Last night I updated my post featuring the external power supply I offer for the Cheetah MS6, after receiving an electric shock off a customer's unit. This morning I thought that I really should do more and so I've decided to launch a separate post about the issue, emphasising the fact that not just unreliable but that the Cheetah MS6 factory power supply is dangerous. There's not a lot to say but hopefully it'll come up in search engines.
So let's consider a few issues of the Cheetah MS6 factory power supply:
- The transformers are famously unreliable.
- Power supply components are packed very tightly together.
- The heatsink is for the regulators is rubbish. On some examples, it just floats on the back of the regulators while on others, it’s mounted via a couple of self-adhesive stand-offs, to the inside of the case.
- The gap between the bottom of the case and solder joints, etc carrying mains voltage, is insufficient.
- The voltage selector switch on the back of the MS6 case, isn’t covered and can easily be knocked from 120V to 240V or vice versa.
- A lot of mains points are exposed inside the case. For some reason, the fuse is covered but what's the point???
- The gap between the memory back-up battery and the mains fuse is very small and can be cause for short circuit.
One issue that's not directly related to safety unless it leaks, is that the memory back-up battery is an old NiCad type of cell. As stated above, it's mounted very close to the internal fuse and other mains carrying points. If and when it leaks, damage to the printed circuit board is one thing but compromising safety, is another.
When I provide my external power supply, I always recommend that customers take me up on my offer to upgrade the battery to a high-capacity, modern lithium battery. The circuit needs to modified slightly, to accommodate the newer chemistry battery but it's well worth it. My modification makes the battery a user-changeable part, with no soldering involved. Nicknamed 'Live Forever', it obviously won't but it will probably outlive your MS6!
There are several design issues with this otherwise great little sound machine but the fact that the Cheetah MS6 factory power supply is dangerous, is the most serious. No one really wants to die while playing a synth module, right?!?!? My external power supply for the Cheetah MS6, resolves many issues and above all, it is safe! 😊 You can read all about it here.
Pictured above, is another MS6 I have in at the moment. I believe that the PCB in this machine is either a prototype or a very early version. It's not as deep as 'regular' PCBs, so much so in fact, that it doesn't sit on the front-most PCB mounts. Instead, the front part of the PCB is secured with self-adhesive PCB stand-offs. You can also see some wires around the place which just aren't there on other MS6s I've seen.