Step 1
Place the CoCo upside down and locate all the screw holes.There are 6 screws, two are always located under the stickers.

Figure 1a

Left side bottom

Right side

Just poke through the label sticker

Step 2
Carefully flip the unit over and remove to top shell. You should now be able to see some thing similar to figure 1b. I was suprised to not find a whole lot of shielding on top.

Step 3
remove the screw on both sides for the Power supply cage (figure 1c), and unplug the lead, unlike the CoCo 1 and 2, tandy actually put a decent plug, so there is no need to lable the wires

Step 4
You should now have the Power Supply disconnected. Carefully lift the Power supply straight up, and put it to one side .Careful to untwist the cord around the post.Now is a perfect time to inspect the PS to see if there are any burn (overheating) marks or leads that need to be re soldered. I recommend if you have the skill, to replace the 3 wires on the PS, because they can become stiff and brittle. Why risk a fire hazard for 20 Cents worth of wire and 3 blade leads. Also, if you can, replace the fuse with something a little more sturdy. If you can get a proper fuse holder and solder two wires to it. this can be tucked underneath the motherboard out of the way. if you get a socket type, just use a dremal or a drill to cut a small hole out the back.

If you are totaly removing the power suply, here is how the power cable snakes in the stand offs.

figure 1b

Figure 1c.

Keyboard Removal
Step 5
Now that the power supply is removed, and all the screws underneath, CAREFULLY flip the keyboard up and towards the back, there is a Mylar ribbon that just "slides" straight in to the connector on the Motherboard and over time this can become stiff and fragile. To remove it, Just pull straight up and gently rock it back and forth(figure 2a).

Figure 2a

figure 2b close up of conector

Before we actually remove the motherboard there is one thing to be aware of. The keyboard has Rubber rings on the standoffs, probably to absorb shock. Carefully remove these rings and place them in a cup. keep this cup to put in the motherboard screws and if you are removing the RF shild underneath, use this cups for the clip




















Part 3 Motherboard

Good news! we are almost there

Step 6
Now the the keyboard off, you will be ready to remove the Motherboard. Note the RGB monitor pins underneath the motherboard when you lye it on the bench.
Step 7
Remove the 4 Fastening screws that hold the motherboard in place.1 is located on the lower left hand side, below the Power supply , one is on the lower right hand corner, the other 2 are on the edge of the cartridge connector.
You can now Carefully grasp both sides of the Motherboard, and slide it straight up, over the screw supports and place it on the workbench. (carefull of the RGB Pins)

That's it. to put it all back together, reverse the steps.

But wait, now that its apart, lets take a closer look.True to what was stated on the CoCo 3 page, The Ram is NOT soldered in place, But the ROM, CPU, and just about everything else is . The reason for this is so anyone can upgrade the Ram by removing it, cutting 2 caps, and plugging in an upgrade board for a whopping 512K. Some upgrade boards actually held more. The upgrade board would plug into the 3 white sockets
(Figure 4a)

Click Here to see how to upgrade from the Manual

The only other "socketed" chip is the GIME .

Figure 4a


RAM socketed

CPU - looks "Flater" than its earlier counterparts

The following is the step by step guide that the manual suggest:

DISASSEMBLY.

1. Disconect Power and remove signal cables from unit.
2. Remove the Cartridge from slot (if applicable).
3. Turn unit over and place it on a soft surface to prevent damage to the keyboard or top cover.
4. Loosen and remove the six (four screes S1 and two longer screws S2) mounting screws which attach the base to the top cover. (figure 3-1)
5. Disconnect the cable from the wire connector which is attached to the keyboad (figure 3-2)
6. Disconnect from the power transformer at the 3-pin connector on the main PCB (figure 3-2)
7. Remove four (two screws S3 and 2 screws S4) screws which attach the PCB to the bottom case cover (figure 3-2) If necessary to remove the shield from the PCB, do so by removing the 16 rivits which attach it to the PCB.