I had a DX7s that crapped out on me a few years back, I think from a power surge.  Turned out the main board was fried, and the cost to replace it was astronomical, not to mention that the part would have taken weeks to come over on a slow boat from Japan.  I ended up listing it on eBay, and some guy who was doing a home-made synth thing bought it for his project, so it wasn't a total waste.  I have seen replacement DX7's on Craigslist as low as $200, so you might be better off picking up another one and saving/selling your current one for parts.  Good luck with it, as they are nice boards when they work!

leapinlizard
I had a DX7s that crapped out on me a few years back, I think from a power surge.  Turned out the main board was fried, and the cost to replace it was astronomical, not to mention that the part would have taken weeks to come over on a slow boat from Japan.  I ended up listing it on eBay, and some guy who was doing a home-made synth thing bought it for his project, so it wasn't a total waste.  I have seen replacement DX7's on Craigslist as low as $200, so you might be better off picking up another one and saving/selling your current one for parts.  Good luck with it, as they are nice boards when they work!

Looking at some of the prices being charged for the parts I could probably make some decent dough just selling it a piece at a time. lol

I've been through the battery issue myself. I think we sorted out the DX7 by removing the old battery, soldering in a new holder for the battery (so it can be replaced easier next time) and putting in a new battery. I think we needed to perform a full reset of the DX7 afterwards by pressing a key combination (I downloaded the PDF manual for this).
 
 
The battery is a total pain to change. Yup I use FM8 nowadays with the ROMs.

To be quite frank I don't know how anyone programmed patches on those things....FM synthesis is complicated enough without having to negotiate everything on a small screen like that...lol!
 
I have FM8 though and it is marvelous, they've really put loads of thought into that interface. I don't think I would have had the patience to learn FM without it. I would like a real DX7 though. 

CakeAlexS
I've been through the battery issue myself. I think we sorted out the DX7 by removing the old battery, soldering in a new holder for the battery (so it can be replaced easier next time) and putting in a new battery. I think we needed to perform a full reset of the DX7 afterwards by pressing a key combination (I downloaded the PDF manual for this).
 
 
The battery is a total pain to change. Yup I use FM8 nowadays with the ROMs.

Funnily enough that battery likely won't need to be replaced for another 20 years. Heh.
 

sharke
To be quite frank I don't know how anyone programmed patches on those things....FM synthesis is complicated enough without having to negotiate everything on a small screen like that...lol!
 
I have FM8 though and it is marvelous, they've really put loads of thought into that interface. I don't think I would have had the patience to learn FM without it. I would like a real DX7 though. 

One of the vids I was watching earlier showed an LCD that would show a graphic of the wave thingie of what you had created. I thought "cool"! Then I looked at mine and realized it didn't have that screen. D'oh!
 
First thing I did when I first hooked it up years ago was play the Beverly Hills Cop theme like a dorkoid. I found out much later that it wasn't even a DX-7 used for that part... at least the lead line wasn't.

Beepster
 
Funnily enough that battery likely won't need to be replaced for another 20 years. Heh.

Which will be the next time I will probably end up switching it on.
 

Don't do anything until the battery is replaced. If it's bad, your memory will always be scrambled as soon as you power down, and it will power up in some unpredictable state where anything is possible.