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CORE module (mostly) stopped working abruptly


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Recently got a bunch of stuff out of storage, including all my progress from a few years ago on a simple MIDIbox SID.  I'd gotten as far as a CORE module and a SID module, successfully powered up and connected, and playing the test tone.

So, I was slowly trying to get back to that state, one little bit at a time.  I got my CORE module connected to MIDI, and powered it up, and MIOS Studio reached out and shook hands and everything was fine, all the way to "Application up and running!"

I put it aside for a few minutes, then when I came back to it, it wasn't shaking hands any more.  When powered up, it spits out a correct-looking:

[64989.590] f0 00 00 7e 40 01 01 f7

But then when MIOS Studio sends the big sysex blast to try to make contact, nothing comes back.  (Device ID is set to 1.)

No response from MIOS8 or MIOS32 core!
Check MIDI IN/OUT connections
and Device ID!
For debugging see also
Help->MIDI Troubleshooting

So, MIDI -was- working in both directions, the handshake was working, and suddenly the module won't answer.  I changed exactly nothing between those two outcomes except, like, moving the module around on my desk.

I feel like it's not -broken- since it fires up and sends its greeting, but I have no idea what might have happened to make it act like this.  I did go through the pertinent steps of the MIDI Interface Troubleshooting page, looping back MIDI, jumpering TX and RX with the PIC out, testing voltages and grounds, and everything acts as expected.


Any thoughts?  Thanks in advance, I'ma keep tinkering with this.

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That behaviour could be explained by PSU being overloaded (i.e. box runs, functions OK, but then stops as PSU can't handle the overload). How are you powering things? Does the regulator get hot (careful when touching, they can get very hot!)? etc

Also, it might be useful to provide info like:

- which bootloader you have on the PIC?

- which operating system are you using on your computer?

- which version of MIOS studio are you running?

and so on.

Good luck!

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just check all contacts. maybe the PIC is not firmly in place, midi port connections may become loose over time. it could also be cold solder joints. take a close look at the hardware.

Edited by Rio
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Edit:  Yeah I was just underpowering it.  Swapped to a burlier wallwart and everything is acting as expected.  Thanks for the "PSU being overloaded" pointer, that totally put me on the right path.


For posterity:

So in the intervening time, it started working again, then stopped again, so yes it's something weird and intermittent.  I did get it as far as getting a test tone out of the SID module, so there's progress, even though still a mystery.

WRT other questions:

-- I'm driving the CORE with a generic 9v/200mA wallwart (is 200mA enough for just the CORE idling on its own? Starting to think not.)

-- Yeah, the CORE's regulator can get pretty hot after a couple minutes.

-- Windows 10 x64, MIOS Studio 2.4.9

-- PIC is from a SmashTV parts order years and years ago where MIOS was preinstalled.  It seems to have bootloader 1.2 and MIOS 1.8.  I see that MIOS has moved along so I may try to bump it to current.

-- The PIC is firmly seated in the socket, but cold solder joints are certainly a possibility.  I'll go over the back of the board and look for that.


Thanks for the feedback -- was sorta hoping there might be "oh yeah that's known problem X, and here's the easy fix" but that might have been a wee bit naively optimistic.

So, thinking my 9v/200mA adapter may be too anemic, going to swap in a 9v/1A one I just found.

Edited by emerson
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