Anyway, I guess the final question for the Forum members comes down to------ does anyone have a service/shop manual for any of these units? The 2160a, 513, 515, 537, 557--- they no doubt all have the very same power supply configuration so a manual for one would be just as good as for any of the other units in this series.
If anyone does, look in there and see if it gives any clues to the identity for:
Have you seen this section of my help file on Hardware Replacement & Upgrade?.I think they're still in business although I haven't contacted them myself in awhile.
SuperFW 727V was a one-time special case where Funai was creating a user update for the 515 and decided to help us out by making it applicable to the previous two SATA-based units, 2160A and 513, so they wrote the FW to apply to all three.
Normally, if you try to install Funai FW not written for a specific model, the FW disc runs and runs and eventually says it can't be installed, but it's very scary during that "WTHishappening" phase! I tested this one time and do not recommend it if you have a weak heart... YMMDefinitelyV!