MXR Negative Contact Relay Failure........


Mark911

Well-known member
Location
Corona Ca
These bikes are actually pretty simple in regards to the number and type of electronic components within all our "black boxes". Not that the circuity and logic is simple, quite the contrary, it's very advanced. However, the fact is that advances in microchip technology has lead to huge reductions in component count and ultimately the physical complexity of the boards inside our controller modules. Theoretically, this should make troubleshooting easier as there's simply fewer parts to fail and/or test. Alta was also quite thoughtful in regards to embedding quite a number of test points within their PCB layouts which should also make troubleshooting easier.

Having said that, it still requires a good understanding of the system architecture and operation to develop the proper test procedures and expected values/signals. This must be done without even the most basic schematics so it's an engineering challenge to say the least.

On the flip side, all this component consolidation and micronization has issues as well. Certain discrete components have become so small they're difficult to see (even with magnification) yet alone try to identify and perform some kind of repair to. Many of the midsized electronic components like voltage regulators, relays, CAN transceivers/controllers, etc are industry standard but there are some specialty chips and larger MCU chips that although not particularly expensive have limited commercial demand making them subject to future availability issues. I've already discovered that central MCU within the inverter module is no longer in production. On the other hand, the main MCU within the ACM is alive and well, cost . . about $20 bucks.
 

Oded

Well-known member
Location
Israel
I suppose that BCUs failures (and they do fail from time to time) are usually caused by the same electronic component fail.
If we could find that component, we'll be able to fix most failed BCUs, and not replace them, as spare parts are getting sparse.
 

Mark911

Well-known member
Location
Corona Ca
The Texas Instrument part is TMS570LS10106 ARM Cortex-R4F Flash Microcontroller. It's only being produced to fulfill current contracts and therefore is not available for purchase from Ti (I tried). There are other electronic supply companies that have inventory but for how long and in many cases the minimum buy is 60 pieces or more. This is the microcontroller inside the inverter that performs most of the FOC and SVM motor control calculations. Other modules have different microcontrollers.

Chip.jpg
 

Mark911

Well-known member
Location
Corona Ca
I suppose that BCUs failures (and they do fail from time to time) are usually caused by the same electronic component fail.
If we could find that component, we'll be able to fix most failed BCUs, and not replace them, as spare parts are getting sparse.

Like most electronics that fail the most typical suspects are the parts that work the hardest and are exposed to great internal and external stress (electrically, thermally and mechanically speaking). Fuses, voltage regulators, oscillators and diodes are my go-to-first checks. Depending on the failure they can create collateral damage to other components as well, however.
 

Dirt-E

Active member
Location
King George, VA
What does the "force contactors" button do on the battery screen? I've tried to avoid most options until I'm comfortable with them, but there's no explanation for stuff like this that I could find so far.
 

Mark911

Well-known member
Location
Corona Ca
What does the "force contactors" button do on the battery screen? I've tried to avoid most options until I'm comfortable with them, but there's no explanation for stuff like this that I could find so far.
Never had to use it but I assume it closes the two main contactors.
 

Dirt-E

Active member
Location
King George, VA
I talked to Rashid about it today. He said it's there as an extra option to get the contactors to open/close in case they get stuck because of a micro weld. The other option is to tap it with a rubber hammer. Sounds like my kid of engineering 😆
 

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