This is mostly a documentation post trying to tie together some thoughts.
A few years ago I worked to reverse engineer schematics and operational theory of the Image Engineering DV decoder for video tapes with digital data of laser shows stored on them. These decoders demux 10 DACs worth of data stored on video tape to drive two color laser projectors.
I have a bunch of tapes, and I would like to archive the content before the tapes degrade.
My original research got me to the point where I found the clock and data coming into the portion of the circuit that demuxes it. But I never put a ton of time into getting a microcontroller to decode it since it requires using an interrupt to detect the break in timing to mark frame start — and once I do get the data moved to a computer I need a solid clocked format to store the content and that seemed problematic. (Tying it to a WAV file as sound card captures audio was one thought.)
Then I picked up a ILDA to ADAT converter from DZ/Ed O’Keefe. They’re awesome people from the laser show hobby/industry that make some nice converters. I was originally using modified ADAT to do this operation but wasn’t happy with signal levels, was out to get their ADAT to ILDA box to give me a nice reference to how things should work when I stumbled across the other version. Thinking more about it, and knowing a little bit about the chip in the box I got to thinking…. if I used parallel to serial shift registers in place of the ADCs I could wire the input side to read the data from the DACs in the decoder. The ADAT system (in my case a HD24) would be sampling the data at 48Khz and the DV playback systems runs slower.
Looking into the wavefront ADAT encoder IC, it doesn’t provide all of the clock signals to clock the ADC chips. I found some info on what could be the circuit needed to do the clock dividing:
In this case their clock is 44.1khz and I would rather run 48khz. Also, since I need 10 channels then two chips have to be wordclocked together and hopefully the ADAT is happy.
To keep cabling limited between the old board and any new board I was looking at the schematic I drew out in the past. It’s been 3 years and it took a bit to get back into it. Data bus + chip selects into something that can store state into some sorta shift register that is compatible with the data output of the ADCs that are normally used to feed the Wavefront AL1041AG chip:
A few years ago I picked up a computer w/ a Pangolin QuadMod32 board. This card is an output driver for laser show software from the industry leader, Pangolin. I had a bunch of issues with the card, and managed to work out a deal to buy/swap for a replacement. I own Pangolin’s latest Beyond software which is very powerful and much better so this is strictly a historical endeavor. At SELEM 2016 laser enthusiasts meetup I brought both the luggable Windows 98 machine with LasershowDesigner and an Amiga 500 running the original LSD1000 software. When tearing down I noticed that touching the ribbon cable going to the QM32 board the image was jumping all around. It was obvious that the ribbon cable has issues. On the last digikey order I threw on a DB25 IDC male and female connector, and finally got around to building a replacement cable.
It will get tested next time I break out the laser projector and will report how well it worked. Note, the QM32 is before the ILDA spec so previously I built a converter that takes the QM32 output and converts it to ILDA.
Hopefully one day I will find a QuadMod16 card, which is designed to go in the Commodore Amiga 2000.
First off, I had a problem in my converter that is a DB-25 to DB-25 that converts the older QM32 output to the ILDA standard. I had the red – signal tied to shutter, which was where most of my issues with output were coming from. After fixing this, my new cable worked 100%.
Also, I now have a QuadMod16 card as well. Will be making a cable for that to go from the card to ILDA.
So the prior Commodore 64 audio issue had seemed to be resolved, but when I went to test it with an actual demo it didn’t seem to work. Frustrated I figured I should look into the 3rd C64 that was given to me by Matt C and Mike W. It came from the surplus of Grande Junction in VaBeach, but had markings on it like it had come from CHKD Thrift in it’s past.
Originally there was no life on powerup, but then that changed. It was spotty and upon poking around the glass fuse holder was to blame. Reflowed solder on it and it will still problematic, cleaned the fuse and holder and it was still spotty, bent holder to get tighter grip on fuse and that cured it.
Next sympton was pink screen, orange screen, but not working. Searching online I found a bunch of pointers to things I had already tried (voltage checks.) Finally pointers said it might be the PLA chip, so I desoldered the one out of the donor board (#2) that supplied the SID chip for #1, and placed it in the socket of #3. Came to life, and there was sound from the demo loaded from the SD2IEC.
The metal shielding in #3 was way rusted, and bottom plastic heavily stained. So I combined some parts from #2, and wirewheel cleaned the top shield (which acts as heatsink for ICs.) I sprayed it with yellow rustoleum paint and it looks like a sad Tonka truck but it will perform it’s function and hopefully not rust more.
So check mark on a C64 finally. Claude and Tom are printing me a case for the SD2IEC — whoot! Now to find more d64 images.
Technobeam Case – ReFoam
A number of years ago I picked up 4 High-End System Technobeams from Hard Rock Cafe in Atlanta. They needed a little work, so I fixed them up. I am a fan of High End Systems products, and had owned some Intellabeams prior.
A few years went on and my Technobeams started going to a few events. They would usually get tossed in a large truck unprotected, and given their shape are vulnerable to the plastic heads getting damaged. I didn’t want that to happen so I kept an eye on craigslist. Finally some cases (and fixtures) popped up in nearby Delaware, and I picked them up. The 4 technobeams had a proper home. The case configuration is sort of annoying, as the yoke has to be moved in a position fairly different from the way I normally hang them to store them. But to have a case that allows it to sit elsewhere would take a lot more room, so it is what it is.
But the foam. It was this melty sticky nasty probably open-cell smelly stuff. Mildewish, tacky and gross. It had to go.
Over the weekend I finally got a chance (and some help from Supersoaker and Christian and others) and replaced the foam with fresher closed-cell foam. It’s stiffer, a bit of a tight fit but hopefully the smell will be gone forever. This material was recycled from other flight cases, and we used a Harbor Freight hot knife to cut it. I see it as practice for when it’s time to make custom foam to hold all the flat panel TVs for MAGFest.