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Re: Dnepr mt11 alternator woes

Posted: Wed Jul 17, 2019 4:04 am
by Claus
If things are right, the key can be pressed in with little force (in a vice) or with very gentle blows of a small hammer.
If the key falls into the slot itself, it has to be raplaced (and the slot has to be inspected for wear)

Re: Dnepr mt11 alternator woes

Posted: Wed Jul 17, 2019 10:04 am
by brianural
Claus wrote:
Mon Jul 15, 2019 2:42 pm
brianural wrote:
Mon Jul 15, 2019 1:23 pm
Not familiar with the manual your linked. I recently had issues with my MT11, thought is was the 424 gen, ended up being the 33.3702 rectifier.
Sorry brianural, 33.3702 is the electronic Ural regulator from late 80ies or early 90ies . The rectifier is built in the alternator. This regulator leaves the wave line connector on the alternator empty and operates the generator lamp itself (like a voltmeter, it switches on or off the light without reason sometimes). This regulator can be swapped by Beru reglulator GER 024 https://www.ebay.com/sch/i.html?_from=R ... 4&_sacat=0 , but the generator light would not work lack of pre-exciting diodes in the rectifier. (I used that for ages on my Ural and mounted a volt meter to the handlebar. So I always knew what was on.)

The Beru regulator is connected like this: DF (field) is connected to "shunt" (E lying on it´s back), D- is connected to negative ground and D+ is connected to switched power (it´s hot once the key is turned on).
If you change from solid state regulator to 33.3702 or Beru, let the wave line connector empty on the alternator, the + and the field connector are connected the same way as with the solid state regulator

Claus, I do know that its a voltage regulator, I used the OPs use of rectifier so as to not cause confusion. Hindsight, I probably should have used VR term.

Re: Dnepr mt11 alternator woes

Posted: Wed Jul 17, 2019 12:32 pm
by Claus
Ah, I understand.

Re: Dnepr mt11 alternator woes

Posted: Wed Jul 17, 2019 12:52 pm
by Dneprswede
Got My alternator separated today. One of the carbon brushes was split in half and floating around in there. That should be the culprit. I will order a new set and give it a try. I'll let you know the end results.


Thx for helping out!

Re: Dnepr mt11 alternator woes

Posted: Tue Jul 30, 2019 5:40 am
by Dneprswede
Hi fellas. I got my alternator back together with new carbon brushes today. Everything mounted up and a healthy battery. I still don't have any charge going to my battery and the charge light is on permanently when I turn on the key.

What else can be measured on the alternator? Diode pack?

Alternator has +12v on terminal marked + and whenever I turn the key on it get the same voltage on w terminal. No change in voltage when I rev the engine higher. This would indicate something bad with the alternator itself right?

Re: Dnepr mt11 alternator woes

Posted: Tue Jul 30, 2019 5:57 am
by Claus
Did you measure the rotor´s slide rings with 10 Ohm and the stator 0.4 to 1 ohm? (check for alternator failure)

Did you excite the field directly from Battery plus like I wrote before? (check for regulator failure)

if both are o.k it might be the rectifier. But with one dead diode the alternator should at least charge 1/2 of capacity (should go over 12,8 V with lights off and 2500 rpm and drop to battery level when lights on)

I have experienced that the exciting line inside the wiring loom is often defective on 650 Ural and MT11 models. You might bypass this line anyway.

Re: Dnepr mt11 alternator woes

Posted: Tue Jul 30, 2019 7:18 am
by Dneprswede
Hi Claus. No, I unfortunately did not do those tests. I shall have to remove the alternator again.

I have solid 12v power on the exciter circuit. My wiring loom is new and checks out ok.

Thx. I'll get back asap.

Re: Dnepr mt11 alternator woes

Posted: Wed Jul 31, 2019 6:18 am
by Dneprswede
Claus wrote:
Mon Jul 15, 2019 2:22 pm


If you want to check the alternator rotor: it should have 10 Ohm resistance between the two copper sliding rings (carbon brush holder taken out ) and no continuity to ground.

I get no reading at all when measuring between the two slip rings. No continuity to ground.

The three phases of the stator should have all the same resistance below 1 Ohm to each other and no continuity to ground.

I get 1.1 ohm on all three phases. No continuity to ground.



The rectifier has three plus and three minus diodes and no pre-exciting diodes. You can check the diodes with a continuity tester for failure.

How do I conduct this test?

Most of the times, the rotor is shot or the regulator is defective.
Also tried with another instrument, not the same brand. Gives 0 ohm between the phases. All other equal.

Re: Dnepr mt11 alternator woes

Posted: Thu Aug 01, 2019 3:46 am
by Claus
Dneprswede wrote:
Wed Jul 31, 2019 6:18 am
Claus wrote:
Mon Jul 15, 2019 2:22 pm


If you want to check the alternator rotor: it should have 10 Ohm resistance between the two copper sliding rings (carbon brush holder taken out ) and no continuity to ground.

I get no reading at all when measuring between the two slip rings. No continuity to ground.

So your rotor has gone south and that´s your problem.

