Help Identifying a component

[arklin]

Hi guys,
I'm trying to identify a component which I am convinced is part of an instrument of some sort.
It has:
-A 24 volt power source
-Screw holes in the board
-A DIN-5 or MIDI jack
-36 port screw terminals

It is the only remaining component of a gizmo we have which uses MIDI files to turn stuff on and off. It was tinkered together by someone who is no longer with us. He took the trouble to scratch the name off, which was my first clue he was presenting someone else's gizmo as his own (Rrrr). Anyhow the thing has passed to me and I'm working on getting it re-animated.

The connections and general layout of it suggest it is a MIDI-in or MIDI interface for a keyboard. I have also been thinking it could be part of a system like 'Disklavier' or 'Pianomation', or part of something like a Melodica or small MIDI Controller.

If anyone can point me in the right direction, or ESPECIALLY identify it spot-on, that would be VERY helpful (you would be, like, a GOD!) .

Thanks in advance (I hope, I hope)
ark

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Board2.jpg
Description:	Board is about 2 inches by 8.5 Chips are: Microelectronics PIC16c54a-04/p EPROM ST Electronics M74hc259 ST Electronics ULN2803a QT Optoelectronics 6n137
Filesize:	1.09 MB
Viewed:	305 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

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[Uncle Krunkus]

It has a PIC down the left end. That and the 4way dil switch (channel selection) means I would say it is a midi board. The set of screw terminals would tend to point to an after-market midi control board for an older synth which didn't have midi. Or something similar.
That's my guess.

[arklin]

It does seem set up to pass the signal out. So the DIP switches are for custom configuring the thing to different components you think?

I was in contact with a professor from Cal Tech that suggested I go to one of the online discussion groups for PIC16 chips. It is a Microelectronics EPROM. I originally thought the board was made by them. The part of the logo you can read on the board says 'Electronics'. I have started to chart the components, so that if I can not find the maker I may be able to build one. I would -rather- just get another though.

I found a photo somewhere of an OLD synth, that had bell-wire instead of ribbon cable in it. I can't recall where it was now. I've been trying to find an address for the author of 'Vintage Synthesizers' but haven't had any luck. I thought he might have some ideas.

I have actually almost gotten the thing working. I just realized if it has any kind of electrical issues it is not replaceable unless I can find who made the part.

[blue hell]

The DIP switches probably are for setting the MIDI channel. The chip is a MicroChip PIC something ... you will not be able to recreate the device without having access to the program that has to go into that MicroChip thingie ... are you sure it's broken or is it more a question of "not sure how it works" ?

[arklin]

I'm mainly trying to find out who made it IN CASE it breaks. I just had a chat with my boss and he said yes, good, keep looking. Also if I knew who made it I could dig up manuals and find out more about how it functions.

If it fails, and push comes to shove I can probably adapt one of the player-piano devices to the task.

At the moment it works, except one 'channel' on it was burned out. I transferred the wire to another contact. It is quietly humming away turning a bank of lights on and off. It was the missing channel that made me think 'what if I lose this thing altogether?' so I have been searching around trying to find the maker.

I also just realized that the thing is configured with the MIDI jack on one end rather than the middle, which suggests the device is itself a long rectangle. Not much, but it is a clue. Many of the keyboards I have found info on have the MIDI jacks in the back, and side by side.

In addition, I found out some instruments allow you to 'split' the keyboard, which would effectively reduce a very large instrument to the size this one is. This component has the word PCB002 still visible on it, implying there are several of them.

Are there other types of instrument that can hook to a midi controller?
Are there ANY keyboards with the MIDI jack on the end?

Thanks

[blue hell]

Ok, I thought it might be for lighting ... it all makes sense ... it's not a musical thing and has never been part of a musical thing either, it's specifically meant to control "things" over MIDI. Many such devices exist, and it's not uncommon I think to use MIDI to control spots and stuff, so it might even actually be built for that purpose. Or it could be a general purpose thing.

Are you in control over the software that remotely controls this device? If so there could be many alternatives for this particular device. And if not, I think your problem might be bigger than you thought it was

The 002 thing probably is the version number of the PCB.

I did a google for MIDI lighting, but there is a broad range of devices around, not sure what you would really need. Is it just on/off control, or can it dim.

Could you post a better picture, the IC types might give a clue as well, or it might not, you never know

[arklin]

I updated the photo to a larger one, and here's this close up.

I'll 'fess-up and say the thing is not being used to work lights. That was my way of figuring out how it worked. It was installed and configured to run a robotic dinosaur. It's 24v is compatible with the 24v input on the solenoids actuating the motion.

Right now I am using freeware (digital studio) MIDI app to run it, and once I get the thing re-attached I have a Yamaha MIDI Controller that I will upload the file to.

Yeah if you have any suggestions for replacement I would love them. I have a mountain of files I have run across, and vendors who sell stuff for MIDI Show Control that will undoubtedly have what I need.

Frankly although the fact that this thing was tinkered together out of used parts is annoying, it is still a nice piece of work.

