Image Engineering “DV” laser show decoder to ADAT direct digital idea

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:

Pangolin QuadMod32 replacement ribbon cable

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.

 UPDATE 8/01/2017

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.

Commodore 64 repair, machine #2

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.

HES Technobeam case re-foam

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.

AMX Netlinx NI-4100 Bad Serial Cap Replacement

10uF cap replacing SMD

This one is pretty well documented on the internet, at least on other AMX platforms. AMX is my automation platform of choice, because it’s so damn flexible. You can write anything in the Netlinx language for the most part, and it’s easy to talk to external things be it via tcp or RS-232/485/422.

There is an issue with the NI-3000/2000 series where the serial ports can no longer transmit due to a bad cap. In my case my NI-4100 didn’t seem to have working serial ports, so I reverted to using the NXC-COM2 boards that were in the unit that added an addition 8 serial ports on top of the on board 7.

After struggling a lot with strange issues using the NXC-COM2 ports, I said screw it let’s replace this capacitor. I wasn’t enthusiastic to remove the unit from the rack but really the job went very quickly.

The cap is a simple 35v 10uF IIRC, and it’s originally a SMD cap but way easy to replace with a through hole with bent legs. Look at that pic, it looks nice! Especially compared to dealing with Konami XMen PCB where the caps leaked all over the board and ate the traces.

The board inside the unit is probably the same board used in the NI-3000, just with the additional board at the bottom for adding the expansion boards. If anything, I plan to “downgrade” to a NI-3000 as I like the form factor a bit better, but in the meantime the DB-9 serial port is running strong (still had issues with the NXC-COM2 after cap replacement, I think it’s my wiring.)

So this worked well.

On that note, I will post some stuff I hacked together for grabbing weather from wunderground and getting into the AMX system for pushing weather forecast data to the AMX EnvStat communicating color thermostat. Mine jams up a bit, it’s been frustrating since it falls out of hold modes based on the schedule (I said hold damnit!) But got the weather hitting the stat via a Linux host, and able to poll thermostat from IRC (No clouds in this forecast.)

BK Precision 1672 Power Supply – Dead channel repair

BK Precision Power Supply test, after chip replacement

Some friends were crashing at my place after MAGFest for the local Awesome Games Done Quick (AGDQ) event. At the time I had a lamp in one of the spare bedrooms but the 2nd spare bedroom had no light source. There is a switched outlet tied to a light switch, but I couldn’t think of any lamp fixtures sitting around that aren’t coherent light or require a DMX-512 protocol. Womp womp, just remembered one in the garage come to think of it. Any how, as a quick fix to solve the issue what better thing to use for a lamp than a 15′ strip of LEDs and a bench power supply? Both were handy, so I grabbed them and cobbled together a 1 minute solution to solve the temporary problem. All is good, except the strip curled back up on itself and shorted. The power supply, a nice BK Precision 1672 with current limiting went into protect mode, but something strange happened. The channel was killed.

Upon investigation the unit would always be stuck in constant current (CC) mode and there was no output. My first suspect was easy, the TO3 transistor might be shorted. No, not it. There were 4 or 5 fuses on each of the power supply boards inside, all were fine. I shot off an email to their support. They kindly replied fairly quickly saying they couldn’t help – but here is the schematics. How is that for service? So awesome.

Looking at the schematics and halfway guessing, I notice a lot of 741 opamps. They are all socketed, so the first easy thing to try is just replace them all. Cheap component, easy work (sort of.) My co-worker Will was placing a Mouser order and offered to let me jump in on it, so some replacement DIP 741’s were had.

Removing the PCB was actually a pretty huge pain. The way the unit is put together, it’s pretty tough to service (although with the bottom of the PCB exposed, I bet shops highly familiar can make easy work of taking measurements.) After freeing the board which requires moving the front knobs, the pot retaining nuts, 4 screws that hold the board in, the metal bracket above the board, and loosening the front plastic and disconnecting a bunch of cables that have little slack I was able to quickly and easily replace all op-amps.

Upon first test it didn’t seem to work right., the voltage adjustment worked like a champ but the current adjustment didn’t — no output. I wanted to keep the unit all together, and figured I’ll just use the right channel and +5vdc.

Upon putting it all back together, I tested it again and it worked fine. I’m thinking one of the connectors wasn’t seated fully, at least that is what I’m telling myself. So the lovely power supply is back in action 100%, thanks for the schematics BK and thanks Will for the 741’s!

And yea, I got a simple lamp for the room.

