NBM CD Instructions Top Loader

Step 1: Screwmageddon

Tools Needed: Phillips Screwdriver and something to keep the screws sorted.

There are 4 screws that hold the case together and about 500 more screws inside the system.  Once you remove the top lid, carefully remove the ribbon cable that connects the drive to the mother board.  This cable is pretty fragile and repeated disconnecting and reconnecting can and will damage it.

The second pic shows these 2 black plastic riser things.  If you have a metal shield like the one in the pic, you will have 4 of these when you remove the controller board.  Make sure you don’t lose them.  All the other pics show cables that need to be disconnected.  Don’t forget the long yellow one that goes from the AV/Power board to the controller board.  Also, there are 2 black screws that hold the AV board to the back of the case.  If you notice you cant remove the AV board, check to make sure you removed those 2 black screws.

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 Step 2: Bios Disable/Prep

Tools Needed: Soldering Iron, solder wick, 2pc wire.

Now that you have survived Screwmegeddon, the next step is to disable the onboard Bios.  The pic below shows where we’ll be working next.  The MASK1 location chip is labeled TOP-SP1.  That’s what we’ll be disabling.


Take some of your solder wick and lift pins 10 and 12 from the motherboard.  Do it gently, if you are uncomfortable with this portion, please consider sending your system to someone who is.


Solder a small wire from the lifted Pin 10 to Pin 21 of the chip.  This will disable the on-board bios.  Take your longer wire and solder it to the Pin 12′s pad.  Remember Pin 12 has been lifted off the board, just solder the wire to the pad under that leg.


Step 3: NBM Mounting

Tools Needed: Soldering Iron, electrical tape

OK, now that the bios is disabled it’s time to mount the NBM.  First you need to make sure that the ribbon cable is attached to the NBM like the pic below.  The cable should be coming out of the top of the header, not the bottom.  When I ship these, I will have it already connected the correct way.


Place the NBM on top of the Motorola 68000 labeled as CPU1 on the motherboard.  Make sure to align the board correctly to the top of the 68k chip.  Notice how you can see the ‘M’ logo.  It does take a bit of pressure to push this on the CPU, make sure all sides of the PLCC socket are even to the motherboard.  If you look in the hole and you see an uneven gap, remove and re-position the NBM until there is no unevenness. Just a note, there are 2 different layouts of the NeoCD’s 68k.  The majority of the systems have this layout, but there is another version that has the 68k rotated 90 degrees counter clockwise.


Now solder the OE cable you attached to the Pad of Pin 12 of the original bios.  And fold the ribbon cable like the second photo.  If you have one of the counterclockwise 68k systems, you will have to position the cable in a way that the end of the cable is in the same position as pictured here.  The cable will still reach.  You can fold this cable without a problem, it will not hurt it.




Step 4 Testing:

Tools needed: Electrical tape

So, now we need to make sure things are good to go.  Get your heavy metal shield or that plastic rust colored shield and put some electrical tape over the section showed in the pics.  Even the plastic looking shield need to have this.  It is painted with a conductive paint and you dont want to sit the board on top of it without protection. Put the shield back on top of the motherboard and pull the ribbon cable through that hole.

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Now before you spend 2 hours putting all the screws back in the system, now it’s a good time for a dry run.  Place the AV and Controller board back in place and plug in all the cables.  Remember to put the black spacers back on the controller board.  You don’t need to put the CD drive back on just yet.  We want to make sure the system is seeing the new bios.  If you turn on your system, and it boots, you’re good to go!

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Step 5: Reassembly

Tools Needed: Double Sided Tape, Screwdriver.

Since the dry run went fine, remove the AV and Controller Board and screw down the motherboard to the case.  It’s a good idea to leave the screws a little loose to make sure all the holes align with the shield and motherboard.  Then when all screws are in, tighten them up.  Once the MB is secure, screw the AV and Controller Board back.  Remember to put those black controller spacers back and that long yellow cable.  Please be careful when putting the drive ribbon cable back in.

When you mount the NBM to the top of the shield, make sure no part of the bottom of the PCB is touching metal.  We put some electrical tape under it earlier, just double check to make sure its covering the entire space where the NBM will live.  MAKE SURE the NBM is as far over to the right of the system as possible, the ribbon cable should be touching the right side of the hole.  See the pic below.   If you mount it too far over to the left, the CD drive PCB will hit it.  I will have a piece of double sided tape already stuck to the bottom of the NBM.



Optional: USB2Neo Switch

The Universe Bios has a feature that allows you to use the USB2Neo adapter.  The NeoBiosMasta does not have this feature installed by default and is hard wired to only use the standard CD Universe Bios.  If you have a USB2Neo you will need to remove the jumper from that bridges pins 1 and 2, install a switch and a 10k Ohm resister on postion R1.