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Hi everybody, I was fed up to boot the computer each time I wanted to try a new SYSEX...so I designed a ROM card for the DX7 built around a 27C801 EPROM ( 1MB ) and ended up with a perfectly working device able to store 256 x 32 = 4096 patches...whereof to stay awake late in the night before needing to erase and burn the EPROM again.... There's no mystery in my design, based upon the original ROM card circuitry supplied by Yamaha, which I extended the adressing bus with 8 additional lines controlled by DIP switches for highest adress bits, allowing selection of one of the 256 banks. I had to write a ( rough for now ) Python script to extract datas from SYSEXes ( basically to remove the MIDI-dedicated bytes ) and to build the .bin file to be sent to the EPROM programmer. For now, I filled the ROM to the brim with 256 SYSEXes picked up at random ;-) As said, the prototype seems to work very well ( though I didn't test every single patch....) If someone is interested in such a device, I can launch a batch at OSH Park for PCBs and send them once I've received them. I can also supply rightly programmed 27C801 EPROM, or even a complete kit with all the components ( a few indeed ). Let me know ! I attach to this message pictures of the card and the script I used ( in French, sorry....).
Chris.
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Thank you for posting this. As Daniel has mentioned there is perhaps a large amount of pent up demand for something like this. Is there no issue with using the PCB traces as contacts? I know this has been done in the 80's and 90's but it seems all the recent attempts (even here on this group) have failed to achieve popular success because of board thickness or some other issue making them unreliable. I hope yours does work.?
Also, OSH Park allows customers to buy boards on demand so it's possible for you to make it available that way and people buy direct from OSH Park and you receive some compensation. I'm not exactly sure how all that works though.
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Hi Daniel & grant, thank you for your answer !
I suspected someone did it before, but didn't look further...Actually, I have a bunch of 27C801 in the bottom of a drawer and wondered what to do with them ;-)...
@Daniel
For now, I only ordered the regular 3 pieces batch from OSH; there's one unpopulated card left, the two others acted as prototypes...The total amount for that batch was 45�, so a card price is 15�. Including EPROM, all the components and shipping costs, I guess a total amount of ~30�...
There's no problem for me to burn your own SYSEX : you've just to send me the list of the patches you want to be included in the EPROM ;-)...
I don't plan to design cards for other machines, as long as I don't own them ;-)...Maybe later, I'll cogit about an Arduino/SD Card interface for my DX7...
@grant
Yes, I noticed the existence of cards using PCB traces for contact...the thickness of the PCB sold by OSH seem to be satisfactory, I didn't encounter problems of bad contact...Of course, it's necessary to see in duration after many insertions/extractions...I can't tell, it works perfectly for now !
Of course I would be glad to make the board available on OSH; I'll see how it works.
Chris.
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Hi Christophe - that's great news! Maybe you want to post your outcome here:
http://www.yamahamusicians.com/forum/
There's lot of activity reg. Yamaha synths...
Regards, Miks
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I'm interested? Let me know about total price ?to USA
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On Sep 16, 2017, at 12:34 PM, christophe.perrod@... [YamahaDX] < YamahaDX@...> wrote:
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Hi Daniel & grant, thank you for your answer !
I suspected someone did it before, but didn't look further...Actually, I have a bunch of 27C801 in the bottom of a drawer and wondered what to do with them ;-)....
@Daniel
For now, I only ordered the regular 3 pieces batch from OSH; there's one unpopulated card left, the two others acted as prototypes...The total amount for that batch was 45�, so a card price is 15�. Including EPROM, all the components and shipping costs, I guess a total amount of ~30�...
There's no problem for me to burn your own SYSEX : you've just to send me the list of the patches you want to be included in the EPROM ;-)...
I don't plan to design cards for other machines, as long as I don't own them ;-)...Maybe later, I'll cogit about an Arduino/SD Card interface for my DX7...
@grant
Yes, I noticed the existence of cards using PCB traces for contact...the thickness of the PCB sold by OSH seem to be satisfactory, I didn't encounter problems of bad contact...Of course, it's necessary to see in duration after many insertions/extractions....I can't tell, it works perfectly for now !
Of course I would be glad to make the board available on OSH; I'll see how it works.
Chris.
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Félicitations Christophe! Cool stuff. I have a DX7-II so I won't order one (DX7 to DX7-II cartridge adapters are very rare and insanely expensive). One suggestion, it would greatly improve usability if you used hex rotary switches with knobs instead of DIP switches. Something like this:  -- Antoine
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Well done, Christophe.? I have many ideas like that one, but they rarely end up actually getting built :)
I agree with Antoine - DIP switches aren't ideal, not only for ergonomics but because they are not normally rated for frequent use.?