C64 Audio Issues

C64 No Audio

Picked up a totally sweet SD2IEC board which allows emulation of the Commodore floppy drive from a SD card. It’s similar to the SIO2SD boards that do a similar function for the Atari family of home computers, except for C64. After getting it hooked up and being fairly impressed with the unit I noticed that my C64 doesn’t have sound. The one thing the machine is known for — it’s missing.

First step was checking power supplies. Oddly I had a 2nd PSU on hand, swapped it in place and no go. The internet said it could be a culprit, this makes sense as the power supply has a DC line which would be used by the logic chips that make up the computer as well as an AC line which is commonly used for opamp ICs and stuff that has a +/- power feed. Anyhow the power supply checked out A-OK which doesn’t solve issue.

Next step was to open the thing up, and hunt. Looking online I found details where the SID chip was and the datasheet. Poking at the chip while a music disk / demo was playing I could see the address and data lines were busy so not decode logic or data bus buffers to the naked eye. The thing is the output side of the chip just sits at a high voltage so it seems toasted. I didn’t check the two external capacitors, maybe later. The thing is the SID chip is the value of the machine and places like eBay are full of fake copies from China that don’t function. So this one goes on the shelf until a parts machine turns up.

UPDATE 5/3/2917

Matt Crainer brought me a donor C64 that had already been robbed of it’s keyboard controller IC. I carefully de-soldered the SID chip. I didn’t have a 28 pin DIP socket on hand, and instead of ordering one I ordered some break-away SIP sockets. The quality of the machine pin holes was not up to that of what I would get from a mainstream commercial mail order house machined DIP sockets, but it was good enough. Soldered two 14 position sip sockets. I cleaned up the SID chip first, trying to remove any excess solder or burs on the pins, didn’t want them to bend on insertion. Threw it in. Powered on the C64. I googled for some hints as to how to get sound without digging out the SD drive emulator and found a post from VCF/MARCH forum I believe on some addresses to poke. Noise was heard! All is good. Buttoned it all up and this project is checked off!!!!

Picture added to slides above of soldered in SIP socket.

LED Video Screen Update, it’s done!

A little bit late on this post, but the screen was 100% before MAGFest 2017. 6 frames each containing qty 9 32 pixel x 16 pixel modules are complete. I want the metal ones like the rental screens, but in the meantime it will suffice! The screen is 3 meters wide by 1 meter high, or can be setup as 6 meters wide by 1/2 high. I have the drivers on hand to split it into 2 or 3 separate units as well.

Power consumption can hit 12 amps. There is 480 amps of 5V power behind the screen. 4 modules have color issues (very red), I have spares but have yet to swap them.

LED Expansion 3

QSC BASiS / QSC Dataport to XLR adapters

MAGFest was approaching and I found a sweet deal on a few QSC BASiS units. For the record, I love QSC hardware. I’ve owned a few Digital Cinema amplifiers for many years, as well as a CX series. My goal back then was to have the THX cinema certified amplifiers for my home theater, and at the time people weren’t so aware of eBay. The amplifiers did suffer an issue or two which I suppose can be the subject of another post. There is a service bulletin.

But back to the BASiS units. I was after some QSC units from their RAVE series that use an older standard called CobraNet. CobraNet does UDP broadcasts of audio packets, raw PCM uncompressed. The RAVE units that do analog tend to catch quite a bit more, but I stumbled onto the BASIS units which are meant to hook straight to the QSC amplifier dataports. The dataports are DB-HD-15 (think VGA) connectors that hook to management processors. Note – Don’t use a common VGA cable, all pins must be wired straight through and many VGA cables share grounds among a number of pins.

Doing some research online I found there is no issue making breakouts that go from DB-HD-15 to XLR or RCA, and QSC even sells a breakout board with screw terminals. Sweet!

The bad news? Didn’t get the network working enough in the MAGFest arcade in 2017 to get it working. Next event, and in the meantime I will use my BASIS boxes with my amps to run audio around the house. Once the network is segmented so that the broadcast traffic from the audio doesn’t cause the WiFi to fall over….

SGI Indigo R4K Failure – Let out the magic smoke! Burning smell

SGI Indigo Failure

So I *finally* managed to find the keyboard cable for my SGI Indigo on my last trip to Norfolk, VA. This completed what I needed: the 13w3 to VGA cable, the special keyboard and mouse, the system and the keyboard interconnect cable. I humped the thing onto my desk after clearing a bit of space, hooked it up to my monitor, then switched my first SGI on. It powered on! But then came this nasty smell. That’s not good! It did show the clock TOD error, no chime sound (just clicks.)

