You can't have proper measurement with stator winding connected. You need to unsolder it and fill the table again. I will then answer to your all other questions.

 

PS

I was confused by the fact you have 2 cars in your profile and the spare alternator from VW added to confusion. So what amperage has the alternator you opened? 90A from Felicia 1.6 with A/C and power steering?

I have borrowed a solderer from my father in law now.

I will start to solder and take proper measurements tonight, there is still daylight and I need to do some other things right now.

You are not the only one confused with the alternator, I was certain it was a 70 amp generator, since the car wasn't fitted with AC.

However, this are the writings on this generator:

441.0.4003-226.6

443 113 516 591

WG6 CZ 14V 90A

Of the diods I thought were in groups of four, one is different, with stripes along the edge (sort of like a coin). While the other 3 are smooth.

This is true of both the positive ones, and the negative ones.

It could be that these "odd one out" are something different, and that there are in fact sets of 3.

It took me a while, but I've managed to identify your alternator. It is a MAGNETON 14V 90A alternator that was fitted on Felicia 1.3 with A/C. See photos below.
 
 
 
That is raising a question right away: did you order the right voltage regulator for a 90A alternator? Part number from ETKA is 004003226JA. The voltage regulator for a 70A alternator is different, part number 115901253B.
 
About how many 'pair' of diodes there are: always there are 3 rectifier diodes for the positive, and 3 rectifier diodes for the negative. All 6 are bulkier than the other diodes (3, not 2). The arrangement of diodes on plates is different from my previous picture only because I thought you drive a Felicia 1.3 with a 70A alternator. But the wiring should be identical.
 

 
Awaiting for the new measurements. For now it looks at least one rectifier diode for positive is shorted.

Edited 13 October, 201312 yr by adurer

Good night Adurer,
I have no AC in my car, it could be that the original alternator broke, and the previous owner replaced it with the 90 amps one?
I'm almost certain I bought the regulator for the 70 amp alternator.

I'm making some pictures and composing a post with measurements, and indeed, we seem to have shorted diods.

*Edit* I now checked the voltage regulators.
The old one has only the markings K6 14V and 58 on it.
The new one reads UR-2315 VR-MP134 M5003368, and on the new voltage regulators box VR-2312, and 198-k with handwriting.
Not at all confusing!

*/Edit*

Edited 13 October, 201312 yr by krrcan

The Stator was abit wierd, it had 12 cables comming out of it, in pairs of 2. 6 pairs in total.

Can we consider this a 6 coil alternator, or is it 3 doublecoils?

This is what the diod bridges look like:


In this image I have indicated what groups I have.


This is my try for a diagram of this alternator:


The values I measured, from column measured to row.

\   B+   D+  B-

A 510 545 inf

B   0   510 inf

C 498 508 inf

\    A      B     C
B+ inf    0     inf

D+ inf   inf    inf

B-  520 503 508

\   B+   B-
X 514 inf

\     X

B+ inf

B- 515

 

That I measure 0, from B to B+, in both directions indicates that this diod is shortend.
All other diods seem to be OK.

The old one has only the markings K6 14V and 58 on it.

The new one reads UR-2315 VR-MP134 M5003368, and on the new voltage regulators box VR-2312, and 198-k with handwriting.

Not at all confusing!

Yeah, it's the one in here made by Mobiletron Taiwan. Don't know how good will handle a 90A alternator in terms of correct charging current, but will definitely not handle loads over 70A.

Edited 14 October, 201312 yr by adurer

The alternator you have has (surprisingly to me) a so called Y-type (or star) stator connection (see illustration below). The previous schematic I posted has a Delta-type (or triangle) stator connection. The output current with a Y-type stator connection is constant over a broad alternator speed range, but it produces 42% less current than an identical alternator having the stator connected as Delta. The Delta-connected alternator, however, produces lower current at low speed and must be operated at high speed to produce its maximum output. 

 

Congratulations for schematics, your persistence paid off. You have indeed one diode shorted. You have to decide now if you get it from your other car, your other alternator, as a single part or as a block. Let us know when all is back in order.

I would have thought a 70amp regulator would be ok in this situation, as the car hasnt got A/C it wont be trying to pull the extra ampage from the alternator; just remember it has the 70amp version fitted if you ever try and use it on an A/C fitted car.

 

However I will wait for the final judgement from the expert :-)

I'm not confident that I would be able to replace a single diod, they seem to be pretty stuck in place.
It's possible that I could be able to solder on a new diode bridge on this stator though.

Not sure I will ever be able to put this humpy dumpy back together in any case, but it wouldn't hurt to try, if a diode bridge isn't costly.
Best thing with this venture is the learning.

Can these be bought, and if so what number do they have?

 

 

Regarding the 70amp regulator in the 90 amp alternator:

I can simply swap back to the old voltage regulator, or I could just take it easy with the electronics.

...Best thing with this venture is the learning.

...

 

I agree.  A very enjoyable and educational thread to read. 

Big thanks to yourself for having the patience and persistence to really dig down to understand this problem (and share that with all of us), and to adurer for obvious reasons.

I would have thought a 70amp regulator would be ok in this situation, as the car hasnt got A/C it wont be trying to pull the extra ampage from the alternator; just remember it has the 70amp version fitted if you ever try and use it on an A/C fitted car.