For example, the Yamaha WX5 uses them to set options (on boot) but it advises in the manual that they are not meant to be changed frequently.? DIP switches are notorious for failing, if they're used a lot.
Maybe you could break out the switching section to a separate board, e.g. via a header and an optional IDC cable, so people could provide their own solution - that's the easy bit.? I think most of us could handle doing that, with a bit of advice from other members.
I only have a TX7, and they didn't provide a cartridge slot, so I can't use one, unfortunately.? It would be nice though.? I've debated whether it's worth the effort to design an Arduino based sysex librarian module to send a bank to it, based on Bank Select messages, for example.?? Maybe one day...
FWIW, I've (hopefully) attached a bank I've made with my favourite Piano, EP and Clav sounds from the official 1a-4b DX7 cartridges, plus a few from another source.? I cheated a bit and used some of the cartridge guitar patches too, because some make quite nice clavs, to my ear.
Andy
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Hi Miks,
Thanks, I'll consider doing this !
Chris
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Hi Antoine & Andy,
thanks for the suggestion !
Of course a rotary switch would have been more reliable ( and more professional-looking ;-), but the DIP switches was cheaper and during construction, I kept in mind the use of the components I already had, like EPROM and DIP switches ;-)))
But it's an excellent idea, and I'll dig in it ! Also the use of a separate board could be a huge ergonomic improvement.
OK, there's still some work to do and stuff to play with !
Chris
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Maybe this is not problem IMHO, as such card with 4096 or 8192 patches and limited possibility to reprogram (becauser most of potential users have no access to and not enough knowledge about EPROM programmers) can be inside instrument all the time, like glued :-)
When there’s a need for more sounds, there’s still internal RAM and SysEx communication.
Daniel Forro
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Thank you for posting this. As Daniel has mentioned there is perhaps a large amount of pent up demand for something like this. Is there no issue with using the PCB traces as contacts? I know this has been done in the 80's and 90's but it seems all the recent attempts (even here on this group) have failed to achieve popular success because of board thickness or some other issue making them unreliable. I hope yours does work.??
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I would like a bare PCB so I can build one out of parts I already have, but alas I have a DX7S which is also not the exact same cartridge slot as the mark I.
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Good idea :-)
At the Yamaha forums the runner of "Sector101" is known as member 'shadowmask' - as you can see he uses such kind of rotary switch too - as well as with his Waveblade card... which is very comfortable to use.
This is what the Datablade/Waveblade cards looks:
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On Sun, 17 Sep 2017, strangemike1000@... [YamahaDX] wrote: At the Yamaha forums the runner of "Sector101" is known as member 'shadowmask' - as you can see he uses such kind of rotary switch too - as well
as with his Waveblade card... which is very comfortable to use.
This is what the Datablade/Waveblade cards looks:
I own such a card for my Yamaha V50. Very nice. -- MT
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Hi
Yes, rotatory hexa switches seem to be the ideal solution...the drawback is the price of such a component compared to cheap DIP switches...
Furthermore, one of the additional benefits of DIP switches is the possibility to substitute the not often available 27C801 for a smaller one ( eg 27C512 ) as the pinouts are quite compatible; you just have to set one of the highest bit switch ON to supply power to the chip.
Anyway, I'll work on a design embedding 2 rotatory switches, it's not huge work ;-)...
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Considering what Daniel very judiciously said, the card is not intended to be often extracted out of its slot, so a loss of contact is not expected in a even long time of use.
Chris
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The work of Sector101 is muuuuuch more professional than mine....I can't compete :-)
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Hi Ramiro !
What are you interested in ? Bare PCB ? EPROM ? Complete kit ?
Chris
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Hi & tks for answer
Well I don't know to much about that? What I looking for is? Rom card just ready for load more Sysex Sounds to my ?dx7 ?You know better? I hope you understand?
Tks
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Hi
Well, I inquired about shipping costs for USA, they are rather prohibitive...Including them, I think a complete card cost would be at least 50� ( ~ 60$ ) :-((
Chris
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We have a similar issue when sending packages from the US overseas.? This is why I mentioned the direct from OSH Park alternative as shipping from China is so inexpensive. Anyway, I am also interested in a bare PCB or kit.
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Michael Whocares
AndyHornBlower