The three phases of the stator should have all the same resistance below 1 Ohm to each other and no continuity to ground.

I get 1.1 ohm on all three phases. No continuity to ground.

That sounds like o.k. As long as all three readings are the same and around 1 Ohm.If you substract the inner resistance of your Ohm meter you´ll be spot on.



The rectifier has three plus and three minus diodes and no pre-exciting diodes. You can check the diodes with a continuity tester for failure.

How do I conduct this test?

Most of the times, the rotor is shot or the regulator is defective.
Also tried with another instrument, not the same brand. Gives 0 ohm between the phases. All other equal.
The rectifier has 3 plus diodes and 3 minus diodes, all pressed into the housing. The diode´s body is one side of the diode, the connector is the other side. Put one probe of ohm meter to the housing and the other to the connector. Measure. Then change the probes from plus to minus and measure again. A defective diode would have two directions continuity or two directions infinite resistance. A good diode has one direction continuity and one direction infinite resistance (cause that´s it´s job). If all three diodes on one rack have the same character, I would say they´re o.k.

As almost always your rotor is shot. The coil is wound too lose and is not covered by resin, so it often dies from engine vibration.
Sometimes there is one coil end broken off it´s soldering to the slide ring. This can be repaired quite easy. But if the insulation laquer has a wear through, it must be wound with new insulated wire by a shop or swapped for a new one if available (where they are off the shelf in Europe since years)

Re: Dnepr mt11 alternator woes

Posted: Thu Aug 01, 2019 4:06 am
by Dneprswede
Thx Claus. I will do some tests on the diodes before ordering a new rotor, to make sure I don't need to order a new rectifier unit as well.

Ural-zentrale has a new rotor in stock for 55 euro. I might try one and hope it holds better quality than my stock one. I don't really want to rewire the bike again just yet, but that might be the clever thing to do in the future.

Re: Dnepr mt11 alternator woes

Posted: Thu Aug 01, 2019 4:39 am
by Claus
Dneprswede wrote:
Thu Aug 01, 2019 4:06 am
Ural-zentrale has a new rotor in stock for 55 euro. I might try one and hope it holds better quality than my stock one.
China clone. Might do it for a while. You might want to order new rotor bearings for it as well.

During the first 12 or 15 years I was very satisfied with my 150W alternator until I killed it by running it with a defective battery. In fact, since that point I had to repair/swap the alternator in very short periods although i could source the best parts out of the large stock of ural-hamburg.de (the owner is one of my best friends).
In the end I swapped to a denso alternator and had no issues since many years now. (including trips like Hamburg/Germany- Vienna- Budapest-Ushgorod/Ukraine- Lviv and back, 3500 mls)
In my opinion one should only operate a 150W Alternator if the bike should stay as original as possible. The time for good quality Russian parts for 650 Ural and Dnepr models is over.
https://www.ural-hamburg.de/Dnepr-Teile ... aram=denso
This is what I have in both my wife´s 750 and my 650 Ural. Pre-used Kawasaki Alternator with custom made adapter for Ural and Dnepr. Two years warranty.
On Dnepr it will fit perfect, for Ural it´s a tad too long and the air filter housing must be modified. It has an internal regulator that doesn´t light the generator lamp.(that has not been an issue anyway)

Re: Dnepr mt11 alternator woes

Posted: Thu Aug 01, 2019 5:16 am
by Dneprswede
The bike will most definitely stay stock or close as for any foreseeable future. No extra lights, heated grips etc. I do however wish to replace broken or bad parts with higher quality replacements.

If I where to buy that alternator you linked, can/should I use my original alternator sprocket? I do not wish to change the entire gear train just yet.

Re: Dnepr mt11 alternator woes

Posted: Thu Aug 01, 2019 5:52 am
by Claus
You will have to use your original sprocket, it works without problems.
Don´t get me wrong: I don´t want to make you a buy new alternator and I don´t get any profit from advertizing parts for ural-hamburg. It´s my personal opinion I made through my own experience.
I love bikes beeing stock after so many years. I hate investing $ 180 every second or third 200 mls trip because cheap fake parts fail.

Re: Dnepr mt11 alternator woes

Posted: Thu Aug 01, 2019 9:48 am
by Dneprswede
Yeah I get what you're saying. No worries! This is a hobby vehicle for me, and even though I like tinkering on it, I'd rather do "fun" stuff than replace the same bad part all over. Example, all wheel bearings and stearing head bearing are SKF. I could replace with russian parts, but would have to change them all in too short time.

I'll check into the what's and how's on changing to a new type of alternator and what changes have to be made to electrical system.

Thanks for your help Claus.

https://www.dropbox.com/s/uwgsk9yqvih5i ... pg?dl=0&m=

Re: Dnepr mt11 alternator woes

Posted: Thu Aug 01, 2019 10:06 am
by propwash
Over the years, I have had similar experience as Claus.
I am lucky to have purchased a "Victor" alternator years ago. It has worked wonderfully.
http://www.russianiron.com/forums/index ... opic=14662

My friend uses the one listed in Claus' link.