Elka Synthex

An open Elka Synthex.

The Elka Synthex ...

Schematic issues

• 5870 chip 3C-5 connects to 2F-5, probably called XF1 (not F1, which is another signal)
• 5870 2F-6 connects to PHI2 out of 6502, pin 39
• 5870 3H-10 connects to 3I-7
• 5870 3H-12 connects to 3I-6
• 5818 chips 1,2, bank sw 1 is on D0, Port is on D5, so order is opposite what schem shows
• 5818 chips 3,4 prog 0 is on D0, prog 5 is on D5, same issue as above
• 5818 chips 5,6 prog 6 is on D0, Pink is on D5, same issue as above
• Osc2 Glide/Port Switch is connected to CST5812 IC3, which is for Osc1 (fixed in code)
• Osc1 Glide/Port Switch is connected to CST5812 IC1, which is for Osc2 (fixed in code)
• Connections from pots to CST5811 are very different from what schematic shows.
• 5870 shows SRAM chips 2L and 2M powered by +5V, but they are powered by +5E.
• 5890 6850 UART chip select polarities are shown wrong: pin 9 is active low, pin 8 is active high
• 5860 has 5P pins 5,6,7 twice. Chorus Upper section should be 5P 1,2,3 instead
• 5870 shows op amp 5Nb 5,6,7 twice
• 5870 shows pin 16 of 4051 IC's 4M, 4N, 4P, 5M, 5P connected to +15V. They are connected to +5V.
• 5850 board chip 1B and 1A pin 4 on the bottom row should be pin 2. Pin 4 is an input.
• PSU board 1000 μF electrolytic capacitors just after the rectifier are 10000 μF in reality.
• PSU board zener diode 19 on the 5V rail (just before TIC110) should be the other way around.

Other info

• Front panel boards data bus wires follow the resistor color code, so the D4 connections use yellow wire, D2 use red, etc.

External links

• Elka Synthex, Wikipedia
• Elka Synthex, Vintage Synth Explorer

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