Hello and thank you for having me
I have an old Invacare wheelchair we are trying to make usable again for a disabled person with no health insurance in collaboration with a local charity.
The chair was donated and looks to be from 2002, the joystick is DX-REM24SC. Reportedly the (very old) batteries were bad, so I replaced them. It turns on, but only works for a few seconds before the error light starts blinking.
I get the 10 blinks error code (CANH bad) so I hooked the CANH line up to a scope and sure enough, I get some activity on CANH for a second or three (varies), but then it stops and I get a 9.6V slightly noisy voltage (when the blinking starts). AFAIK you should never get upwards of 5 V on the CAN bus.
I do have experience in electronics and it seems like the smaller PCB inside is where the CAN-communication (and the problem) happens. There is no visible damage. The TXD and RXD signals are correct on the micro controller pin, but it gets distorted somewhere on the path to the connector of the small PCB - there are a bunch of small MOSFETS connected, probably driving the lines. I was thinking about severing the PCB traces and splicing in a new CAN transceiver, but want to try a more reversible solution first, if there is one.
Do you have any pointers on how to repair this?
For example, I could use a circuit diagram for the controller in case one is out there.
Do you have maybe a source where I could buy a used replacement remote? I understand that this would require programming it and I can probably get some pro-bono help from a local service there. Also, can you replace the DX-REM24SC with a DX-REM24SD remote?
I would be most grateful for any help and/or info ...
Best regards, Franci from Ljubljana, Slovenia