On my desk today is a game console from the 90's called Dendy (Де́нди), and as the cyrillic implies, it was aimed for the Russian market. A friend of mine recently got his hands on this console, but since it did not appear to work I was asked to have a look at it.
It's like the design is from a Star Wars movie
Opening the case was no big deal. 6 Phillips screws later the case was open and the main PCB was exposed. I did some work on an original NES a couple of weeks earlier, and was expecting something a bit more... uh, "more" than this.
Take me to your leader
At first I thought this was the interface board, and that a smaller, more populated board wold be underneath. But no, this was it: a single-sided PCB with a penny pinching sprinkle of passives. Worth noting is the center-negative 9V power input, which is regulated down to 5V via the linear 7805.
When I saw the bottom of the board, I had one of those "a-ha" moments that you read about on blogs. So, "a-ha". This is a NOAC (NES On A Chip) clone system. The UM6561F-2 does all the magic involving CPU, GPU, audio and I/O.
What's interesting on the mechanical topic, is the cartridge ejector. Just like the one on the Famicom consoles, except it doesn't work. Here you see the plastic construction consisting of two two wedge shaped ejectors that are supposedly there to eject the cartridge, however this construction is so weak that I hesitated using force on it.
Here's how it works from the cartridge view. If you try this with a cartridge the ejector will
Anyway, back to the repair job. It was in fact dead simple, and only a matter of a dodgy barrel connector. A replacement was donated from a dead Arduino. I applied a generous amount of solder to make sure it stays in place. However, I would consider hacking it to be center-positive, since this is more or less the standard and opens for a wider range of power supplies.
I was tempted to dump the cartridges, and opened one for inspection. Turns out they are budget chip-on-boards and not 27-series EPROMs as I was hoping for. Dumping them is not impossible, but I requires a bit more effort.
One last thing, though, and that's the neat joystick slots on the side of the case. These are nice.
Oh, and animated GIFs instead of Youtube videos - yay or nay?