But after many years, the capacity of the battery become insufficient to ensure a proper backup of the SRAM when the Prophet VS is powered off. Worse, when the lithium battery is very 'out of date', it is possible to observe a leak of acid liquid witch spreads off the circuit board. It could be really catastrophic for the printed board.
So, since a few month, I create nonvolatile memory replacement for the standard SRAM in 2, 8, 16 or 32 Kbytes.
I decided to create a special edition for the Prohet VS. Special because I had to respect a protection against the potentially corruption of the data by writing wrong values at wrong addresses at the power on of the synthesizer. I had to create a special circuit board for that and replace the original SRAM with the new nonvolatile SRAM.
First, the main board of the prophet VS :
|A very classical 68000 board!|
|Without SRAMs and without the battery.|
|A main board up to date !|
No! You don't dream, this connectors will allow you to select ONE of the FOUR bank now availables!!!
Yes, it is possible because the original SRAM are 8 Kbytes capacity, but the new one have a 32 Kbytes capacity.
And the result :
|One more improvement!|
- No more battery.
- 400 programm capacity, into nonvolatile SRAM.
- Two ELD5530, my CEM5530 replacement.
If it continues I will rebuild this Prophet VS by myself !!!
And, does it work? Yes, of course!
I have to reload my patches into one of the four ram bank, and to find a solution to select the four banks now availables. I don't have decided yet how to do that. I want to conserve the original look of my VS, so perhaps a kind of 'programmer' like the PG200 of the JX3P...