I had an idea for a low-profile, swappable jumper pak / expansion pak for N64 portables. This would give builders the best of both worlds: a low power jumper pak for the vast majority of the library, and the ability to plug in the power-hungry expansion pak when needed for Majora, DK64, and Perfect Dark.
I whipped up the boards in an evening, and they arrived a week later.
Vterm / Vref are generated on the module (a separate Vterm LDO is still needed on the mobo for CCtlPgm and clockgen). Eventually the clockgen could be moved onto this module.
Installation:
Some very interesting Summercart64 errors...
I thought maybe I hadn't carved out enough of the disconnected Rambus channel, so I pulled everything off and did some more surgery.
Then I went ahead and did an Akira method, just to make sure I didn't fry anything.
Hmm, that worked...
I reinstalled a fresh slot (with some jumpers for the pads that got lost along the way) and converted the expansion card to a jumper card.
But still, nothing!
Things I tried during troubleshooting:
Perhaps changing the termination or CCtlPgm resistor values could compensate for the impedance discontinuity the pin headers present? That's getting into really iffy territory though.
Despite it not working, the photos were pretty, so I figured I'd share! If I find a more promising connector I might revisit this idea.
I whipped up the boards in an evening, and they arrived a week later.
Vterm / Vref are generated on the module (a separate Vterm LDO is still needed on the mobo for CCtlPgm and clockgen). Eventually the clockgen could be moved onto this module.
Installation:
Some very interesting Summercart64 errors...
I thought maybe I hadn't carved out enough of the disconnected Rambus channel, so I pulled everything off and did some more surgery.
Then I went ahead and did an Akira method, just to make sure I didn't fry anything.
Hmm, that worked...
I reinstalled a fresh slot (with some jumpers for the pads that got lost along the way) and converted the expansion card to a jumper card.
But still, nothing!
Things I tried during troubleshooting:
- Validated Sin/Sout chain was behaving as expected
- Confirmed continuity between RDRAM #1 and the pads on the card
- Confirmed all termination resistors were connected
- Measured VDD, Vterm, Vref,
- Measured TXCLK, looked fine
- Tried running everything from the stock Vterm LDO
- Tried running a stock N64 from the ramcard LDO (worked fine)
- Tried some CCtlPgm shenanigans (powering resistor from card, from separate LDO, etc)
- Tried adding GND plane over the CCtlPgm trace on a stock N64 in case turning it into a stripline with the flex was causing issues (nope)
- Tried adding more bulk caps on card
- Tried removing some bulk caps on card
Perhaps changing the termination or CCtlPgm resistor values could compensate for the impedance discontinuity the pin headers present? That's getting into really iffy territory though.
Despite it not working, the photos were pretty, so I figured I'd share! If I find a more promising connector I might revisit this idea.
Last edited:
