Some points:
- you talk about subfolders. Makes me confused, are you actually talking about new files? Folders in my world is where you store several files (example: you can setup the 702 to create a folder every day). Not picking, just confused.
- the 702 can be setup to create a new file when an error is encountered (or to stop). I think your SD card is faulty or too slow, the 702 then gets a write error and faithfully immediately creates a new file. Best solution is to remove the problem creating the error, in my world most suspicious unit is the memory card.
- me thinks you have a bad SD card. There are some ways to test it on the 702, format first. Then run the speed test. Then setup the 702 to stop on error and simply start recording silence. If it runs to completion (full card) it is probably OK. To save time and increase confidence run at 96/24 for the test, or maybe even 192/24 getting a healthy margin for too slow card. It should run without fault at 192/24.
- immediately get a firewire cable that does not transfer power! I made mine from a 6pin/4 pin converter together with the right cable. Reason is that the firewire contact is a flawed design (not Sound Devices fault, it is the standard that was wrong from the beginning), you can push it in upside down with a bit of force. This may hurt your unit, and a 702 is too expensive to risk. Good idea for all units that does not draw firewire power (obviously there the power pins are needed).
Gunnar