Just in terms of current drawn by the existing accessories, yes, the 70A voltage regulator would suffice. But adding extra loads thinking it's a 90A alternator after all... that would be a bad idea. It is this scenario I had in mind. But the real problem is the battery charging current curve. Let's not forget the voltage regulator senses the total current drawn by the accessories and adjusts the current passing through rotor, thus adjusting the magnetic field. The charging curve is tailored to a certain type of stator coils and their type of connection.

 

Regarding the 70amp regulator in the 90 amp alternator:

I can simply swap back to the old voltage regulator, or I could just take it easy with the electronics.

Assuming the old voltage regulator is good (sometimes things break in chain) it would be the wisest decision to put it back.

 

Not sure I will ever be able to put this humpy dumpy back together in any case, but it wouldn't hurt to try, if a diode bridge isn't costly.

Best thing with this venture is the learning.

Can these be bought, and if so what number do they have?

The block of diodes can be purchased separately. Part number is 004003226S.

 

In the end, I'd like to say there are a few lessons to learn from this topic:

- diagnosing an issue can be a winding road or a straight hit; using photos or a video to show the malfunction does make the difference.

- you don't change expensive parts before finding the evidence of malfunction

- the process of repairing can be explained in words, or using photos; depending of my free time, I prefer the latter

- you never know everything; those thinking otherwise haven't read what is written in small letters

- you may never know what you're skilled at because you didn't try

- trying to repair things can be a rewarding experience; nothing compares to that feeling of accomplishment (except for sex, getting married or being a dad... ehem)

Edited 14 October, 201312 yr by adurer

Bit late in the day ,but might be of future help . On the older type of meter with a moving needle ,on a medium resistance ,a diode will test close to S/C with leads connected one way ,and O/C with leads reversed . ( S/C = max deflection,O/C =no deflection). Most modern DVM  have a doide function ,and on most diodes you will get spmewhere like 1.4 withleads one way and infinity with leads reversed . Without a diode test function , I'd be reluctant to trust DVM  meter readings from years of experience . In fact in the older days ,I always had two meters on the bench- a moving coil one for semi conductor tests and a DVM for volts . if you look at the diode symbol , curent fdlows in one direction -from the wide bit of body to the narrow ( BIT LIKE A ONE WAY STREET SIGN ) . if you look at the diagram #32, item 4 shows the positive diodes. rectifying the AC from the stator to B+.

 

Just one other thing- when soldering in a diode - ( silicone ones are not too sensitive to heat ) - if you're not too hotwith a soldering iron - use some form of heat shunt on the diode. Although most solder has flux in the core, I tend to dip my solder in plumbers flux, and add some to the componant to speed things up . You can always wash off excess flux,

 

Just bits of hopefully usefull info from an old electronics pro .

I usually hold the stuff in place with needle point pliers - which then double up as the heat sink.

krrcan did just fine so far, he measured correctly, he presented his measurements in a clever table, he even back engineered the alternator schematic. So he's far from not knowing "the one way street sign" on a diode or needing help to measure or solder. The guy who might have problems with his newly acquired 'voltmeter' is in another topic covered by you.

Edited 19 October, 201312 yr by TeflonTom

if anyone feels the need to share his technical knowledge about repairing cars in general, and Skoda classics in particular, he/she is more than welcome to write a guide in the special section titled Classic Technical Guides. We need lots of guides in there. The only condition is to be accurate, because disinformation is worse than misinformation.

Edited 19 October, 201312 yr by TeflonTom

Right listen up, this thread has been tidied up, we do not operate a public slanging contest, nor do we criticise anybody's use of spelling or punctuation, there is a lot of pure gold content in this thread which enriches our experience of the classic models zone the likes of which I've not seen here before, anybody who feels the need to argue pointless semantics and feels the need to poke insults around I suggest you try the seat cupra net forum, you'll fit right in there..

This might not make any of you wiser, but I had the same issue on an identical car as krrcan 2½ years back (even the same alternator). Battery indicator flared up like an angry christmas tree since it stopped regulating and voltage went up to 18-20 V with rpms increasing. Not good for battery, to say the least.

After changing the regulator I have been driving over 10000 km, with the battery light shining, just like krrcan describes. I haven't done anything about it since it is charging (and stopped overcharging).

My question is if driving around with a faulty generator might be negative in the long run? It is indeed charging and giving correct output (I did measure the voltage for obvious reasons).

I would like to fix this like krrcan did just to stop that anoying read light, but do not really prioritize it since the car is functioning excellent.

I am also very surprised that only the battery got fried by 20 V charging.

This surely is tank technology...

My question is if driving around with a faulty generator might be negative in the long run? It is indeed charging and giving correct output (I did measure the voltage for obvious reasons).

If you have a simmilar issue to what I had, the alternator will be putting out abit too low voltage.

But appart from that, from what I think I have learned now... the current that it delivers will be of inferior quality.

It will be more fragmented, and less smooth.

I do not know if this is likely to cause some long term problems.

If anything, I imagine that bulbs and other electronical devices will see increased wearage and shorter lifetime.

Not 100% sure of anything though!

The key word is "voltage ripple". You can see and measure it with an oscilloscope, most DMMs can't catch only the AC component but rather display an elusive and incorrect average DC voltage. For that purpose I find the video below titled Alternator Diode Testing quite informative in terms of symptoms, diagnose, effects, and repair. If in a hurry, jump to 2:34. But I would recommend watching it in full.

 

Edited 26 October, 201312 yr by adurer