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Thread: Can: not ready in can Car

  1. #11
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    Here is the board from both sides.



    Julian

  2. #12
    Benevolent Dictator Uwe's Avatar
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    OK, so the MCP2515 in the first pic is the CAN controller. But I doubt that's where the problem is; it only controls the CAN "logic" and is not the transceiver. There should be another, separate transceiver chip, as well as two 60Ω terminating resistors. I don't see those in the pic, so I suspect they are hiding under that big TO220 package 5V regulator. Bend that up and out of the way and show us what's under it.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

  3. #13
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    The MCP2551 was indeed hiding under the voltage regulator, but no sight of any resistors in the 60Ohm range.


  4. #14
    Benevolent Dictator Uwe's Avatar
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    Yep, that's it. MCP2551. I couln't remember the part number. I'm sure you can find a datasheet for it...

    Looking at your picture in full-size, I'm wondering whether this bit of solder should be there:



    That's the CAN-L pin. You might take a dental pick or, if needed a fine-tipped soldering iron to that and see what happens.

    -Uwe-
    The engineering problems are likely insurmountable. It would be like proposing to land a rocket booster section on a barge floating in the middle of the ocean.

  5. #15
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    Judging from the copper color that appears after scratching, I would say this is a valid path. I need to get myself a magnification glass, as I don't have one here. I've ordered the MCP2551 but it will take 2 weeks to arrive.

  6. #16
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    I've desoldered the MCP2551 and a 120Ohm resistor between CANH and CANL on the right side. I still have a short to ground for CANL. I'll resolder the chip but I don't know where this short is coming from...

  7. #17
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    Hi Uwe,

    I have resoldered the chip and desoldered the plug board. I still have that contact from CAN-Low to vehicle ground. I don't know what to think of this. I cant spot any components on that board.


    I've also tried to desolder the plug, but Ive failed so far as i dont get the rest of solder out of the mounting holes.

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