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CAN bus not working


Digineural
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I'm putting in a few mods to my MB6582 and getting around to one outstanding issue since I've built it. The CAN bus isn't working so I can't clone the core. So far I've replaced R80 twice and nothing works.

Here are the stats:

1. All 4 cores are stock from Smash - I'm assuming they aren't the problem since they've all been checked and post a "Ready" status

2. Core 1(ID:0) has 2 6581 set to 12v jumper - this pair and core is working great :smile: which is why I've waited so long to try core 2

3. Core 2 (ID:1) has 2 8580 set to 9v jumper - not getting hex via midi jumper change or cloning from core 1

4. Cores 3 (ID:2) and 4 (ID:3) are installed but not populated with SIDs, again cloning doesn't work

Using a continuity check on the pads for R80 the measurement is .781 with the 1k resistor installed and .990 without R80.

Any ideas?

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  • 4 years later...
  • 11 months later...

@TK.

Wow, it's been almost a year since I followed up on this.. 
I still have the problem. All my cores have the latest firmware installed, and have correct device id's and respond when I query them with MIOS.
Just the cloning wont work, and selecting SID 2..4 from the control surface says "CAN DISABLED".

I have almost exactly the same pcb next to it, stuffed with same parts, which does not have the issue. Checked D1_COREx orientation, R80 and such. Removed all cores, checked continuity between D1_COREx's and their respective pin on the CORE
Quite clueless atm. Hints are welcome :)
 

Edited by rvooh
added some more info
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So, you mount the 4 PICs of the non-working board into the other board, and CAN communication is working there? This is an important information!

Concerning continuity checks: remove the PICs while checking it.
Compare with this interconnection diagram: http://www.ucapps.de/midibox_sid/mbsid_v2_communication.pdf
And this schematic: http://www.ucapps.de/mbhp/mbhp_core_v3.pdf

Expectations:

  • pins #36 of the PICs (RB3) are directly connected together.
    They should show continuity to each other.
    No continuity to ground (Vs)
    No continuity to 5V (Vd)
    But should show 1k resistance to Vd
  • pin #35 of the PICs (RB2) should show
    No continuity to ground (Vs)
    No continuity to 5V (Vd)
    continuity to pin #36 only if the negative probe is connected to pin #35, and the positive probe to pin #36 (due to the diode)

Results?

Best Regards, Thorsten.

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@TK. thanks a million.. my issue was a broken trace underneath PIC 1, causing discontinuity between pins #36 (see attachment). It's fixed now.
probably happened cutting the ic-socket, more than 7 years ago.. doh! There wasn't any visual scratch to be seen though...

Enjoy the beer :cheers:

mb6582fix.png

Edited by rvooh
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