Repairing an Intellivision Ribbon Power Cable

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Why I Had To Learn To Do This

Skip this crap and gimme the info!

The controllers on my old INTV System III were behaving poorly after my unit saw heavy action in the dorms in my sophomore year of college. This was back in the last days of INTV Corp's existence, back in 1987-88. In about 1990, I decided to attempt to repair the controllers by purchasing some conductive coating - some expensive stuff sort of like paint, but that is a good conductor of electricity. The stuff sure looked like the material used on the circuit traces in the mylars inside the controllers...

Well, finally in about 1995 I got around to trying the repair, having moved many more times, including out of the country, and then across it. After "repairing" some of the broken traces, one controller failed to work at all. I figured some sloppy tracing on my part had shorted a couple of the conductive traces on the mylars. Eventually, I ended up opening the unit and removing the controllers from the main logic board, to test which circuits closed when certain buttons were pressed, et. al. What I mapped out turned out to be the same as what can be found in the Intellivision FAQ - I just based my pin assignments on what was at the socket connector at the end of the cable rather than the contacts inside the controller itself.

My efforts were fruitless. I found no problems when testing the controllers via an Ohmmeter. In a rush for some reason, I partially reassembled the INTV System III and threw it back into the closet. I had an Intellivision II to fall back on, which was OK as long as I didn't feel ike playing those awesome Coleco games.

Five years later, I dragged the beast back out. That's when I inadvertently learned that it's possible to repair the INTV System III (and other models) with the wires from a 6-conductor telephone cable, or CAT 3 or CAT 5 Ethernet cable! (That is, if you can't easily get some FlexiCable and appropriate support parts.)

How is that, you ask? Well, I was cleaning up my INTV System III master component and attempting to finish my controller repair project. If you've ever disassembled a 3504 (or 2609) to detach the controllers, you'll notice that the main logic board is connected to a small power circuit board (the one with the big capacitors on it) with a small, 5-conductor ribbon-type cable. The cable doesn't have a decent connector on it - not much better than five bare wires that insert into a 5-pin socket.

In my haste to test the controllers - having forgotten the way they're supposed to connect - I was repeatedly removing and reattaching them with different orientations of socket relative to the pins. When shifting the logic board to connect the right-hand controller, the ribbon cable broke away from the solder points on the main logic board in several places.

Well, that little ribbon cable is just BARELY long enough as it is, so there wasn't enough of it left to re-solder it onto the main board. That, coupled with a ridiculously oversized soldering gun, led to the mutilation of the original cable.

Hmm, what to use for a replacement? Having added my own extra Ethernet and telephone lines when our house was under construction, the idea popped into my head that the conductors in those cables seemed about the right size. The conductors proved sufficient - in fact probably higher gage than the originals - and they fit nicely into the socket on the power supply circuit.

It looked ugly when disassembled, but who cares? Worked fine! Well, it turns out my little repair wasn't quite the end of the problem. Whilst firing up Safecracker, my old INTV III went out on me again. I thought for sure it was just that the cart needed cleaning. But no, nothing worked. Upon further investigation, I found that several problems had arisen.

One of the small wires had broken loose from the main board - again. Also, it seemed that as the unit heated up, problems got worse. Well, it turns out one of the printed circuit traces on the small power board had broken loose around the solder-through hole. So, I wired a bypass for that, and re-wired the system using an old DE-9 male / female pair to make the thing more easily detachable. While at it, I inserted some insulated blade connectors to the LED, since those wires had been pulled out and reinserted numerous times. Once again, the unit seems fine.

Ultimately, the original problem with the unresponsive controller proved to be mechanical. The slot I called "socket 1", which is the "main" pin with which all controller actions eventually close a circuit, wasn't making proper contact with pin 1 on the main logic board. Thus, no controller signals ever reached the main unit. This proved maddening in that when testing the controllers by hand with an Ohmmeter, they seemed to work fine. The solution was to carefully pull out the small spring-loaded contact for socket 1, bend it out a bit, and reinsert it into the plastic case. Works like a champ!

So, electrically the unit has remained sound - the only problems have been mechanical and age-related.

Usually, the symptom indicating the problem is one of the following:

  • Blank picture
  • No video signal at all

To determine if this is actually the problem, you'll have to open up the unit.