I originally bought the Indigo from Reputable Systems (Greg Douglas) in the 90s. I was working tech support at the time, living with my parents, and it cost a good chunk of cash — especially by todays standards. Originally it was R3K with a lower level graphics subsystem that I believe could do some hardware 3d acceleration but only 256 colors. I’ll admit when I first started messing with it I was a bit disappointed. It was still sort of slow, but had good audio capabilities and worked well as an X-term. It wasn’t long before MP3 was a new thing and the system couldn’t decode a 128kbps MP3 real time though, it took about 6 minutes for a 4 minute song — so I would have to write it out then write it to minidisc. Creative commons licensed music, of course.

Somewhere along the lines in my SGI fandom I think I ended up with a 9u VME frame that had an ELAN graphics boardset on it. I also ended up with a 2nd SGI Indigo from NASA auctions I used to frequent, one with the faster MIPS R4000 series CPU (R4K.) I remember posting that I was giving away a bunch of hardware including parts from the NASA Indigo, and left it and other stuff behind my office in Virginia Beach for someone else to pick up. But a homeless scrapper got to it first, taking everything metal and leaving plastic shards of laser printers and SGI Indigo (and other equipment) behind. Ugh.

But I held onto my Indigo, not having looked at the CPU cards in a long time. The first thing I did was pull out the CPU card and thought, “man this is bulkier than I remember! What a crazy heatsink for this slow R3000 processor.” But it turns out the R3K board isn’t a R3K board, it’s a R4K board. So then I’m thinking, “Okay so I guess I kept the R4K CPU and the lower graphics board.” But no, the graphics boardset looks stout. So I guess I kept both higher end parts and gave away the old R3K / Entry stuff. Or maybe the Entry graphics was in one of the bigger deskside systems on the frame the Elan came on. I can’t remember.

I remember that the Indigo had two power supply options. One for R3K/Elan graphics and one for R4K. I thought you could use a R4K with entry graphics on the weaker power supply as well. This was a huge issue in my mind since I figured my Indigo had the R3K PSU. I pulled the PSU from Indigo (My Indigo was always named Eggbert from a Super Mario Bros 2 character of similar name that was purple, so from here on it’s Eggbert.) So Eggbert’s PSU turns out to be the R4K model! I opened it up, the capacitors look okay but that really doesn’t say much. No burnt smell inside PSU.

So back to sniffing the circuit boards more. I sniffed and sniffed. Two times over I missed the roasted capacitor on the bottom of the CPU card. I was thinking it had come from the graphics boardset, which sits in the case right next to the bottom of the CPU boardset.

The fried capacitor is C531, and this is near the sound section of the CPU board. No telling what it actually goes to but the lack of the chime sound might have something to do with it. Image slideshow above has a picture of the fried capacitor. Audio sections of computers often use the negative voltages for opamps and DACs where the rest of the computer might not use these voltages, so I might have to check to make sure the power supply isn’t doing something bad on the negative voltage outputs (if it has them.)

In the process of diagnosis I have made a list of all similar style capacitors on the board. I don’t know what is wrong with the machine, but if this style/make of capacitor is degrading from age then the solution should be to replace them. They’re SMD, but pretty large SMD so replacement shouldn’t be TOO bad.

So here is a list of the capacitors I have made so far. I’ve only researched 2 of the 4 with regards to what standard the size is. I have what I believe are DigiKey part numbers for the value that fried and the most common other value (prob used for noise filtering on the power rail.)

I measured the size with a caliper and best guessed on what it equates to in industry.


SGI Indigo SMD tantalum caps of the style of the one that burned up:

Top of PCB:
C14, C15, C23, C48 = 47uF,16v
C30 = 33uF, 20v

Bottom of PCB:
C555, C544, C525, C513A, C513B, C578A, C578B, C645A, C645B = 47uF, 16V
C697 = 33uF, 16v
C551 = 33uF, 20V
C507? = 10uF, 10V

C551 is the crispy one

47uF/16v = 7.3mm x 4.42mm : Size 2917 (7343 Metric) / Digikey – 478-1739-1-ND
33uF/20v = 7.44mm x 4.33mm : Size 2917 (7343 Metric) / Digikey – 399-3788-1-ND
10uF/10v = 5.5mm x 3.3mm :
33uF/16v = 7mm x 4.45mm :


I will also have to do a battery holder mod since TOD battery is dead.

More updates once replacement caps come in and I replace them.