Yet another Machinedrum repair thread

Elektron Gear Machinedrum
#30

Another not tremendously exciting update: I’m scoping and checking stuff out BUT it’s pretty clear something is dead on the CPU board. I’ll futz with the circuit debugger for the CPU that I ordered, but failing any tremendously revelatory things, I’m gonna start replacing chips.

Gonna take some analysis to decide the order, but I bought spare CPUs, flash ROMs, and DSPs. Thankfully they’re still available, and who said there was a silicon shortage… just gotta be in the market for 10-20 year old stock. I’m hoping to avoid replacing the flash ROM, it’d involve dealing with the fiddliest chip package, but we’ll see.

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#31

I’ve become emotionally invested in this thread. Machinedrums must never die! Live Dammit, Live!

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#32

great to see someone who does not give up that easily :slight_smile: i know you will make it

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#33

Ha, I’m glad ya’ll are rapt with attention. FWIW I’m not losing the thread, just waiting on components to come in. I got replacements for most of the chips on the main PCB, and I’m getting as close to the original stuff as I can. Several of them are likely replaceable by more contemporary chips, but whatever, I’d rather start close to known model numbers. I’ll probably get most of them in the next week, though, full disclosure, my 12th wedding anniversary is next weekend so I’m not really counting on getting to devote much time to it until the last week in July (which falls alongside some big work projects, so who knows, might be slow going for a bit).

The one mildly amusing thing I’ll share is that I’m having to find dealers on ebay and aliexpress who even have these chips, but one of the trickier components to find (the flash that holds the firmware) actually shipped orders of magnitude faster because… I found it from a reseller who sells through… walmart.com. Now I know, Walmart just does a storefront thing where anyone can sell whatever, so it’s not literally them, but still, I got a kick out of doing vintage silicon shopping from a place which… certainly has a strong cultural connotation in my part of the world. And it got to me in, like, 3 days.

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#34

Actually, I forgot, there were a few other uninteresting updates:

  1. The CPU debugger works, but some combination of issues with my windows PC and the age of the software are making it tricky to make it totally useable. So I’m running it through, like, a Windows 7 VM on my mac which is netting some, but not a lot of progress, but truthfully I haven’t had a lot of time to mess with it.
  2. It turns out the UI board firmware on the vanilla mk1 is stored on a PIC that is a massive pain to dump with a pickit (PIC16C chip). But this was only the case on early revisions of the instrument as far as I can tell, it seems like they swapped to a PIC16F down the line, which is way easier to dump without having to desolder anything. I have access to a mk1 UW which I will take a look at soon to see if it uses the newer chip since… I kind of doubt that that firmware changed a whole lot for the MD or MM since every single one I’ve seen has the same class of chip in the same spot (in differing packages in some cases) on the UI board. In the unlikely event that anyone out there is willing to open their machine AND they have a pickit AND they are willing to give it a shot AND they have a revision of the board which has an obvious ICSP header (some of them absolutely do): please consider taking a swing at dumping it since it is otherwise lost to time.
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#35

Still waiting on chips but a couple tiny things happened:

  1. Decided to desolder the ROM to dump it to see if it was messed up or not. Seems alright, probably not worth posting anywhere since there are already dumps of the final MD firmware available.
  2. While I had the Chipquick out I decided to desolder and dump the UI chip firmware (I got a TL866 which can dump the C type PICs easily enough). Still deciding where/how I’m gonna post it, but at least I can archive that little tidbit for the ages.

Next step is probably gonna be replacing the DSPs. The former Elektron tech said that was typically the first thing to burn out, and those will be a positive delight to resolder as compared to the ROM. Fingers crossed! At this point I’m willing to Ship of Theseus the main board just to serve as a record of what can be done with old machines. With any luck, by the end of this there will be a complete collection of the stuff you would need to replace any replaceable component on a vanilla mk1.

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#36

kudos for your tenacity man

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#37

I live! Apologies for the interruption folks, a combination of wrapping up and deploying most of my past year’s work, plus a variety of other random, time-consuming life stuff decimated most of my project time for the last month and a half. Figure with all the X.05 excitement, I might as well get back on the horse.

Updates from right before the great darkness:

  1. I swapped out CPU, DSPs, and flash rom. I’m now getting something on the UI data line but it’s not the correct something. So my initial guess is that I flashed the firmware wrong, so I’ll probably be pulling that chip and attempting to reflash it with a few different strategies (futzing with byteswapping the firmware, installing just the bootloader and seeing if I can get it going from there). I am trying this because:
  2. I dumped the borked firmware that was on there. It decompiles to something reasonably sensible, but I ended up having to byteswap it to get it there, and I’m not absolutely positive if that’s because of quirks in how my rom dumper works, how it was burned in the first place, or what. This is where I extra have no clue what I’m doing, so anyone who does have a clue, please chime in if I’m being dense. Weirdly, the firmware I dumped has no bootloader. Not sure if that’s because of a limitation of my rom dumper, some protection on the flash, or if it was just genuinely missing.
  3. I ripped and dumped the UI PIC. No clue where I’ll post it, but I got it if anyone ever needs it.
  4. I got a couple replacements for other chips (RAM). I’m gonna triple check all my soldering on the other stuff I’ve replaced and do my ROM experiments before I even try swapping them in.

Will update when I have something new to say. Fingers crossed I can get this sorted before my Deckard’s Dream DIY kit comes in lest I disappear again!

Edit:
5. I’ve all but given up on the CPU debugger. Maybe I can get it there but right now finding a version of the software that will work on it, getting it running, and finding my way through the development environment seems like not the best use of my time. Maybe some day I’ll try to find a deal on an OEM debugger that works with contemporary computers but… eh, that’s like $200 for something that may shed zero light.

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#38

i have a machinedrum with the dsp2 error, do you think i should start by replacing the dsp chips?

#39

Sort of a silly question but i must have missed it if it was tried, since it can be installed is it possible to remove the +Drive?

#40

have you tried a factory reset?

#41

i would check for bad solderjoints and oxidation first before swapping out some chips… as mentioned here.

1 Like
#42

Howdy, I’ve got a MD MK1 that boots up fully and reports an OK test (shows as the manual does) but doesn’t output sound - I’ve tried a handful of things and have been inspecting voltages inside, checking to make sure values make sense.

My main question is, how does the UI board communicate with the CPU? there are no data cables between the two. From visual inspection we have a 2-wire 5.5VAC 60Hz power cable to the PSU board, another 2-wire 5VAC 60Hz power cable to the CPU board (why? it would be silly to send data this way, I don’t have a scope so I can’t yet read if there’s pulsed info on a 60Hz carrier.) and then the 6 wire connector on the left to the IO midboard, that is directly wired to the master pot.

Secondary question is, if all the joints look good, components don’t looked fried, and all UI events work as intended, where would be the first place to look?

Lastly, did you (or anyone here) do a similar deep dive and learn anything interesting about how this fits together? Any chip replacements you’d stand by?

I checked things in UI to make sure sound worked. Factory Reset the unit. Resat cables. Checked some joints (master vol pot). Checked mute, routing, phone out, master out, outs A-F, level, gain.