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TR2/3/3A Tr3 Voltage regulator

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sp53

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Tr3 Voltage regulator. Well I started up my tr3 and the generator light stayed on. I checked the generator and it is putting out. The regulator is off an old parts car that supposedly ran before the gas tank was sugared, but who knows if the light was on. Does anyone have a test I might use before I order a new one? This vehicle has been a ground up frame off restoration, but I think I have all the wires right, so I do not know. Any suggestion would be appreciated.

Steve
 
Had exactly the same problem starting up my TR2 after laying dorment for 37 years (after a "bit" of engine work, of course). After checking my generator, I open the regulator and carefully polished the points with some very fine emery cloth, cleaned with alcohol and tried it again.

She's now charging like a champ. Good luck.
 
From what what I have read on this forum is that about half of the regulators purchased from the big three are defective. I went to this site and had mine redone with modern parts. It is about $80 but you know it will work.
I have had no issues with it.



check out this web site. 1 week turn around. You do send him your old one and he will send it back all new.
https://www.mgaguru.com/mgtech/electric/et232.htm
 
I'm curious, how do you know the generator is "putting out"? The light on the dash essentially compares the generator output voltage to the battery voltage; so it will not be on if the generator is putting out 12v.

In your case, I would start by double-checking the wiring; especially to the 'ignition' lamp on the dash. It does not get grounded, but should have one side connected to the ignition circuit (white wire), and the other side connected to the charging circuit (yellow wire to 'D' terminal on control box). Also double-check that terminal 'D' of the regulator is wired to the big terminal on the generator, and 'F' is wires to the small terminal.

Then try repolarizing the generator. One way is to remove the wire from the 'F' terminal and briefly connect it to 'A' or 'A1' (engine not running). You should get a little bit of a spark.

If that looks OK, use a voltmeter to check the voltage from 'D' to ground with the engine running. If it is nearly zero (less than 1 volt), then either there is a short to ground or the generator is defective. In that case, remove the wire from the large generator terminal and check directly on the terminal (which may require removing an air filter and/or some of the linkage). If it's still less than 1 volt, the generator is bad (perhaps an internal short, or a brush not making contact).

If the voltage at 'D' is around 2-3 volts, the generator is probably not getting field current for some reason. In that case, check the voltage on 'F' which should be the same as 'D'. If not, the control box is defective or very badly misadjusted. If both are around 2-3 volts, then check at the small terminal on the generator. If it is the same, the generator is bad.

Go here and download the "Lucas Generator and Control Box Tests" booklet. It gives a detailed test sequence.
 
Thanks Randall I will try your suggestions when I get home. I checked the generator by looping the two connection on the back of the generator and ran a volt meter from there to ground and had 12 volts @ 1100 rpm
Steve
 
Ok, that's a pretty good sign the generator is working, so no need to repolarize it.

That makes the control box the most likely suspect; so I would probably jump directly to checking voltage at 'F' and 'D'.

Mine started working a whole lot better when I removed the adjustable contact and polished both contacts with a point burnishing tool, then reset the gap per the book.
 
At 1100 rpm's, full-fielded, 12V is not good.
Needs to put out more than that.
I look for 7.5V on a 6-volt generator before I call it "good" when full-fielded.
 
The pages start out blurry but should clear up as it builds and displays the pages (or at least that's what happened when I viewed it). Was it blurry for you after you downloaded it?

Scott
 
Randall - I got a blurry image but then every page became "sharp". All except page 28 !! Was that like that as you received it from LUCAS or did to try to "fix" that page 28 ?
 
There's a color scan of the same manual here (a used copy so some staining and the file is 3MB versus 1MB).

Lucas Generator and Control Box Test (color scan)

Not sure that I see much difference in the text clarity (sorry in my pre-edited post if you saw it I was looking at some other B&W scans I had that were lower resolution).

Scott
 
Don Elliott said:
Randall - I got a blurry image but then every page became "sharp". All except page 28 !! Was that like that as you received it from LUCAS or did to try to "fix" that page 28 ?
Click to expand...
Man, talk about a tough crowd! I not only bought the manual but took the trouble to scan it & post it; now you're going to bust my chops because the Lucas logo on the back cover is a little blurry?
:devilgrin:

Seriously, Don, I can't lay my hands on the original at the moment (might still be on my desk at work), but I believe the blurriness on the back cover is an artifact caused by our monochrome (but automatic page feed) scanner at work. ISTR the original had a nice red background that was only slightly faded with age.

No doubt there was a mode selection that would have rendered the back cover better, but I was more interested in the text and in getting it done in a reasonable length of time.
 
Nice call John B what I did was clean up the contacts and it all worked well. I perhaps have taken too much off because it seems to want to charge too much, but I have never taken the vehicle out on the road yet. I will most likely take Randall’s advice and try setting the caps to specifications. However, after all these years of working on tr3s, I never have tried that. I remember a time when if you purchased a rebuilt generator and did not purchase the regulator with it, they voided the guaranty.
Steve
 
Randall - I was pulling your leg. Most things related to Lucas are (or seem) blurry. Especially that page 28 with their logo on it. I wasn't saying it was your fault. I was saying that it's just one of those normal Lucas things - that even their logo is blurry.
 
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