Hi Jake,

I was not going to post this until Chris had proof read it and gave it the thumbs up, however in the light of your continued problem (no pun intended) it might help you understand how the Dynamo works.
I was on the forum trying to contact Chris when I saw your message.
Please note that this document has got a health warning that it has not been proof read yet so might contain errors (my experience is mostly with Lucas electrical equipment) although I am a Chartered Electrical Engineer with a fair bit of experience on car/motor bike electrics.
Once Chris has given it the OK, I'll post it with the Alternator version and a document on general electric theory and problem solving.
Feedback on the document would be greatly appreciated.
Best of luck
Richard

Richard,

Have to say you have done great job! It's nice that there are people like you .
I like the guide because you have wrote it very clearly, every little detail. Even I understanded all the measurement how to make them .
I think I will do some tests today after work.

I will report you later today or tomorrow for the results!

Thanks again!! :worship:

JakeF said:

Richard,

Have to say you have done great job!

Click to expand...

Richard,

I need say no more except 'good one, thanks'.

Chris

Hi,

Got everything measured.

Test 1
-New battery, fine.
Test 2
-Fan belt ok
Test 3
-Dynamo earth, voltmeter gave 0.2-0.4 ohms
Test 4
-Dynamo output test. Got only 0.5-1 volts. And I believe when I got the 1V the rews was more near 2000rpm. This the problem??
Test 5
-Field coil test, got ~8.5 ohms
Test 6
-Leads new and ok
Test 7
-Measured from the control box no 51 and got 10-12 volts at ~1500rpm. If I accelerated more the Volts rised?

So, is the problem the test no: 4? The problems are just at the low rews!
I unmounted the dynamo and will send it back to where I bought it.

Could you Richard give your opinion, is it the armature or brushes.
Hope i finally find the problem!

And i measured from the battery at idle speed, no charging. Accelerated to ~2000-2200 rpm and charging started and the light went off.

Hi Jake,
the reading you are getting from Test no 4 could be OK. It proves that the Output coils, commutator and brushes are doing their job.
If the brushes/commutator are faulty you usualy get either no output volts or a fluctuating reading from the output terminal (51). This usually manifests itself with the ignition light flickering as you drive along.
Because the Field coils are disconnected at Test No 4, the only magnetic force providing an output voltage is the magnetic field provided by the metal in the field coils, which is fairly low compared to the field produced when the Field coils are enrgised via the control box. Did you polarise the new dynamo by "Flashing" terminal 67 (Field Coil) as described in the document.
Unfortunately I don't have a Fiat and Matthews is an Alternator equipped 650 so I can't do any comparative testing.
Dynamos do have the unfortunate characteristic of giving low output voltages at low speeds.
The best way forward is if someone else on the Forum with a similarly spec'd car could repeat the tests to compare the readings to identify any mismatch with your Dynamo. The fact that it is reconned means that hopefully it would have been tested before being shipped out.
Richard

MATTSDAD said:

Did you polarise the new dynamo by "Flashing" terminal 67 (Field Coil) as described in the document.

Click to expand...

Jake, make sure you have done this. Then re-run test #4. You should also re-read the document at the link I previously provided. It also reviews generator testing and how to polarize the generator.
http://nls.net/mp/volks/htm/gen.htm
John

Jake,

Those results may all be normal. As others have said, generators (dynamos) don't have much output voltage until the revs rise a bit, in fact, the performance curves (usually current vs rpm but can plot voltage vs rpm) usually start at about 1500-2000rpm because prior to that there is nothing much to measure.

On the other hand, alternators (AC) begin to generate output from very low rpm which is why the warning light on an engine equipped with an alternator goes out after engine start and stays out even at idle. Alternators can also be built smaller for a given power output, run cooler at greater power outputs, can produce higher outputs at lower revs, are usually somewhat simpler in construction etc. This is why they are so popular on modern cars that demand a high current to run all the electrical gear.

Since you have now removed it from the car again and are getting it checked, let us know the results. I can't help much (except with reassurance) as I converted my car over to an alternator when I rebuilt the engine.

Chris

Thanks. Yes I did polarize the generator also like Richard and John have linked!
I think I will send it back for proper checking because at idle speed it wont charge the battery and this it what I am worried about. Maybe I concern a alternator, I'm starting to give up
I also checked the cable+ from battery to starter, same Volt reading as battery, so should also be ok.
BTW, only thing which I did not check was the green wire from regulator to the warning light and the red wire from regulator to ingnition. Sounds that these ones could not be the problem. If I measure with multimeter is a cable cracked/earthed how it is done?

The only weird thing is that after the engine rebuild this problem occured also with the old generator. Could it be just bad luck that I have 2 faulty generators, or is there something else?
Everything is checked and is right!

Thanks again for everyone.

Found one finnish old mercedes benz site and people have had same problems. Charges at high rpms but not at idle. They had found the problem on a intake air heating resistance which took too much power! This one off and the volts rised at idle.

