Replacing the EPROMs in an Ensoniq VFX series synthesizer

These instructions were written based on the SD-1, but the process is nearly identical for the VFX and VFX-SD.

First, remove the four allen screws holding the top cover on and open the synthesizer. There are a bunch of ribbon cables packed in there, so it's difficult to see the EPROMs straight away.

inside the SD-1, a wide shot

Figure 1. A wide view of the inside of the Ensoniq SD-1, showing a mess of ribbon cables.

The OS EPROM chips both carry white stickers that indicate which OS version they have "burned" into them. In order to see the OS EPROMs, one must remove the ribbon cable that connects to the main board and runs to the keyboard.

a closer view of the ribbon cable mess inside the SD-1

Figure 2. A closer view of the ribbon cables, with the ribbon for the keyboard in the center.

inside the SD-1, a wide shot

Figure 3. With the keyboard ribbon cable removed, one can see the OS EPROM chips. Note the white stickers on the chips.

Using a good IC-puller tool, grip one of the EPROMs tightly. With care, pull upward to remove the EPROM. The chip may need a bit of wiggling from side-to-side in order to get it free from the socket, but be careful not to wriggle too forcefully and bend the pins.

gripping an EPROM with an IC-puller

Figure 4. Gripping an EPROM with an IC-puller tool.

Repeat the process for the other EPROM chip.

When the EPROM chips are free, replace them with the EPROMs that have the desired OS version. When inserting the EPROM chips into the sockets, be careful that the pins align with the socket holes well, or the pins may bend as they are pushed into the socket.

OS version 4.10 is the last release from Ensoniq.