If you happen to know what the little silver oval component is that would help. I think it is a crystal or oscillator, but the marking (m004a9t) does not conform to the standard for such things.

Thanks!

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CloseUp.jpg
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Filesize:	1.73 MB
Viewed:	274 Time(s)
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[blue hell]

Ok, that helps

So you got 32 outputs that are able to switch 500 mA at 50 V with diode protection and MIDI controllable. You do have access to the controlling software, so any board with such specs would do ....

The silvery thing is a crystal, probably some multiple of 1 MHz as that would be suitable to make the MIDI 31.25 k Baud signal.

[arklin]

I just completed a chart of the keys this thing addresses. I am not a musician, and haven't picked up a guitar in over a decade.
It turns out you are dead on Blue , there are 32 keys. The device address keys between C2 and G4. I mapped it so I can use the other unused channels to attach to my Digital Message Repeater via relays.
I'm going to begin searching for devices that have their keys within that range, and see if I get any hits.

ark

[blue hell]

[arklin]

Thanks Blue,
You probably HAVE seen stuff like it. Thats what keeps me searching. I know I'm closing in.

No, it isn't an art project (alas). The dino was made over 20 years ago by Dinamation, a company that is itself extinct. One of their former employees repaired it for us using this device, for which we paid a small fortune (something like $9000 USD). I have no clue if he is still around though, as he was in very bad health. Also we have almost no budget anymore.

I am quite certain some company, however small, manufactured it. If I made something like this myself, I would either put my own name on it, or no name at all. The fact that the name was scratched off tells me a lot by itself.

It took quite some time for me to figure out what it was - that it was a MIDI device, and how it worked. As I said I am not a musician - nor an electrician, and I have had to edu-ma-cate myself from scratch. I took a course in basic electronics something like 28 years ago,,, but I am making progress.

Besides you guys, I've written to a BUNCH of people - a college professor, some MIDI experts, some folks who do keyboard repairs, and also a few people who retrofit pianos with MIDI based player-piano controls.

Among their conclusions were:
- "I am sure this was virtually a prototype or if not, a very very small production run. No commercial production run would use that long 'hard wired' connector strip"
- It could be a Do-It-Yourself (KIT) MIDI interface or trigger
- It is very similar to a MIDI to Casio interface
- "It looks a simple circuit with a PIC to decode Midi note on / off
information , latches and Transistor buffers to drive the solenoids"
- "There is a product in the UK called a Kenton KADI which converts Midi
notes to triggers"
- "The board make up looks to be about 30 years old or so"
- "Classic PICmicro device with EPROM program memory and RAM data memory. Features Microchip RISC instruction set with only 33 instructions to learn"

I have identified the Resistors and Diodes (it was the easy part).
The 2 -really small- components (just above the crystal) I think may be capacitors(??). All I can see on them is the letters "AJC", and on the other side "220" which may mean 220 pf (?!?).
The larger round yellow guys (5 of them - some in between the ULN2803A chips) look like ceramic capacitors, but could also be a varistor (?) they have the number "104" on them with no other markings - which might be 100,000pf (!?!?).
Any Thoughts???

Reminds me I need to look on Wiki for what a "picofarad' is...
I can post the list if you like.
I'm going to write a bunch more emails off this weekend if I can. There are a few discussion boards dealing with Embedded EPROM Kits that look promising.
If I find anything I can post it if you like.

ark

[Danno Gee Ray]

It appears you have identified the capacitors correctly. They are most likely run of the mill ceramic types. These ore normally marked with the first two digits reflecting a value in pico farads followed by a multiplier...104=10 plus 4 zeros or 100,000 pf. the 220 could either be 22pf or 220 pf depending on the manufacturer, I've seen them do that both ways.

[Uncle Krunkus]

[blue hell]

22 pF is correct, it is a typical value for the helper capacitors over a crystal.

The way the board is built looks like the way my company did it about 10 years ago for very small series (like up to 5 or 10), it's consistent with the processor used in the sense that the original version of the processor was around at that time. The one actually used is a more modern version of that oldie, indicating that the thing was built more recently using an older design.

[Danno Gee Ray]

Well Unc. it's not a problem. While I agree with youthat 220pf should read 221, I recently cam across a slew of caps that must have been mismarked, they had the zero for the last digit and read on the capacitance meter as if they were marked with a multiplier of 1.

[Uncle Krunkus]

In that case Danno, I have to bow to your experience and judgement, as there is no way my DMM could tell the difference between a 22pF and a 220pF

[Danno Gee Ray]

All is good. I guess the point I was trying to make (which in retrospect I believe really had no beneficial purpose to the discussion at hand BTW) was that sometimes markings and actual values may not always agree. As some in here say YMMV (Your Mileage Might Vary) in one instance mine did. I think you were correct in making sure the most proper information got out to the requester, and with that understanding and to that end...I bow humbly to the moderator in recognition of His experience. All is well as was intended well, as should be well for all.

[blue hell]

[Danno Gee Ray]

I stand corrected...Collectively, Yours.