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90 Amp Generator on 109 FFR Land Rover


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I found I had got this picture which might help. I am not sure if I took it or whether it was sent to me, but I certainly labelled it. If it is someone else's picture I hope they won't mind as it is now someone else's turn to be helped (I hope).

 

Jimmy don't worry about the feed holes to the shunt box, there was vast variation as to what went through a particular hole on the various configurations installed.

 

Shunt box labels.jpg

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Have you changed the fuse? It looks different & the retaining screws are in a different position. The fuse is just in the radio battery circuit.

 

 

Clive, During my investigation, I did some checkes and I did change the fuse as it was blown off.

It is only after the second reading of your document that I realised it was pointless......

(I had a lot of hoe in first instance !!!)

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TClive the picture will surelly be of help, thanks a lot.

Looking at it, I think I am too far from that. only 2 leads to put back correctly.

And this one looks much more in line with your diagram.

 

Will try to do that this evening.

 

Next step will be the new main harness that is confirmed on its way (it's a 17 Ft long, so I guess it's ok).

In case it is not hte good one, I found some supplier in france that have new and second hand ones, so I still have a solution in case.

 

hopefully I am touching the solution.

 

Cheers

 

Jimmy

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Just check the U & V pin at generator level as mentionned in previous threads.

I had made this check weeks a go and already had no reading, so checked the carbon brusches and discovered that one of the maintaining spring was broken.

All this was changed and I must admit that I didn't recheck after changing the brisches and the spring.

I took for granted that this problem was resolved.

I was more concentrating on the voltage delivered between the chokes.....

 

Anyway, checking agin this morning I have no reading between U & V Pins !!!!

 

Do you recommend I check again the brushes ?? And dismantle the cover again ?

Could it be another problem ?

 

This is a surprise to me.

 

Jimmy

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Jimmy if you have no reading at U-V directly on the generator then you have no option but to dismantle the brush assembly. Rotate the shaft & check again if there is a reading but with a broken spring it is unlikely.

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Clive,

 

The spring was changed at the same time I changed the brushes.

But I may have done something wrong.

 

Stupid question may be but I can chack the resistance between U & V before re-assambling everything ?

Will do that tonight or tomorrow morning.

 

Jimmy

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Yes I would check the resistance of the field winding before you reassemble the brushes, to do this put the ends of your resistance tester across the slip rings (Item 24 on pages 20/21) & should be about 15 ohms I think.

 

These are the two rings next to each other that each brush rubs against. When you have reassembled the brushes & springs make sure the brushes do exert pressure on the rings & are free to move against the spring tension.

 

Also make sure the brushes are aligned correctly & that a brush can only contact its own slip ring without touching the other ring. Make sure that the edges of the slip rings are clean & free of conducting dust from the wear of the old brushes.

 

Then check that the U-V resistance is correct on all rotations of the shaft, then replace the end cover.

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  • 2 weeks later...

Hi,

 

so i made some new checks and must admit I am now a bit confused.

weeks ago I had something like 24,5 V between the chokes in the control panel as an output from the generator.

But discovered that I had a spring broken at the brush level when measuring the resistance between pin U & V.

I changed the brushes, had again 24,5 V between the chokes.

Last week I rechecked the resistance between pin U & V as mentioned above and noticed no reading.

checked today the brushes, they are ok. Cleaned the split ring. They look ok to me.

i still have no reading on the meter, even if at a point of time it went up to above 170 ohms....

after cleaning I had 32, then 17 and then nothing again.

when checking the output at the chokes I now have 1 V.......

I checked it with 2 different harness.....

 

The 24V output I had was on the former control panel box.....

i just changed it recently thinking it could be the reason of the fault.....

i would probably need to check again with the former box ??

 

 

Anyway, I am really suspecting now a fault at the generator level.....

 

i have 2 generator control panel, 2 mais harness..... and it still doesn't charge the batteries....

 

If brushes are ok and split ring as well, it means that the generator is faulty no ?

 

cheers

 

Jimmy

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Jimmy before worrying about whether the new generator panel & cable harness are defective you need to get a sensible reading on the field winding (ie U-V) this is fundamental to everything else.

 

Open up the cover to the brushes & remove them. Put your ohmmeter across the slip rings. Unless you get a sensible reading here everything else will not work. If there is no sensible reading & it is open circuit the field winding is damaged. It is unlikely to be "burnt out" excess heat might burnt the insulating varnish & give a lower than expected reading.

