NUCplus4 Assembly/Installation

NUCplus4 Brief Description...

This daughter board is meant to expand the basic 576NUC+ miniature Atari computer system with a multitude of new abilities. Four at any given time to be exact. Go here for more INFO.

Assembly...

This is pretty much a through-hole board in most regards, with the only exceptions being the the Push-Push SD Card socket and the optional FujiNet Module's ESP-32 which has a castellated surface mount configuration.

So just like most such boards, it's normal to start out with the low profile components first such as the resistors followed by the capacitors, and then move into the larger ones. I'm not going to go into a lot of detail regarding this, since I'll be assuming that whoever undertakes this project from a DIY aspect already knows how to assemble and solder a PCB.

Let's get into the more critical stuff, with the first being the installation of the pin-to-pin male headers for piggybacking the PLDs on the 576NUC+ board.

In order for the NUCplus4 daughter board to sit parallel to the 576NUC+ board, these pin-to-pin headers need to be absolutely flush as possible with the underside of the NUCplus4 PCB and perpendicular to it (specifically the shoulder on the pins should be flush with the PCB). To insure perpendicularity, temporarily plugging in one machine pin socket will maintain proper alignment. These will get removed after the pin headers have been soldered in place on the top side of the PCB.

Here's what that'll look like.

After soldering the male pin headers, trim all the protruding pins inside the IC socket footprints as flush as you can with the top of the board (good quality side cutters should be used for this).

Now insert the sockets for the PLDs, and after removing the temporary alignment socket on the bottom side, solder those in as well. This will be a bit tricky, and a soldering iron with a long skinny conical tip really helps.

Now you will be ready to solder in all the remaining sockets and headers. I suggest doing it in this order, so that you don't block your access.

1. Machine Pin socket for U1 (make sure U1 is pushed all the way in with its shoulder slightly protruding from the bottom of the board).
   
2. Now insert and solder all the rest of the sockets.
   
3. Insert SIO extended male pin header (P1) from the bottom side of the board and solder it from the top.
   
4. Insert remaining headers and components and solder in place. Wherever possible insert devices (Pico Module and FujiNet Module) with their male pin headers in place to hold alignment of female headers before soldering.
   

With all the soldering done, it's now time to install the necessary number of piggyback machine pin sockets for the PLDs (2 sockets each) and U1 (3 sockets). The final stack up should look like this.

The completed assembled board should look like this when you are done.

Three chips will need to get moved (U3 SRAM, U4 MMU, U5 EMMU) from the 576NUC+ to the NUCplus4. The EMMU will need to be re-flashed with the 1024K jed.

There's a modification that needs to happen before plugging the NUCplus4 into the 576NUC+, and that has to do with the top clearance of the 576NUC+'s 8-Pin DIN A/V jack. It needs to have some of the plastic filed off (mainly the bump towards the rear).

It'll also help to trim off the pins on the rear most row of the PLD socket with side cutters after soldering.

Plug in all the required chips after flashing any that require it, and be sure to re-flash the embedded TK-II chip in the 576NUC+ with the NUCplus4 specific firmware (consult the Datasheet for more information about this)

You should now be good to go.

- Michael