Vintage Synth Explorer Forums

Hello,

I've got an Ensoniq VFX that I replaced the OS EPROMs upgrading the OS from 1.7 to 2.10 my problem is that with the new OS installed I get weird crackling sounds that sound like they were run through a delay circuit with the regen cranked way up, in that they start out relative minor and build to drown out the program audio. Sometimes the volume slider will drop the levels on this distortion and sometimes it has no control over it even though it does drop the program level. Power supply voltages are all good and if I reinstall the old OS EPROMs things are back to normal. The only other thing wrong with the unit is that MIDI out doesn't work due to U2 (Hex buffer) being bad between the UART and the MIDI out connector. Everything else with the new OS seems to be fine. Anybody got any ideas (software, hardware????)

What was the source of the new OS ROMs? That would be my first thought, that the ROMs are corrupted somehow.

I bought them off eBay from a seller who has a number of similar EPROMs listed for different synths. To be fair the seller has offered to take them back and give me a refund. I would expect if there was a corruption of the OS that they wouldn't boot in the machine at all; at least that's my experience back in the day of DOS on floppy disks.

I'm an EE very familiar with software so I also wonder how the OS ROM could cause the problem, but as you stated, the old ROMs exhibit no issues. So it's the only thing that's changed, right?

I'd look for release notes for the various OSes and see if anything comes up as a red flag.



BTW is this a VFX or a VFX-SD. I see the two share some OSes and others are only for one or the other.

It is a VFX. I don't see anything in the software notes that jump's out at me. It does state that all VFXs should be upgraded to OS 2.00 or above.