Hello again folks!
Today I want to cover a very common fault with the Colecovision - their power switches. Basically, they are very mechanical in nature, and easily get dirty and cease to work. Often this means you'll get a picture on your TV, but it may be totally scrambled, or just black, or whatever. Most people would never suspect the power switch but it's easily the most common Colecovision repair job you'll see.
First things first, if you just want to repair your switch, it's pretty simple too. Just follow along, you'll see what to do.
What you'll need:
1) A new switch. I'm using Radio Shack part number 275-691 ($3.99), because it happened to be available for cheap on eBay when I looked for one.
And you thought Radio Shack wasn't relevant anymore.
The Colecovision uses 3 power rails to work, +5V, +12V and -5V. -5V is always on the board, it's not switched, it's just used for the specific type of DRAM Coleco decided to use. There is an upgrade available to use nice new DRAM that doesn't require -5V, but it's quite a bit of work.
So to be able to simultaneously switch on 2 power rails at once, you'll need a Double Pole switch, either Single Throw or Double Throw:
Looks sort of like variation 10352 and 10353 on a Coleco Telstar pong unit.
These switches are labeled as DPST and DPDT, respectively. The Double Throw feature isn't used in our case, since we are just making/breaking the connection on both. The biggest concern here is whether the switch will fit in the hole and be able to be securely attached. I got lucky with this one, it fits perfectly once you remove a bit of plastic with pliers and attaches with a screw (panel mount).
2) Wires, solder, desolder braid or vacuum tool.
1) Disassemble your Colecovision. This means:
- Remove the screws from the bottom of your Colecovision. There are 8 or so of them, but there are not any hidden ones under stickers.
- Separate the two halves. The top half comes straight up off the bottom half, but there is a bit of resistance, so be careful. Don't force anything and make sure you've removed the all the screws.
- Remove the few screws around the RF shield, and desolder the corner that's held down.
- Remove a few more screws holding down the board.
- Take off the lower shielding for now.
2) Remove old switch. Here, use your trusty desolder braid or vacuum (braid works better, trust me) to remove the old switch. First desolder the two clips holding down the top half of the switch and remove it. You'll see this:
Cheap mechanical switches were in fashion in the early 80s with Atari, Mattel and Coleco.
Here's where our repair-only journey ends. Clean these contacts with either actual contact cleaner or some suitable lubricant like WD-40 (not tested by me!), reassemble and your switch is good as new. I'll see you again in 5 years.
For those who are upgrading, continue by removing the rest of the switch. Fill those empty holes with solder, and prepare 4 lengths of wire about 6-10 inches long. 4 different colors are preferred to help you avoid blowing your Colecovision up. If you have the materials, prepare 8 wires and a connector in the middle so you'll be able to disconnect the halves of your Colecovision in the future.
Now, solder in your 4 wires. The column of 3 holes towards the edge of the board is +5V, and the column of 3 holes towards the middle of the board is +12V. If you flip the board over, you'll see that two pairs of holes are already connected, so if you solder both pairs of wires into those holes, your switch will not work. Either use my method like below by choosing the four holes furthest away from the expansion connector, or by not connecting the middle holes. Again, if you mess this up on the board side, it just won't power up.
The four wires I used are from a cocktail arcade game that was 'accidentally' scrapped for parts by myself. Oops.
2) Physically Install your new switch on the top half of your Colecovision. Your method may vary since I don't know what type of switch you bought. For my switch, I had to remove some plastic with my dremel so the screw would reach the thread.
These shots were used in Star Wars as part of the Death Star trench chase.
3) Connect your four wires to the switch. It is very important that you preserve the columns of wires. If you mix up the wires to your switch, you'll provide +12V to the chips that only can handle +5V, and you'll probably fry them.
If you have a DPST switch, your wiring should be clear. Referring to the image above, your goal is to provide continuity between the red and green wires above, and continuity between the brown and blue wires, when the switch activated.
If you have a DPDT switch, wire one wire from each column to the middle pins of your switch, then wire the other ones to either the top or bottom of their corresponding side. Again, make sure you are preserving the columns so you don't cross the +5V and +12V.
Red and green on one side, blue and brown on the other, just like the columns on the board.
4) Reassemble and test! If you get smoke, you messed up, sorry. If you used a DPDT and your Colecovision turns on when it's in the "off" position and vice versa, crack it open again and move your non-middle-pin wires to the other side. If you get nothing at all, make sure you used the correct 4 holes on the board. Again, the outside four (so not using the middle hole of each column) works fine.
5) You're done! Good work team.
The Colecovision pictured here is for sale in the For Sale / Trade section of the site. It's also A/V modded for optimal picture/sound!