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Michael Kukat
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Keyboard intensive care

I had a different plan for today, but first, i wanted to replace the rubber feet of my Amiga 2000 keyboard because they dissolved already and left a mess here and there. Shouldn't take long.

Replacing the rubber feet in fact didn't take too long, but longer than expected due to the goo not wanting to be removed. During this procedure, the numeric block 0 fell off, and i noticed that the Help key also is stuck somehow. Okay, i need to fix this.

I quickly found out that this was not the first time the 0 fell off, i already fixed this a while ago, and as the rubber spring was also missing already, i stole it from the least used key - Help. So the first try to glue it back together already failed and the second will also not be so much more successful. Wait, i have this old, dirty, ugly A2000 keyboard in the basement, let's see if i can steal the key there.

I quickly found it but then i noticed the C= key in place of the left Amiga key. That's something special. And it feels completely different than the other one, much harder feel, not the dead octopus of the regular Amiga keyboards. Having a closer look revealed it's one of the very early mechanical Amiga keybaords, an NMB Hi-Tek. Not only don't fit those keycaps to the cheaper Mitsumi keyboard, it would also be a shame to not restore this great keyboard. Even better than the Cherry, which has some trouble with some games not using the OS to talk to the keyboard but bringing their own routines for this, violating some timings.

So i took it apart, removed all the keycaps, which was not that easy sometimes, i ripped out the whole key body of two keys, but no damages. While the ultrasonic cleaner had it's portion of work (and this time, it really did it's job right), i cleaned the rest, removing plenty of debris, still leaving some rust behind, but for now, it's okay. I had some more fun putting the metal supports for the larger keys back in place and finally had to unsolder 4 of the keys to avoid damage by forcing those parts back in place.

Anyway - besides some yellowish tint of the enclosure, this keyboard looks and works like new now. Wonderful. I hope the glue of the other keyboard is also okay now. Ah, and it also got new rubber feet, they started to dissolve already. I'm still not sure if the cable is original because not only is the soldered DIN connector a bit strange, in the keyboard itself, the connector also looks a bit suspicious.

Now i can't sell my fully-loaded A2000, because it has such a great keyboard :)
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The Raspberry Pi's grandfather

While scanning through some old floppies and tapes to image them, i found another set of floppies for this nice thing. As i'm pretty sure i never had documentation for this board, it might be as complete as it can get now.

Datakamp EPC II Z80 board, Data Research CP/M 3.0 for it, plus backup disks. I'm sure it was quite expensive back then, 30 years ago. At least more expensive than a Raspberry Pi (or whatever modern ARM-based embedded toy you prefer).

I want to test this thing one day. Too bad there is not much documentation available. As this board even has a video output, it might need a keyboard, which makes things a bit more difficult than just hooking up a serial terminal. But let's see what happens. Okay, might take some more months or years until i find the time for this :)

Oh, wow, just found out that Datakamp still exists:

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SGI Indy first power-up after many years

Okay, i carefully checked the monitor, removed some dust, had a look at the capacitors, everything looks good. Still a good adrenaline kick after powering it up and hearing the typical noises of the degauss coil and the high voltage building up. But - just works.

The hard drive seems to be close to death, it took half a minute to complete the first seek, but it boots. And i think i had my home directories of an NFS server back then, so without network this won't work. I think i should give it a fresh installation and then carefully think if i want to sell it or keep it.

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Too useless to keep, too nice to give away

I bought too many cameras and now something else has to go to make room :)
My SGI Indy was not a candidate and still isn't. I mean, i got rid of all CRTs (except oscilloscopes and, well, cameras :), but this one (and another beige 17" SGI screen) was kept, i even gave away all the 20" SGI CRTs i had (5 of them, IIRC). I didn't turn on this machine since many years, and even if i would, i likely might install a fresh IRIX and put it back to the archive. So there is no logical reason to keep it.
But an Indy with a 24 bit frame buffer, 256MB RAM, original IndyCam, matching CRT, keyboard and mouse, this nice setup just lacks the silent Sony PSU for perfection. I think i even fixed the NVRAM some years ago.

The speakers and additional microphone belong to my Octane, but as this machine is FUBAR, the Indy inherits them.

I'm too cowardly to power it up right now, i need to have a closer look at the innards, especially of the CRT, first. I don't trust anything that uses capacitors. Every piece of electronics gear that wasn't powered up for some years needs a closer inspection before waking it up again. Half of the times i don't respect this, stuff reminds me with a big bang and an ugly smell. And some evil work afterwards to clean a PSU from capacitor guts.

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Let there be knobs&sliders

So i used the long weekend to hack a bridge between this Crumar GDS keyboard console and the DIY hybrid synth prototype. Even if the DIY synth is heavily inspired by the original GDS, it's hard to bring them together in a useful way without having the computer screen in addition, and i didn't want to go that far because at the end, this bridge is just a throwaway module not required for the final user interface.

The GDS keyboard (without the GDS system, which i don't have) is connected to USB and/or MIDI using my DIY interface box. I added a simple way to control the LEDs of this console (program changes, 64 LEDs + 1 on/off bit = 7 bits, so it was the simplest way at the moment) and added another provisoric client to the synth engine control interface. It's not great, but enough for some testing.

