Why should my generator warning light flicker when I rev my DEXTA?

[Mervyn Spencer]

Hi Folk,
After flashing my generator I was able to get the generator light to extinguish, but when I increase the engine speed close to 2000 rpm the generator light starts to flicker. Anyone had that experience before? I have taken the generator off and will get an auto electrician to test it for me this week.
Mervyn.

[Billy26F5]

Might be a regulator issue, run the test and see how it performs, the manual covers it in detail for all types used (If it's a sealed RB 108 the setting of the gaps can still be done by carefully bending the tabs back to remove the cover, as JCB instructed, the settings are the same as the RB 106/2, but not the RB106/1 originally used with Major's, which might have been fitted by mistake). Probably also worth checking connections and perhaps the brushes too.
http://www.smallholderservices.co.uk/si ... electrical
Sandy

[Mervyn Spencer]

Thanks for your response and link Sandy. Unfortunately the Dexta is at the club premises which is 55km from my home, so what I want to do initially is to take my generator which I brought home on Saturday to the local auto electrician to test. If it tests okay then I can follow your suggestion as per the workshop manual article you kindly sent me. Hold thumbs its in the generator.
Mervyn.

[Mervyn Spencer]

Generator tested okay, now need to venture further with the regulator, I will need to check all my connection also.
Mervyn.

[Billy26F5]

I don't think it's a connection but always worth checking. A good voltmeter is a must for this.
Sandy

[Mervyn Spencer]

Just a follow up on my generator warning light flickering. I removed the control box/regulator from the tractor and opened it up but found nothing obviously wrong with it. However I did connect the control box up without the cover and accidently touched the voltage regulator relay which burnt the generator warning light cable down to the connection under the fuel tank, which I have since repaired . This last weekend I went out to the tractor again and have come to a conclusion that the problem maybe that I don't have a gasket under my aluminum cover that secures the warning lights which results to the lamp holder shorting to earth. To import a gasket is rather expensive considering the currency exchange rate between us and overseas, so I have attempted to make one myself. I have noticed that the gaskets available from overseas have a recess where the lamps and temp gauge would sit snugly. I would appreciate if some kind member would have any idea what the dimensions of those holes and recesses would be. Unfortunately I have left my lamp fittings at the club which is 50km away .

[Billy26F5]

Unfortunately I don't have those measurements as I've never taken Davie's dash off, but as far as I know if you get it to fit the lights it should be ok. Beware of repro parts as usual. As for the regulator if you didn't check the gaps and check the electrical settings there is no way you can be sure everything is ok. When I looked at Super Billy's regulator it looked fine until the feeler gauge was used, the clearances were enormous and then the electrical settings were wrong too. Always set the electrical settings with terminal A disconnected.
Sandy

[Mervyn Spencer]

Thanks for your input Sandy, I will check those gaps after I have resolved my warning light issues. I did find some measurements of the lamp fitting but I must first check those measurements with my lamps before preparing my gasket. I will end this post now.
Mervyn.

[Jerry Coles]

Hi Mervyn
I suspect that when you rev your tractor the generator output (relevant to the engine speed) is going hi. If the voltage output of the generator goes too high it will cause the Battery to Gas (give off Hydrogen gas) when over charging which is damaging to the battery. So one of the functions of the regulator is to reduce the generator output at high revs to prevent this. So your lamp flickering is a sign that the regulator is doing it's job and preventing the battery from over charging.
Regarding your lights and ground problems, the lamp holders should not be earthed. The Ignition warning light has the battery voltage on one side and the generator output on the other. As the generator increases in output, it's voltage equals or goes just above the battery voltage and the light extinguishes. I have put in a link to the Agriline - Dexta- Electrical section of the catalogue, as you can see there are two terminals or leads to the lamp holder. Lamps with twin contacts on the base should be used.
With your Exchange rate problems I can only suggest you visit an auto dealer that may stock older car spares where you might strike lucky or if any classic car owners out in SA might help too.
https://agrilineproducts.com/ford-fords ... electrical
This is informative reading too!
https://www.mg-cars.org.uk/imgytr/pdf/lucascourse5.pdf
Hope this helps )

[Jerry Coles]

And in simpler terms:
https://www.matchlessclueless.com/elect ... regulator/
Note this is probably for 6v RB108 regulators but the principles of operation are the same!
Jerry

[Billy26F5]

The Ford manual already covers this, there's a later version of the Lucas manual covering the RB108 too https://traction-owners.co.uk/wp-conten ... ontrol.pdf
Until everything is properly set it can't be confirmed that it's not an adjustment issue, I suspect the voltage could be out of adjustment. Dirty contacts can also cause such issues. A good service should be all that's needed.
Sandy

[Mervyn Spencer]

Gentlemen, thank you very much for the links on how the generator and control box work in conjunction in our vehicles. For once I can understand why my generator warning lamp has mis behaved. I foolishly was under the impression that the yellow wire attached to the lamp holder was an earth wire, not realizing it actually becomes a positive from the armature.
Jerry, you mention a two filament lamp that should be used which I find difficult to understand when you have such a low watt lamp of 2.2w and so tiny. The loom and lamp fittings that I purchased form Ireland which had the rubber shroud around the lamp holders and no lamps but included the lenses, happen to require a single filament globe. I actually Googled which lamps I would require and the 2.2w lamps were recommended, which I also had to import Auto Sparks.
Just to recap, in February 2022 I had my tractor wired up by a local auto electrician who fitted the warning lights for me and all was well for a couple of weeks. The next time that I started the tractor I noticed that the generator light remained on and in frustration having attempted on numerous times to find the problem I ripped the rubber shrouds off the lamps which were now starting to tear has now made things worse.
Short of ordering another warning light loom and rubber gasket I still fail to see how I can avoid earthing the gen lamp by the screws that secure the aluminum cover over the chrome around the lens which are attached to the lamp holders. Does that rubber ring similar to a balloon have to be above the aluminum cover?
Sorry about the rant but this issue is really driving me insane
Mervyn.

[Billy26F5]

The bulbs are part no. 100E-13466B, and are similar to a Lucas 643 or 288 bulb. The rubber is between the lights and temp gauge and the chromed dash, and as I see it the outer light housings are insulated from the bayonet holder (in theory). Maybe you need to remove the housing and look inside, maybe you'll find the true issue in there, although I would check the regulator first.
Sandy

[Mervyn Spencer]

Hi Sandy, thank you for the globe codes I will make a note for future. Fortunately I kept my original warning lamp holders and was able to prove your theory on the lens clip being insulated from the outer lamp body. I will now have to find some heat shrink to shrink on to my bear holders to prevent shorting.
Mervyn.

[Mervyn Spencer]

Problem solved with some skill and initiative .
Thank you to all previous suggestions folk much appreciated.
Mervyn.