Take off the bottom cover and locate R601 through R605 (on the Rev D board
these five resistors are right by a custom Yamaha LSI chip labelled
YDC121-E.). Only R601 through R604 determine the type of drive, and I
don't yet know what R605 is for, maybe determines SCSI/IDE or maybe buffer
size, who knows. Anyway on the 4416S it is absent, and when I tried
placing a resistor there, it had no impact on functionatlity of my drive.

Anyway, to get back to the upgrade process, on the 2216E only R601 and
R603, and possibly R605 should be present. If this is not the case, then
don't proceed with this approach! It's designed for a 2216E with R601 and
R603 present, and R602 and R604 absent. Carefully unsolder R601, a
zero-ohm resistor that acts as a jumper. With it unsoldered and nothing
more done, you could use it as an unreleased product, the 4214 which would
do 4X burns and 2X rewrites. But then your burner software might not
recognize the drive in this state. If you want both compatibility with
all current burner software and better rewrite speed then go ahead and
solder the same resistor you just removed back in as R604. It's a
daunting task since it's one of the extremely small surface-mount kind.
It may be helpful to hold it in place with a toothpick as you carefully
heat each side, otherwise the teeny resistor can get stuck to the tip of
the iron rather than staying on the board. Don't use very much heat as
the copper pads may come up unexpectedly on you.

Once R604 is soldered in, upon boot it should now be recognized as a
4416E. No need to re-flash anything since the 4416 uses the EXACT same
firmware as the 2216! Again I don't know if it will work since the
firmware may expect there to be a 2 meg buffer when the drive is a 4416 or
4216. But if you're the experimenting kind, maybe it's worth a gamble.

I should make a disclaimer that working with surface mount components is
tricky at best. If you don't have any experience in the area yet, find a
dead CD-ROM drive, hard drive, or some other component with surface-mount
components on it and practice. You don't want to screw up a burner with a
bad solder job!

I found all this out while trying to upgrade my 4416 to be a 6416 or 8424.
Unfortunately it looks like it's not possible since the firmware is
really different, and probably there's some fundamental internal
difference as well, but at least hopefully this info benefits some 2216E
owner out there. BTW, was there ever a 2216S? The firmware supports it,
but I haven't ever seen one sold anywhere. Just to recap, here's the
three selections that work on my 4416 burner, out of the 16 possible
combinations of R601 through R604:

• R601 and R603: Comes up as a 2216
• Only R603: Comes up as a 4216
• R603 and R604: Comes up as a 4416

All other combinations of resistors come up with the two front LEDs
flashing red continuously, and the drive not being recognized at all.
This does not damage the unit in any way, and after changing to one of the
above three supported settings the unit again works fine. Note that with
these settings on my drive it didn't matter if R605 was installed or not.
If anyone finds out what this jumper is for, please let me know.

If anyone tests this out and has success converting a 2216 to a 4216 or
4416, please email and tell me. Also if anyone out there has a 6416 or
8424 and doens't mind popping the cover just to look at the resistor
arrangement, I'd be very interested in learning how those drives are
configured. They should probably have the same five resistors (R601
through R605), but with different combinations jumpered than with the
older drives.