Could a faulty/wrong ingnition coil cause this, because I changed this one(cheapest coil).
http://webshop.fiat500126.com/index...nfo/6578-1-ignition_coil_magneti_marelli.html
I also have fitted the 123 ignition but dont believe this is the problem.

How can I find if something "eats" energy, I mean that with idle speed how many amps should the multimeter show in normal conditions?
I dont know but now I have a feeling that the problem is something like this...

Sorry about so many questions, hope these helps other people if they have similar issuses

JakeF said:

I think I will send it back for proper checking because at idle speed it wont charge the battery

Click to expand...

I must admit that I though generators (= dynamos) did not charge at idle speeds (800-1200rpm). This is normal and why the warning light comes on when the engine is idling.

Yet another reason to convert to an alternator

Chris

Bambino said:

I must admit that I though generators (= dynamos) did not charge at idle speeds (800-1200rpm). This is normal and why the warning light comes on when the engine is idling.

Yet another reason to convert to an alternator

Chris

Click to expand...

Butbut...It did not have these kind of problems earlier dont want to give up yet!
I dont know should a dc dynamo charge at idle speed but why is the bulp on now and previously not?
I have to check for sure the generator light and the wire and also the ignition coil and battery earth. If these will not help I I will try to change a alternator :bang:

JakeF said:

Butbut...It did not have these kind of problems earlier dont want to give up yet!

Click to expand...

That I can't explain

As someone once said - 'a problem worthy of attack proves its worth by fighting back'. Might have been Einstein.

Keep chipping away at it.

Chris

Bambino said:

That I can't explain

As someone once said - 'a problem worthy of attack proves its worth by fighting back'. Might have been Einstein.

Keep chipping away at it.

Chris

Click to expand...

Yep, thats true!
I will check tomorrow the wires.
Can I test straight from the battery positive if it affects the charging(if the ignition initial energisation wire is broken etc). I mean, a jumper wire from battery+ to the regulator 51?

Hi,
Wires sorted out. No difference. I also bought a digital rpm meter to get the proper numbers(40€, its a handy tool btw).

This is what I did yesterday:

-I made a new green wire from ignition lamp to regulator, no difference.
-The wires from generator to regulator is new.
-Measured the fuse box red wires, all got the same volts as the battery.
-The battery - cable is also measured at its ok(in ground).
-Touched with a cable from battery + the generator terminal 67. Lamp went off.

So no everyhing has tested, It has to be the generator.
I spent some quality time yesterday with my dad at the garage and measured again the generator.

With my new rpm meter at 1500-1600rpms:

-With a wire between the generator terminals the generator gave only 6-8 volts?
That is half less than Mr.Haynes says at manual?
-Same result measured from regulator terminal 51

So I got not enough volts to load the battery at low rpms and turning the ignition light off.
The new dynamo has quarantee and I will send it back. They promised to send a new one if its faulty(to me it is)

Chris, Is it a big job to change a alternator to my 110F block? Is it bolt on and some wiring+regulator?

Jake,

Sorry to hear that your travails continue.

I've not actually mounted an alternator to a 110 engine, what I did do however is rebuild and install a 126 engine which already was equipped with an alternator.

I believe that the mount is slightly different but I don't know for sure. The wiring conversion is quite straight forward.

Chris

Bad luck for me again!
Look at the video what kind of rebuilded/checked dynamo a got from Axel Gerstl!! Cant believe this kind of things happens.

http://img43.imageshack.us/img43/1035/50atrvjwodxpyutyccqwwy.mp4

The rotor shaft moves back and forth inside the bearings and when I turn the shaft the bearing does not turn. I mean the clearence between those are too big so only the rotor turns! + the belt side woodroff key slot is in quite bad condition!

I emailed them about this hope they will understand. I have nothing bad(yet) to say about the company, good service this far with this problem. I have already once shipped(paid) a faulty dynamo back and now they have sent me a crappy part. Do they not check the parts before sending them out?
This is the answer which I got when I ordered the first dynamo and asked about it

"thank you for your email.
Great!

Jake,

I just had a look at my rebuilt generator and I have virtually no axial play. You may be getting close to solving your problem.

Chris

Bambino said:

Jake,

I just had a look at my rebuilt generator and I have virtually no axial play. You may be getting close to solving your problem.

Chris

Click to expand...

Chris,

This one is the second one which they have sent me. I sent the first one back which did not produce enough volts at 1800-2000 rpm/min.

Now, this second one is quite badly worn. When a shaft is supported by two bearings like this one there should not definately be any axial play. I believe the shaft is quite bad worn-->too much clearance.
Still wondering that do they not check the parts before sending them out to paying customers! :bang:

Jake,

are you getting the impression that he is not going to help you? Perhaps you could include a link to this thread when you send him your next email? Vendors always like free advertising.............

Joe R