator? Help with diagnostic test...

After months of perfect running the generator dash light came on at the end of a long run. Not flickering, just Full on with engine running. Checked fan belt, all good there.

I ran a generator test and it’s sending a healthy voltage to the Regulator
(60-65 volts healthy when revved). Wiring all looks fine (professional rewire couple of years ago). Tested the green wire out of the Regulator to the dash and was showing zero when engine running, so figured new Reg needed.

fitted a nice replacement picked up at Slough Swapmeet and fitted it. Dash light on with first click, off with engine running. Bingo…

…3 miles down the road and dash light flicks on/off couple of times. Then full on. Back to before.
Am I frying my regulators? I can’t see any damage on the one removed (but not taken it apart, it was a Mexican old style). Is 60-65 volts way too much from the Generator? The YouTube vid said you want to see min 30-35 but nothing on the top end of the range. voltage.https://www.google.co.uk/search?q=ve+bus+generator+test&ie=UTF-8&oe=UTF-8&hl=en-gb&client=safari#fpstate=ive&vld=cid:8d73c05e,vid:JUeeuDrIKVQ,st:0

If not that, what do I look at next? Feel like I’ve been through the system (but not exactly ‘cos I’m no auto electrician!)

thanks!
M
 

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What vehicle is this on ?
Do you have an Alternator, with internal regulator or a different arrangement ?
60-65 VOLTS doesn't sound right
 

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Discussion Starter · #3 ·
It’s a ‘69 Beetle with a 1300tp engine. Stock dynamo/generator (not alternator), regulator under the back seat. It’s pretty much stock but everything’s been changed or replaced in last 10 years.
 

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It’s a ‘69 Beetle with a 1300tp engine. Stock dynamo/generator (not alternator), regulator under the back seat. It’s pretty much stock but everything’s been changed or replaced in last 10 years.
The original type regulator (under the back seat), has a resistance winding on the back, it is exposed (to keep it cool), but easily damaged. If the resistance wire has broken, the dash light will stay on.
Inside the regulator, the contacts can arc and stick together, this will also cause the dash light to come on. You can open the Regulator and clean the contacts, and it may work for a while. At least you have an old spare regulator to open and try.
 
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That voltage sounds far too high and would also explain why the regulators have failed. The regulator can only regulate the generator within a certain voltage range. If too much voltage is produced then try as the regulator might it can't bring the voltage down and as it wasn't designed for voltage that high it dies.
Sounds like there may be a short in one of the windings that has reduced the number of turns in that winding as this changes the relationship in the voltages produced.
 

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Discussion Starter · #6 ·
Thanks for your replies, I’m going to check the Genny again this weekend to double check the output. It was surprising how high it was but really I was just looking for it to be charging well. It sounds like it could be blowing the Regulators, which is why I got a short run before no2 failed. If it is a short in the windings is a new generator the easiest fix?
 

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Thanks for your replies, I’m going to check the Genny again this weekend to double check the output. It was surprising how high it was but really I was just looking for it to be charging well. It sounds like it could be blowing the Regulators, which is why I got a short run before no2 failed. If it is a short in the windings is a new generator the easiest fix?
a short in the windings will mean a new Genny and if that's the case you may as well upgrade to an alternator. If you have VW buddies then see if you can borrow a known good genny to see if this cures the problem.
 
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