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Ok Clive, will check the reading at the slip ring.

wich I have not done yet.

Only at the pin level.

And I can recall that the pin U or V was shaking a bit and the reading (when I had it) was moving from a figure to another.

 

I may have to look at the connector on the generator at a later stage depending on the findings on the slip ring.

 

Will try to do that today.

 

cheers

 

jimmy

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Hi,

 

Findings of the day :

 

Resistance at the slip ring level : around 15,2 and 15,5 depending the contact point.

When I put back the brush assembly and mesure at the little wire connectors or the screw I have around 17,8 and 19,8

And when I mesure at the U & V pins I have above 21 to 24......

 

I had no reading at pin level 2 days ago......

 

I guess the good news is that I have the correct resistance at the slip ring level !

 

The brushes were changed recently and their length remains within tolerance.

 

I did clean the rings but may be not enough ?

 

What else should I do from here ? As surely I do not have the good required resistance at pin level.

 

Thanks for the advice.

 

Cheers

 

Jimmy

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Jimmy that sounds like good progress, don't worry about an ohm here & there. It is also difficult to accurately measure low resistances & although a digital meter can give readings to several decimal places, this detail of reading can be misleading because the test prod tip has a small surface area & will not make such a reliable contact as a pin entering its connector.

 

I think it is now time to run it & see what voltage you are getting between the two chokes.

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I think I made some good progress today :

 

Whne reassembling the brush assembly, I noticed that one was not really in the good side.

The little cable for connection was kind of blocking the spring pressure.

So I put it back ans I think it changed the pressure that was exercised on the e brush.

I then reassemble everything and guess what : I had light at the charging light and the ammeters are moving !!!!

So I measured the voltage at choke level and had 28,5 to 29 V and around 27,4 at batteries level: around almost 2 V more than when checking the batteries alone.

But : as a there is always a but !

When I start the car, the needle of ammeter goes significantly to the right showing that it is charging, but comes back to almost 0 almost immediately.

then if I run the engine at a higher speed, it doesn't move anymore, but remains higher than 0 levé,.....

 

should the the needle of the ammeter have a movement link to the level of acceleration of the engine or not ?

is it that as far as it looks like charging it is ok ?

 

I would like to know more about the behaviour I should expect from the ammeter.

same from the voltage at batteries level. It looks like I have a permaent Superior voltage at batteries level when the engine runs, idepently form engine sped.....

 

 

thanks for stour advises

 

 

heers

 

jimmy

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Jimmy well done you have sorted the problem due to your diligence & determination. You must be feeling very pleased.

 

If the ammeter swings to the right then back to '0' it means the batteries are not accepting any more charge ie the batteries are fully charged! :D

 

Now is the time to test the other harness & generator panel, so that you can be certain you have spares that are in working order.

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PS Sorry I meant say that the reason that high revving does not produce extra voltage is that the voltage regulator is functioning correctly :D

 

As you increase engine speed the output voltage tries to increase but the voltage regulator senses this so it reduces the voltage it sends to the field winding via U-V. This reduces the magnetic field so there is less output voltage generated.

 

The reason to rev a bit when testing for output is that at idle & low revs there may not be enough output for the generator to achieve its design output.

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Clive,

 

Well noted and I will do the testing to see if I do have spares in working condition.

Meanwhile I really want to thank you so much for your support !!!

Very honestly I think that I would have gave up since long if not feeling pushed by you on my research.

 

I really learnt that patience is a key, and step by step approach a good solution, if not the only one.

 

Your documentation and knowledge is a real bible and you can be sure that I will strongly advertise it on the French Forum I participate for my friends that have old FFR Series or Light.

 

If not that far I would have come to pay a beer !!!!

 

Thanks again for all the help !!!

 

Jimmy

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Jimmy that is kind of you. You learn a lot when you have to sort out the problem yourself, far more than getting a professional to fix it for you. Although many professionals are trained for commercial installations & have no knowledge of the intricacies of old military systems.

 

A logical approach is the key & not to assume anything works unless you have proved that it does. There is an old medical saying "No treatment without a diagnosis" which holds true for vehicle electrics. Often people replace things without knowing whether the replacement items are themselves in working order & that can just complicate matters further.

 

By all means let your friends see the articles, but with your experience you are now an expert on field windings, carbon brushes & slip-rings!

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