[Barfly]

@Sjalabais I want to thank and congratulate you on a well written and comprehensive guide. Informative and lucid it shows what can be done with a little determination. Well done.
Cheers Tony.

 

[Barfly]

@Sjalabais
Do you have the circuit reference of the capacitor that failed? I presume it was an electrolytic capacitor. They are usually the weak link. There is even a forum called badcaps.
Tony. ex TV engineer.

 

[Barfly]

I used to buy a bunch of faulty ECU's on fleabay and refurbish them. Mostly all that was wrong were the connection tags had a "dry" joint. The garages used to rip off their customers with a new one depending on the car make model it could have been a bill of anything North of £800 for a spot of solder and two minutes work.
Tony

 

[Barfly]

The new one:
View attachment 146149
View attachment 146150

OK that is a standard mains filtering cap. Normally used in the first stages of a Power Supply--which is exactly where it is in this unit. They do give trouble, but is not that common, they and the coil in the picture are in the first line of defence of the psu when the mains is applied to smooth the starting inrush.

The usual suspects are the electrolytics that dry out over time, they are much further up the chain normally on the output side of the inverter circuits to smooth the outputs. What happens is as the caps dry out, the output rail becomes more "choppy" and the waveform gets very ragged. This affects the units the power supply is feeding and they shut down/fail to operate with a dodgy power supply.

Tony.

 

[Barfly]

When you put it like that, is there any way to prevent this kind of damage? Why is it so erratic, happening seemingly independent of mileage or charging patterns?

Not really, the mains filter caps do not regularly fail, whereas electrolytics do on a regular basis. The problem is usually the hot environment in which they are working. The electrolyte solution (in this case a paste) just dries out over time. Basically electrolytic capacitors are twin sheets of metallic foil separated by the electrolyte paste and rolled into a cylindrical shape with electrodes connected to each metal sheet that are then soldered into the circuit.
Until a new differently constituted electrolytic capacitor with new materials can be invented/developed we are stuck with this issue.
Cheers Tony.

 

[Barfly]

Thank you for taking your time to explain this. I am baffled to understand that cars get wrecked over a dried out paste. No clear boundaries between planned obsolescence and technological boundaries here, but it's about pennies worth of material, indeed.

I really do not think it is actually "planned" obsolescence! There is no planning involved. When these things are first mooted, such as the onboard charger, the prime objectives for the Nissan design team I am sure were:

1. Cost constraints
2. Ensure the unit is not subject to undue RF interference.
3. Water ingress.
4. Japanese outside sourcing of completed pcb's which from what I can gather is a complicated labyrinth of tiny subcontractors given the input and the output specs. which are required by Nissan. They then design and produce the circuits at as small a cost as Nissan (or other Japanese car makers) can get away with, and even Nissan never get the circuit diagrams and are not interested in what is in the module.
5. Nissan will then design a casing and where it fits in the car.

That leads me to realize there is no big conspiracy on the car makers behalf, it is just the way things are done in Japan.
I always think incompetence, indolence and inertia trumps conspiracy every time. That's not to say that I think car makers are squeaky clean....you only have to look at the cost of spare parts.

I once owned a Toyota Tarago in Australia. The toggle switch for the electric roof went faulty, I enquired the price of a replacement from Toyota - a cool A$ 80.00 I went to my local electronics parts store and bought exactly the same switch identical part numbers stamped on it for A$ 0.45c.

The problem is poor regulation of the spare parts after-sales market, not just in the UK but world-wide. Even the heavily over-regulated EU does badly here, probably because of the vested interests of BMW, Mercedes and the Audi-VW VAG groups. Can you imaging the intense lobbying in the halls of power were such legislation be mooted?

So to sum up; the difficulties of repairing these modules are primarily because of the way the Japanese motor industry subcontracting system works and therefore the complete lack of schematic diagrams of the internals available to anyone other than the original Japanese designers/circuit builders (who may be in some dingy back-street in the middle of Tokyo-who knows). There are two ways of tackling this; reverse engineering, a very difficult and time-consuming enterprise for even a specialised electronics engineer (let alone a hack such as I), or design and build your own unit - not as daft as it sounds, with so many new enthusiasts in the Rasberry PI field a renewed interest is taking place in all things electronic for the talented layman.

Sorry for the extended missive, I just wanted to try and explain why things are not as straightforward as at first glance.

Cheers Tony.

 

[Barfly]

To add to this-I just had a thought-there is a massive gaping hole in the marketplace for a group of talented electronics people to design and build some of these modular components.
The input and output specifications are there in the open, if a replacement onboard charger from Nissan for instance is North of £1000, then a great opportunity exists for a open-source type group to come up with a design, or even a commercial company.
Just musing aloud.......

 

[Barfly]

I can hear the coolant circulate on my ZE0 when charging, too. We almost exclusively charge at night - not for the temperature, but for lower electricity prices.

It is my understanding that a capacitor does not go out gradually, more with a poof!. That is my experience from several appliances, without much deep knowledge. I hope you find the cause for your issues, @whereswally606!

They can go in all manner of ways. While working on a Barco 3-gun projector system with an intermittent fault in my workshop one day (in 1993), an electrolytic capacitor in the line timebase circuit exploded in my face. Luckily most of it caught me on the right cheek, otherwise I may have lost an eye (or 2). Electrolytics usually just dry out over time as the paste loses moisture. Other capacitors mylar, tantalum and disc ceramics for instance usually fail at the point where the material is internally connected to the terminals.

 

[Barfly]

Unless there's physical movement in the capacitor, allowing for contact/no contact, doesn't that mean they fail abruptly, indeed? I always appreciate your feedback and I'm happy you got away from that exploding one!

The last capacitor I saw fail was on my log splitter. That one certainly let go of life abruptly, smoking a fair bit in the process. Which reminds me; I ought to get a new one before tree felling season arrives.

View attachment 147457

That is a big mother of a cap. 60microfarads at 400v ac is a serious bit of kit. I'll bet a new one will cost you an arm and a leg. A log splitter requires a lot of grunt. If you can't find one, go to your local dump and have a look at old 'fridges microwaves and other electrical scrap stuff for one roundabout the same capacity and voltage. It is simply a starting capacitor, and tolerances are fairly wide. Anywhere from 40-80micrfarads will be suitable, but make sure it's at least 400v ac.
Cheers Tony.

 

[Barfly]

Thanks for your advice! Something like this should do it, at 60µF and 450V?:

https://m.aliexpress.com/item/4000016359658.html

Doesn't look all that expensive. A new log splitter is only about 200$.

That's a bit low, might have trouble starting the motor.... try and aim for at least 50microfarads
this for instance....50uF CBB60 Capacitor, CBB60 Motor Starting Capacitor 450V 50uF Microfarad Capacitor Wire for Starting The Motor, Motor Start Capacitor : Amazon.co.uk: Business, Industry & Science
Opps, when I checked your link I was well zoomed out and didn't see the values, just looked at the piccies! They will be fine, cheaper than Amazon too. Aliexpress usually are, but I find them a bit hit-and-miss and delivery can take ages.

 

[Barfly]

thanks - can you provide a link? appreciated

Here is a link to my manuals:- Tony's Manuals