The ZX81

Well, the ZX first.   It's a 1980, issue 1 ZX81.  So it's only about a year younger than I am.  I also think it's the first time I've ever seen one of these machines in the flesh and it's ridiculously tiny.  The Membrane keypad is horrible.  And the resemblance to it's younger brother is more than just skin deep.  It's really obvious that this is the machine that Sinclair designed just before the Spectrum.



Anyway, A visit to Maplin and one overpriced PSU purchase later, and... nothing.

Turns out this is was my fault.  For some reason, Sinclair decided to change the PSU polarity between the ZX81 and the Spectrum, but I didn't realise this until later.  The 7805 Voltage Regulator got pretty hot, but fortunately it wasn't on too long and it doesn't seem to have done any long-term damage.  Not that a 7805 is a difficult component to replace.

So, a 9VDC Power supply was all this old soldier needed, and it's ready to roll.

Every Color of the Rainbow, so long as it's Magenta or Cyan

So, I've branched out a little.  A schoolteacher friend of mine found a couple of classic Sinclair computers buried in the cupboards at his school:  A ZX81, and a 48k ZX Spectrum+.  The ZX81 was missing a power supply, and the Spectrum was missing nothing, but the keyboard wasn't working:  A common complaint in old Speccies.

Here's the thing.  I have a not insubstantial collection of old Speccies in various states of "not working", including a Plus and a Sinclair 128, both of which use the same keyboard, so I figured we'd be able to get both going in maybe an hour or so.

No.  Ha.

Thought I'd blown the fuse on the Super Famicom.

So I bought a multimeter, which took me a while to get around to it.

but, now I'm sure I've blown the fuse.  Plan of attack involves replacing the irritatingly awkward to obtain SOC fuse with a glass fuse holder.

A little Super Famicom topless action for you.

Aside from dust, crud and corrosion on the shielding, it doesn't actually seem in half bad condition, really.  It's currently running - quite happily, it seems, off a 9v Jaguar power supply.

Which surprises me, a lot of the reading I'd done suggested that I'd probably find a system suffering the "Black screen of death" problem, with a faulty PPU-1 or PPU-2.  With so many variants of the basic chips across many board variants, a fault to one of these is effectively fatal.

Of course, Super Castlevania is an early title for the system, and off the top of my head there's a lot of points of failure this success doesn't rule out.  But I honestly didn't expect to get a Super Famicom which is running as well as this one.

I'm thinking this project may not require as much work as I initially feared.

Colour me stoked.

Welp, I've got it open, finally.  The top shell was in a hell of a state.  It'll require serious retrobrighting at my earliest possible convenience because it's liable to crumble if anyone so much as sneezes at it.  In the end three of the "legs" holding the system shut are actually broken so it's only held together by the top left and two middle screws.

Internally it's dirty as all hell, but that's not really much of a surprise.  Fortunately the bottom shell seems to be quite robust, it's significantly less yellowed than the top (to a degree that makes me wonder if it's been swapped over at somepoint.

Going to need pliers to remove the broken posts from top shell so I can get the screws out and into the SPC and front panels.

edit: pliers located, the SHVC-Sound removed and most of the shielding unscrewed.  It doesn't look too bad internally aside from a lot of crud to clean out.  haven't removed the heatsink yet, but there's no evidence of cap leakage or anything, which seems promising.  There is kind of a weird orange sheen on the board in a couple of places, but I suspect that it may be old glue because it's near the two bus connectors and the RF unit.

The corrosion on top of the SHVC sound shielding and on the controller port pins seems like they could point to trouble area.

Time permitting, I'll order a PSU and AV cable, and get the parts cleaned up over the next day or so, and hopefully I can get some sort of idea what the fault(s) in the unit might actually be.

Huh. I think I could build an NES-compatible joypad.

More interestingly I think I could adapt it to make it compatible with my arcade stick.  Not directly relevant to the Super Famicom, but it looks like that uses a similar approach to it's joypads.

So I think the practical upshot is that I could wire all the buttons in the stick to, say, a DB15 connector, and then connect that to a different controller board allowing me to use a real arcade stick across different home computer platforms.

Images from the auction.

So, for the princely sum of about 14 pounds from eBay, I bought a Super Famicom.  Broken, no cables or controllers or anything.  I had a lot of reasons for wanting a Super Famicom, among them the idea of refurbishing the shell and using it as a home for a Raspberry Pi SNES emulator, worst case scenario.

Higher up the scale was the thought of poking around inside it and maybe getting it working again, but since I have a PAL Super Nintendo, if the hardware inside was completely shot, it wasn't really a major concern.  At the very least I'd probably be able to salvage the controller ports, the Multi-AV port and the shell and that'd be plenty to be getting on with.

On arrival, the shell wasn't in great condition, but I kinda knew that from the photos.  It was slightly worse than I'd thought, but no fault to the seller, mostly because I hadn't been paying much attention to the auction (more fool me).  The top shell is pretty yellowed, has a number of cracks, there's a not unsizeable hole in the back through which I can see a little corrosion on the metal shielding around the SPC unit, but it hasn't daunted me too much, I always knew this was going to be a fixer-upper.

I suppose I'd better see if I can find the Gamebit screwdrivers I own, or get back onto Ebay to order some new ones. I'm not sure I ever had the larger one. But one interesting piece of news is that it DOES seem to power up, at least, so whatever the fault(s) may be, it's not with the power-in jack or the microfuse.