M.I.D.I. to CV/GATE

An other project in progress :

M.I.D.I. to CV/GATE interface

• M.I.D.I. channels : 1 to 8 OR 9 to 16.
• GATE : 5V.
• CV : 4 x (0V to 5V) and 4 x (0V to 10V).
• CONNECTOR : 3,5mm jacks.

SRAM select command.

My system of SRAM bank selection in on the way...

This system selects one of the memory banks installed inside a synthesizer. It will remain outside the synthesizer and will be connected to the internal memory using a connector placed on the instrument case.

In addition, a MIDI connection will allow the automatic selection of the bank, in relation to the desired patch. So it will not be necessary to modify the synthesizer motherboard in any way.

This system makes it possible to manually modify the memory bank, as well as the MIDI channel for receiving the MIDI bank change information. The MIDI channel and the number of the last bank used will be saved.

this system should also be a better bank change solution for my Prophet VS, compared to the previous system :

THE NEWS

This last month, two prototypes were made. A circuit compatible with the 16550 UART and a self-saved 16 x 6116 SRAM circuit :

The 16550 compatible UART is partially tested. Its usb interface is fully functional. This '16550' offers two identical serial interfaces. One of them can be used in TTL or with a RS232C level converters as usual, the other is directly connected to the on board USB interface. It would be easier to communicate to vintage computer with this solution, as with my hold Z80 N8VEM board : 

On my N8VEM I haven't yet the 1,8432MHz oscillator, as in this picture.

The 16 x 6116 equivalent self-saved SRAM is tested. It's basically the same system as my previous self-saved 6116 solution : 

the hold version.

BUT, now it's possible to select ALL the sixteen 2Kb space. I work on an easy-to-use bank selector...

16 banks of internal 2Kb auto-backuped SRAM.

And now, the equivalent of 16 x 6116 auto-saved memories for your favorite vintage machine like :

• Alpha Juno 1-2
• Juno 106
• JX-3P
• MKS-30
• JX-8P
• JP-6
• TR707
• Prophet 600
• DW6000
• DW8000

and many others...

On the past, I developed a simple solution that had the disadvantage of only using part of the new memory component:

Very effective solution, for example inside a Roland JX-8P :

But, only 2Kb are used on the 32Kb that contains the new RAM.

So I decided to do a new version with an additionnal connector for the extra addresses selection :

The J1 connector will allow to select the memory bank using an external selection solution.

The other side of the board :

This board will be a little bigger than the previous version but still very closed to the original size of a 6116 SRAM chip :

Once this card will have been tested, it will remain to develop the board of the memory banks selection system.

And Now for Something Completely Different : Jean-Luc Van Den Heede

Je ne connais pas personnellement VDH, mais je l'ai souvent côtoyé entre 1982 et 1985 au lycée ou je préparais mon bac. Et non, VDH n'est pas surnommé VDH que dans le milieu de la voile. A Saint Jo. tout le monde le connaissait sous ce 'pseudonyme'.

Bien que pratiquant la voile, à l'occasion, je ne suis pas un fan des courses au large. Mais cette G.G.R., ce tour du monde à l'ancienne, sans instruments, sans assistance, ça n'est pas une course, c'est autre chose, il y a forcément du  Moitessier la-dedans.

A 73 ans, VDH ne fera plus de tour du monde à la voile. Celui-ci, son dernier, il l'a gagné. Alors je suis arrivé tôt à Olonne :

7h30.

j'ai longé les différents ports pour rejoindre l'entrée du chenal :

8h.

L'attente a commencé sous une pluie fournie mais pas suffisante pour décourager les spectateurs dont le nombre s'est mis à croître sans discontinuer :

9H.

Peu avant 10h, le voilier de VDH pointe sa proue, au loin :

Et enfin, la remontée triomphale jusqu'au port de plaisance :

Plus tard dans la matinée.

Quelles peuvent être les sensations dans un tel moment, quand on est conscient d'avoir réalisé quelque chose de grand?

Bravo Monsieur, merci et bon vent...

Restent en course au 29 janvier 2019:

• Mark Slats, parti se réfugier au sud du Golfe de Gascogne pour échapper à Gabriel, et qui risque d'écoper d'une pénalité... 29 janvier 17h : Mark Slats semble avoir changé d'avis et se dirige de nouveau vers Les Sables. 36h de pénalités qui seront ajoutés à son temps de course. A suivre...
• Uku Randmaa et Istvan Kopar qui se tirent la bourre au large du Brésil.
• Tapio Lehtinen qui devrait enfin réussir à passer le Horn d'ici quelques jours, toujours dans les temps de Robin Knox-Johnston.

Avec une pensée pour ceux qui ont du abandonner, notamment dans les mers du sud :

• Abhilash Tomy.
• Susie Goodall.
• Loïc Lepage.

Sans compter Philippe Péché avec qui la course en tête aurait pu être... plus disputée.

Et tous les autres...

UPDATE 1/02/2019

Je ne pouvais pas y être, alors j'ai suivi l'arrivée de Mark Slats en live sur les médias sociaux :

Superbe arrivée... Bravo!

The expanded Drumulator back home.

The customized Drumulator with the Wave-Rom switcher and the OS-Rom switcher boards...

Wave-Rom switcher board.

OS- Rom switcher board.

found his owner again and a new companion :

Nice team!

JX-8P Repair.

This time, I got a JX-8P in a mint condition apart from two voices that posed a problem with the VCF.

Pretty vintage machine!

After passing the test procedure, it was obvious that voices A and E posed a real VCF worry. In a first time, as I had the same kind of problem with a JX10, I thought I was in the same situation so I ordered two IR3R05 :

And placed them on two IC sockets :

Ok! And does it work better now? NO. Too simple!

No choice, I have to test the control voltage coming from the two ICs, CD4051 (IC44)  and the TL064 (IC51) :

I noticed that effectively, the voltage comming from the par C and D of the IC51 (TL064) didn't match the requierd values. So I replaced this two ICs, the TL064 (TL084 works fine in place of the original TL064) and the CD4051 (IC44). As I was there I also replaced the IC43 (CD4051) circuit which supplies the voltages control for the VCA part of the IR3R05 :

The three ICs on socket.

After this modifications, the voice E working good but, the voice A did not provide any sound. I had to go to the next step and use the oscilloscope to determine that the capacitor C88, whose role is to provide the sample and hold function, was in fact in short circuit with the ground. I nerver had this problem before with this kind of interface in a Roland hold synth! I replaced this capacitor with a new one in smt version. I soldered this 805 type capacitor on the other side of the board. After this last modification, all the voices were working very good : Yes!

Finally, troubleshoot this JX-8P was not very difficult, even though I have now two IR3R05 fully functionnal in stock. I will keep them preciously, just in case...

Inside this JX-8P (before my repairs) :

No dust, no mold, no rust and no... beast : absolutely perfect!

Not even blackish traces of heat on the power supply!

Good, but before reassembling the machine, there is again to take care of the backup of the static ram :

 
I decided to have no more problem with the backup battery. So I made a copy of my auto-saved SRAM :

It's a solution that works perfectly for a stand alone auto-saved replacement for the 6116 SRAM. I also have a version to replace the 62256 type SRAM. Before it's installed in the JX, I tested it with my EPROM programmer :

OK, it's time to put it in place :

Of course, no more battery is needed :-).

The internal patchs are reset at startup :

But, after copying the preset number one into the internal number one memory, and after restarting the JX, the patch number one is still present :

Voilà, a superb vintage synthesizer ready to play again for many years!