I know there are already existing posts about this problem, e.g. here and here, but I think my recent finding warrants a post of its own.
I have a Machinedrum MK2 that started having problems booting years ago. On power-on, the display would glitch out showing weird characters, or not show anything at all, even though the display was powered. I could always boot into the early start-up menu okay, but not into the normal menu.
I tried cleaning and reflowing the inter-board connections. I even replaced the UI board and PSU board. These attempts only temporarily fixed the issue at best because the problem would always re-occur hours, days, or weeks later.
I suspected the problem was due to the power-integrity of the Coldfire MCU on the CPU board, and Chat GPT supported that hunch. Following Chat GPT’s recommendations, I replaced the tantalum capacitor between the MCU’s VDD pins and ground with a 22 µF 25V electrolytic cap.*
*Chat GPT recommended replacing it with a 22–47 µF ≥10V ceramic cap, but the nearest to those specs I had at hand was the electrolytic. I’ll swap that out with a more suitable ceramic cap when I get a chance.
Lo and behold. After changing the capacitor, the Machinedrum booted normally on the first try. I’ve yet to see if it’s a permanent fix, but the results support my suspicion about power-integrity being the problem. Hopefully this can be of help to anyone else experiencing the same issue.
Location of the tantalum cap (note this is not my board pictured below. On my board, the part number is J106L. It’s likely a different part on different models/board revisions):
The capacitor probably has the same numeric code on other machines, or very similar. I think J indicates a 5% tolerance and 106 is the code for 10 microfarads. I don’t know what the L stands for but this should be an indication of the part value rather than an elektron part number.
Definitely good to observe the number itself but unless they changed this part out for a different value at some point, it should probably be the same or similar.
Yes – on my particular board revision, it’s a 10 uf tantalum cap. On other revisions, it’ll probably be the same value, even if a different brand/part number was used. It’s unclear whether the voltage rating for the part on my board was 6.3 or 10V, but it’d be safest to replace with a another cap rated for 10V or higher.
Awesome outcome. Another MD saved. Thank you for sharing the knowledge and adding your findings to the MD repair knowledge base. Also great/positive that Chat gpt was able to assist with your hypoth.
mine just started doing the same thing!
i dont know anything about engineering./electronics… i ordered a new power supply because last time it was having these kinds of boot issues it was definitely the power supply, the one i have currently is a cheapy $12 one from amazon, ordered a larger one (that looks like the original) from ebay. I hope this solves the issue, but now i dont know after seeing this.
If the power supply doesn’t help you’ll likely need to unscrew the lid and you can start by gently unplugging the ribbon cables and cleaning the copper contact points with isopropyl alcohol. It should dry pretty quickly and then you can reseat the cables into the receivers on the board and check for improvement. If it’s not helping you may likely need to get a tech involved and show them some reference info from here.
If it’s a MKII device, you can still schedule a service appointment with elektron but if it’s MKI you’re on your own so it would be a good idea to check with music stores or electronics repair in your area to find out who will work with you on a machinedrum.
In most of these cases, it’s a connection to the UI board that’s the problem. Clean and, if possible, re-flow the solder on all connection points. Areas to focus on are the 2-wire cable and connectors between the CPU board and the UI board. I’m pretty certain that’s where communication between the CPU and the display happens. If something’s not right there, it can make the display appeared garbled without crashing the firmware.