To repair the ribbon cable connector, you'll need the following items:

Tools & Supplies

  • Soldering iron with a small, narrow tip, and larger, flatter tip (a $10 15W Wal-Mart special will suffice)
  • Desoldering braid
  • Solder suitable for electronics
  • Philips screwdriver
  • Needle-nose pliers
  • Wire cutters, or a small cutting tool like a razor blade or Exacto knife
  • Possibly 1/4" Hex Nut driver (some Master Components used hex-head screws internally)
  • Multimeter (capable of measuring up to 20 V DC and continuity)
  • Heat-shrink tubing or electrical tape (Radio Shack has this)


  • Wire (22 gage solid or stranded) (telephone cable, or CAT3 or better Ethernet cable work well)
  • Male D-sub 9 connector with solder cups (optional)
  • Female D-sub 9 connector with solder cups (optional)

DISCLAIMER: Do this at your own risk! It worked for me. I'm assuming you've got some familiarity with the guts of an Intellivision, and can handle a soldering iron and the tools involved here.

This repair is illustrated for "standard" Intellivision units (i.e. any version except for the Intellivision II). There is no reason why it shouldn't work just as well on an Intellivision II.

  1. Open the Intellivision Console and Logic Assembly
    Follow this link for step-by-step instructions.

    Intellivision Internals (ribbon cable highlighted)

  2. Inspect the Ribbon Cable
    Use your multimeter to check the continuity of the ribbon cable from the end strands back to the logic board, and even further into the board. Check the board-side connections on the side opposite the one where the chips are visible.

    Ribbon Cable

  3. Repair the Cable
    If you realize that one or more connections are weak or broken, there are several approaches to solving the problem. If the connector leads themselves seem healthy, but the cable is separating from them, use some 22-gage wire to solder a new set of conductors between the connectors, as illustrated below. You can leave the existing cable there. Cut the wires to be slightly shorter than the ribbon cable itself. Note that you can do this repair without removing the original cable from the main board.

    Repaired Ribbon Cable

    If you've determined that repairing the cable is your best option, then jump to step 7 after soldering the new wires onto the old connectors. Leave the ribbon cable intact.

  4. Replace the Cable
    If you've determined that the existing ribbon cable is a lost cause, you can choose to replace the cable instead. The approach documented here isn't the prettiest, and is certainly less than optimal, but it works. You might try splitting a 10 conductor ribbon cable in half and slicing up the connectors, too. I haven't located the necessary parts for such a venture. Or, if you find a 5-conductor ribbon cable and connectors, use that. I believe VCRs may contain similar parts, so if you have a broken one that you can gut for parts, check it out! The approach described here documents using CAT3 Ethernet cable and a pair of D-sub 9 connectors...

    Example of a D-sub 9 connector: D-sub 9 Connector (end view)

    1. Desolder and remove the original ribbon cable.
    2. Cut two 2-3 inch pieces of CAT3 cable. Let's call them "A" and "B".
    3. Remove enough of the outer casing to expose 5 of the conductors on each end, and strip them. Leave the outer casing on the rest of the cable.
    4. Cut the remaining 3 wires down so they won't interfere. Do not just pull them out - otherwise the remaining wires will just slip out of the casing!
    5. Solder the five wires from cable "A" to the top row of 5 solder cups on the male D-sub 9 connector. Repeat this with cable "B" on the female D-sub 9 connector.
      D-sub 9 M-F Connection Ribbon Cable Replacement (left) D-sub 9 M-F Connection Ribbon Cable Replacement (right)
      Check continuity for each of the conductors.
    6. Remove the power conditioning circuit. To do this, you will need to remove two Phillips screws and disconnect the connector that leads to the transformer.
    7. Desolder the 5-pin female connector for the ribbon cable, removing it from the power conditioning circuit's printed circuit board. Be careful to avoid damaging the circuit traces!
    8. Solder the other ends of the 5 wires of cable "A" to the 5 holes where the ribbon cable connector used to be. Be sure that you insert the wires from the top side (the side with all the parts on it) through the holes, soldering them on the bottom side.

      Replacement Ribbon Cable Connections
    9. Solder cable "B" to the main logic board in a manner similar to that used in step 8.
    10. Connect the male and female D-sub 9s together and check continuity.
    11. Reinstall the power conditioning circuit.

  5. Check Continuity
    Connect the ribbon cable or its replacement back to power conditioning board and the main logic board. Use a multimeter to verify valid connections from the power conditioning unit all the way back to the main logic board. Also, make sure that no two pins in the connector cable short together. You will get a finite resistance between them (a few k-Ohms), but you should never get a 0-Ohm reading. If so, locate the cause of the short and repair it.

  6. Test the Intellivision
    Verify that the Intellivision works by trying to play a game. If it doesn't, double-check the connections and the voltages. If it still doesn't work, it's possible there are other problems with the system.

  7. Reassemble Logic Board Assembly
    Disconnect the logic board again if necessary and put the metal casing back onto the logic board, and solder back shut. (Not necessary on Intellivision II.)

  8. Reassemble your Intellivision
    Assuming the system works, reassemble and enjoy!

All of the parts listed here - the wire and D-sub 9 connectors - are available at a TinkerTronics, Digi-Key, or Radio Shack type of store.