Another exercise in extreme cost-downing. This time, it's an attempt to make the most minimalist yet still functional Nintendo 64 RGB amp. This is accomplished in only eight tiny annoying-to-solder parts.
Circuit is entirely analog so you only get the Gerbers.
Virtually the same as Tzorri Mahm's board, but with the following differences:
- The 47pF caps on the output lines have been removed. The THS7374 datasheet says these are there to prevent "ringing" interference, but they are not necessary for proper functionality.
- No ferrite bead on the power supply line.
- No power stabilization caps except for the one required by the THS7374.
- No lowpass filter enable pad. Sorry to all five people who use that feature.
- 0603 components have been changed to smaller and cheaper 0403s where safe to do so.
- 75 ohm current limiting resistors on the RGB outputs are now grouped together into a single 1206 resistor array.
- As a result of a lot of things being left off the board, the board has a somewhat smaller footprint, but is slightly longer.
See readmes in Gerber directories for BoM and component placement information.
The four solderpoints at the end of the board are, in this order: R, G, B, CSYNC.
On NUS-CPU-01 through NUS-CPU-03 boards, the CSYNC pin on the multi-out will be driven by the N64. If you'd prefer to have the amp board drive it, you need to remove these components: R1 R14 R15 R16 C22. If those components are not populated, then the board has no CSYNC and you will need to install the CSYNC wire.
On NUS-CPU-04 boards, the components that normally drive CSYNC will not be on the board.
For the aforementioned boards, installation requires three or four wires:
- R -> R8
- G -> R9
- B -> R10
- If CSYNC needed, CSYNC -> R16
NUS-CPU-05 through NUS-CPU-09 boards need a separate DAC to work with this mod. Nintendo integrated NTSC video encoding onto a single chip (AVDC-NUS and MAV-NUS) so there are no more analog RGB outputs. You will either need to use an external DAC or try a different mod (Tim Worthington's N64RGB or some shitty version of it) to get RGB out of those systems.
It's recommended, but not required, to put insulating material under the PCB before you solder it in.
After installation, test everything and make sure it works. If you get RGB output, hooray for you. If not, something is wrong.
It's very important to check the temperature of the THS7374 amp when the circuit is running. If it's blistering hot, then there's a short circuit on one of the outputs, most likely the CSYNC pin. Remedy this issue immediately to limit damage to the amp (and your N64).
Public domain