My "NextGen" generator stopped working when we were on our way to Ireland. Nothing unusual about this - happens all the time! I've gotten quite familiar with my beloved generator!

Unfortunately, this time I couldn't fix it... I looked at wiring, capacitor, sensors... nothing! I determined that there must be something wrong with the alternator itself - windings? This was going to take a while - so we'd wait until we were in one place for a decent period.

When we arrived in our winter berth in the UK, I lifted the generator, separated the alternator and took it to a Park Gate in Carlisle to get the windings done - whatever that means... They took it apart and checked it over and decided the windings were fine!

Perhaps it's the diodes? Unfortunately, the place I took it to were uncomfortable going further - they prefer working on bigger stuff. I think I got lucky - even though they spent time looking into the project, becasue they couldn't fix it, they didn't charge me...

I managed to find someone who used to work on this brand of alternator - a Markon BL105 - and he agreed the Diodes were a possibility and guess what - he can supply them - I just need to ID which ones mine has... So I send a photo and he's not seen anything like it! The theory we have is that probably my unit was built in Mexico - after the Markon factory closed in the UK, they moved it to Mexico - it's since closed altogether. While in Mexico, we think they may have done a fairly typical 'cost out' program on the Alternator and come up with cheaper diodes...

My next problem is that my soldering skills are non existent - and since Park Gate felt uncomfortable about it... Fortunately, I have found someone (Chris Dobson) right here in Whitehaven that's willing to 'give it a go' - what do I have to lose?

So now the burning question is will a standard UK diode arrangement fit in my unit and will it work? Will Chris be able to come up with the soldering capability...

Stay tuned for the next installment!



Anybody else had problems with diodes in large alternators??

Bill Balme

Hi Bill, Blown diodes are usually easy to test and diagnose. Start with the easy tests and go from there. I assume if you are looking at windings and diodes that the diesel aspects of the genset are working ok: eg it starts and runs. Dick

Hi Dick,

It's not the testing of the diodes that's tricky in my mind - that's sort of OK - but they have to be separated from the rotor in order to do that test - requiring some pretty high level soldering - which I don't have in my toolkit!

Yes, the diesel is running fine...

Bill Balme

Hi Bill,
Understood and agreed. I was not clear that I did not intend you to necessarily do it. It sounded like the unit was out and accessible and would be able to get to a shop that could execute the work. Back end issues, for me, are harder to diagnose than diesel issues. Are the NextGen people being helpful at coming up with an elimination tree for trouble-shooting?
My best, Dick

Any ideas??

The alternator from my generator will not develop power...

It's at a re-winding company that have tested the coils - all fine. We replaced the diode/varistor assembly (for a second time), they assembled it, flashed the capacitor and ran in a jig at 3000rpm, no power generated.

The windings are good, the diodes are good, the capacitor is good... what can be wrong?
edited by bbalme on 12/5/2018

Bill Balme

Hi Bill, Well, if it were me, I would track the wiring inch by inch and ensure that all the fuses and circuit breakers were as they should be and that there is no fuse / cb existing that you were unaware of. Last tracking of a genset that had all elements checked and working found just such a problem. I am sure this will not help, but every once in a while, the TV is truly just not plugged in. Dick

No Dick... the alternator is AT the rewinding company. They have it on a jig and are running it there. No output despite verifying coil health, diode and capacitor health... I can't think of anything it can be...

Bill Balme

Wow, Understood. That is weird. Dick

Hi Bill,
More time now.
I would stop thinking yourself about what it could be; we are not the experts. And start hammering those who should know: Next Gen, alternator company etc. With Next Gen, I would make clear that you will be writing about this and that you want to portray them in the best light: so please help. If necessary, offer to pay for the consult (they should not accept, but it lets them know how serious this is to you). Push hard to talk to the president or very senior people.
I would also consider finding an expert to look over your shoulder (verbally) at what has been done, the results, the history etc. You will likely have to pay him, but that is OK: that’s his/her job. I have done this a few times with someone I have an ongoing relationship with with good success.
I would consider doing this with Rod at https://marinehowto.com/contact-2/. I think he is superb in all he does, but I am not sure his expertise is in this area. If not, I would ask him to suggest someone.
Good luck, Dick

Sadly the alternator for my generator has been determined dead! The project now drifts even further as I have to fit a new alternator of a different make to the engine. It's the make that NextGen settled on when Markon stopped production, so I'll have some assistance from them - but now I'm into fitting new mounting brackets, new engine mounts, new pulleys and belts... I've located a UK distributor for the Italian alternator, so I can save some shipping there - but the rest of the kit comes from the US - it's fortuitous that I'm headed back to the US for Christmas and hopefully all the ancillary stuff will fit in my suitcase! The project continues...

Bill Balme