ElkaTwin 61 MIDI kit retrofit Vitalka Custom Installation manual
Important:
This retrofit required to isolate the ground bus from key contacts (polyamide tape for example). It is important to allow switching POLY synth keys from the MIDI interface. It probably can create more humming noise after.
Installation:
Select the right place to mount the LED, DIN5 MIDI connector and button on your synth (on the back panel near jacks for example). PCB can be mounted under the keyboard on the left side.
Drill holes and try to mount it before soldering wires.
Drill dimensions:
For PCB drill holes 3.5mm.
MIDI jack (DIN5) = 18mm.
LED holder = 6mm.
Push button = 12.5-13mm.
Be careful with drilling hole for button, it have so small range to get hole too big.
Board dimensions and distance between screws:
Dimensions 105x90mm. Height 14mm with inserted connectors.
Holes diameter 3.5mm. Distance between holes 94x78mm.
Do not allow the board to bend, it can break the board.
All ribbon cables are 90cm. long, enough for placing all connections and you can cut extra length.
Panic button is not included in the kit. In case of panic - enough turn off and turn on the synth. If you prefer to install it part number is E-Switch RP3502MABLK
Find at bottom side of PCB solder jumpers LJ5, LJ7, LJ8 and close them with solder.
The next picture shows the pinout for 8 wire ribbon cable and pin number of wires:
Same pinout you can find on bottom side of the PCB.
(7) V+ and (8) GND should be soldered on the next points:
This picture shown first (1) pin/wire on all connectors:
After soldering 8pin connector wires, time to soldering wires for key contacts springs solder points.
Upper group connectors is for BASS part, downer is for POLY part of keyboard.
Board pinout and MIDI note for BASS:
For POLY section:
Some explaining to table: Bus 1 = B1, Bus 2 = B2, Bus 3 = B3, Bus 4 = B4 this busses should be connected to same busses on Elka. See schematic for details.
B1 and B2 is for BASS sections at first two octaves (counts from left to right).
B3 is for second, B4 is for third, fourth and fifth octaves on POLY section.
Solder wires to common buses and every key contact spring.
You can see that on Elka schematic notes starts reversed - from right to left. Ignore it.
So, looks like installation finished. Now time to explain how set MIDI channel. This is what you need to know for starting use this retrofit.
To teach the MIDI channel, - stop all MIDI traffic. Push the black button (LEARN) LED will blink two times and stay ON to wait for MIDI messages. When messages are received LED will blink five times and turn OFF and then will ON with every NOTE ON messages on the selected channel. Now the channel saved to memory and not changed before will be rewritten.
One small important thing - use hot glue for fix inserted connectors for protect from disconnection them during vibration when you ride on tour. Also, fix wires strong. Do not leave them holding only on soldering joints.