i turn on my jx-305, the pattern name is still there, but there is no sound. i switch to my next pattern, the sceen goes blank. i turn it off then on, i see arrows before the startup screen is displayed.
i panicked, and wanted to load defaults and backed up everything on the card which has the older versions of data (which means that i could have been able to save the older versions, if i used a new card)
i load the factory preset, all's ok, except for my data.
i did not get any error messages, nor did i turn the power off during any form of saving.
the synth is right in from of my pc monitor- could this be the problem? what i mean is that does a monitor emit magnetic signals and will the card or flash memory be damaged by magnetic signals?

I've had a similar problem with my MC505 - Please refer to a recent posting. I've reinitialized (see manual) my device after saving my patterns on a smart media card. I do not use a computer when composing so I cannot say it is the monitor. My current feeling is the internal battery must be frizzing. So far though, it hasn't repeated the symptom. I wish I could tell you definitively that is the problem, but until I can get some one to discuss this who knows, I go with the conspiracy theory ie planned obsolencence.

thanks. that's what i did too. but i did something stupid witht he smart card (read my post again).

did you also see the arrows at startup?

so, you were able to retreive your data?

I didn't have a formatted smart card handy - I used the one from my SP202 after saving the samples to mini disc. I then formatted the card on the MC505, initiated back up to card (all) then re initialized MC505 and reloaded the back up to MC505. It worked overnight then in the morning, the sounds (patches)changed again. So I reinitialized again and reloaded backup (the whole thing) and I was still having the same thing happen. So I reinitialized just the patches this time and it has seemed to work without problem since (knock on wood). I am still trying to figure why this happened so I can take care of it so it won't again. As far as the arrows goes - I've seen them before, but not under the previously described circumstance. I think it was when I had powered down and up in a hurry (trying to erase the temporary user pattern in a hurry early on in my ownership). Do you still have this problem?

not any more, but i'm still pissed off. thanks anyway.

A friend of mine suggests that the Roland products with similar synth engines like yours and mine had a computer virus which knocked them out around this time. Far fetched or what? I wonder if anyone else's went down.