You can add/remove any of the 24 sounds to the engine, up to 8 layered sounds are supported. You can tweak the most important parameters of those sounds also, basically what you can do with a DK Synergy minus what's not yet implemented.

In addition, you can edit all 16 oscillators (okay, most sounds only use 3-4 of them), again the most important parameters, especially the filter (which is a kind of 32 band graphic equalizer, controlling the output level of the oscillator based on it's frequency) and the envelopes. I think i should add some special handling to the "frequency factor" knob. Because FM synthesis alone already is a bit challenging, but tweaking FM sounds without having an idea what parameter values you really dial in is, uhm, interesting. But lots of fun :)

Besides this, some code cleanup, "efficiency" leftovers converted to more readable, modern C++ style, because they are no longer necessary now, after lots of other stuff is optimized. So i could reduce the CPU load on the embedded system another little bit, giving back some more headroom for some still missing features and other stuff, that might make it into the final engine.

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Uses for obsolete surveillance cameras

In this case, a Panasonic WV-CP240EX. The sixpack was cheap :) I think those make sense as helpers for soldering, drilling and other work where my old eyes could use a bit of support and the large lense magnifier is not handy enough.

Another plus of those cameras is the light sensitivity. Even with this very bad lighting, the image is really okay.

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I couldn't resist. Small surveillance cameras using Vidicon tubes! I found them on eBay and after seeing i decided that i want them for the collection.

I'm not sure about the age, the serial numbers of 2 start with 77, another one with 83, maybe 1977-1983 isn't that implausible for them. Panasonic WV-71. You might notice that they have just one single BNC connector. And exactly this makes it a little bit difficult to get a video signal from them.

After searching the web for a while, i found a service manual of a WV-BM90 monitor supporting those cameras, so i can look at the interface. No schematics of the cameras around there.

Technically, it's an old of up-the-coax implementation, so this single coax cabel delivers power to the camera, video from the camera back to the monitor and in addition, the monitor delivers vertical sync pulses to the camera. According to the service manual, powering the camera is constant current 220mA (which makes sense, because this way the cable length doesn't matter), you can decouble the rest with an electrolytic capacitor from this. The vertical drive signal are 5V pulses on top of the normal power.

My standard CVBS monitor doesn't really like this way of non-standard signal, so i need to build something to remove the vertical drive pulses from the signal and likely add real vertical sync signals instead. This needs some more experimenting and research. I even don't get any video output on the coax at the moment, but all 3 cameras show a signal after the target preamp, so in general, they work fine, the might just need the right signals to throw out an image. Which is pretty amazing after likely several decades of 24/7 operation.
Okay, one has a leaking capacitor, but this was somewhat expected. Even if it's rare with Panasonic gear, maybe they use Panasonic capacitors, which i also like as replacements for repairs.

Just wanted them for my collection, but when i have some more time, i'll dive deeper into this to make them work :)

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Weekend soldering

Done. The provisoric setup of the DIY hybrid synth works. Soldered the 16 reconstruction filters yesterday and cared about clean power routing today. The output still is just an opamp on the breadboard because there are 16 VCFs and 32 VCAs missing for the full prototype.

Still enough to play with it. The computer just does MIDI routing and oscilloscope view here. Not perfectly noise free, but for a veroboard construction, it's good enough.

2 more days of the long weekend available for software stuff. For today, it's enough. "Wasting" some time out there in the sun.
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Fine. Installed +Ubuntu 18.04 this morning on my Acer Switch Alpha 12 after deciding this machine is very nice for Ubuntu with some weeks of running 17.10.

Hopefully the GPU freezes in KiCAD pcbnew i've seen with 17.10 are gone with the step back to xorg, i'll see the next days.

Installation worked fine, just one issue found: with the default 200% GUI scaling, the installer crashes. Set to 100% before installing and everything works fine. And as usual with this machine, you need to add shimx64 to the trusted EFI binaries after installation, otherwise you can't boot to grub, at least not in a dual-boot setup. I didn't boot Windows as often as this morning during the last 10 years or so :)

Compared to 17.10, the suspend on closing the keyboard cover and especially ware-up on opening it works without any workarounds.

/me approves this as a very nice Linux 2-in-1 device.

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Sony DXC-M3A inside look

And the last arrival for the vintage video camera collection. A Sony DXC-M3A. Just 18€, plus expensive 12€ shipping. Sold for parts only, unknown condition. Without lens and viewfinder, the seller sells those separately for 249 and 59€ buy-now, not an option. I'm sure i'll find a suitable lens some day. And the viewfinder would be only nice for completion, technically, i have hacked a solution already :)

The first 2 or 3 tries, it powered down after some seconds, maybe the capacitors need some wakeup before everything performs great again. But at least i didn't find any leakage and with a provisoric photo lens i could test it. Works great, very sharp picture and with the video output, i also get a color picture (the VF output is monochrome only). It's amazing how good this thing seems to perform for a triple tube camera. They are known to be a bit problematic to get the 3 images of the tubes together correctly, it's completely analog, so no easy to synchronize pixel stream like from a triple CCD camera.

But i wanted at least one triple tube camera in the collection and this one is the last one Sony built, i think. And i wanted a broadcast camera with several boards, a friend who did video products had one open for display in his studio 20 years or so agi and i always liked it. Now i have my own :)
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