Sport 1100i and Similar Computer Repair

    Youíre out for a drive one morning on your beautiful Yellow 1100 Sporti. While sitting at a stoplight, miles from home or any other type of civilization, the engine dies. You re-start it. It dies again but this time there are no warning lights and no power to the starter. You check the fuses: all OK. You check the relays. No problem there. Soon the battery seems to regain life. The instrument lights come back on. The headlight is bright, but thereís not enough power in the battery to run the starter.

     What do you do? A) Push start the bike? B) Have a passerby jump-start your battery with jumper cables? C) Walk 60 miles, uphill, in the snow, to the nearest phone to make a deal with the devil to bring you a fully charged battery?

     Well unlike me, you should pick C.

     Now for those of us still living in the old days of non-computerized motorcycles and picked A or B, hereís whatís going to happen, unless youíre very lucky. You will push or jump-start your motorcycle and drive it about 300 yards as it spits and sputters until it finally dies with no electrical power. No problem, youíll just have a friend lend you a battery to get home on. When you hook it up and turn on the key, the bike wonít fire. You stop and listen. The fuel pump is still running and from past experience this means the computer is not getting power. Sure enough the fuse is blown.  Put a new one in and it blows. This is where you will finally pick option C. You get the bike home and start to trouble shoot the problem. You will eventually pull out the access plug on the top of the computer and smell inside. No question, you have burned something up. A few phone calls later and you find out a new computer will cost you $750.  Now what do you do?

     Well luckily for you I have already figured that part out and will share my knowledge. Iím not going into all of the electrical reasons why this happen because I donít know what they are for sure and it really doesnít matter as long as you never pick options A or B again.

     Cut away as much of the silicone sealant that holds the top of the computer on as possible. Then, carefully pry off the top, starting at either end of the connector plug. Remove the 8 Torx screws (4 long and 4 short) that hold the circuit board in the computer box, and carefully pry it out.

     Look at the printed circuit board, holding it with the plug pointed towards you. In the lower left area you will see a large capacitor. This 220uf capacitor is a cylinder shape about 3/8 inch in diameter. Just to the left of it is a black power regulator. It Ūs about 3/8 inch and has one visible lead coming off it soldiered to the circuit board. This is the item that needs to be replaced. It should smell burned and show signs of a brown burned area around it. Carefully pry the regulator up from the circuit board. It will remove the circuit board conductor it is mounted to. Do not remove any more of conductor on the circuit board than what is just under the regulator. Remove the regulator by cutting the main lead attaching it to the circuit board. 

     Go to an electronic supply shop and purchase a 30-volt maximum input to 5-volt output voltage regulator with a 2-amp current rating. It will be larger than the one you removed and will have three leads coming from it, ground, voltage in (>30 volts) and voltage out (5 volts). Be sure to get a spec sheet or something to tell you what the leads are. Place the new regulator on the right side heat sink board and drill a hole for the mounting screw.

     Trim and bend the leads on the regulator and mount it to the heat sink leaving the thin insulation barrier intact. Use a 2-inch small-gauge solid-core wire, like used on telephones, to go from pin #16 though the middle hole of the three that are located between the old regulator and its connection on the circuit board, and carefully soldier it on the back of the board.. (pre-solder all connection and wires first) Connect the >30V input lead to pin #35 (top most right), 5V output to pin #34 (one left of 35) and the ground, with a ring connector, screwed to the circuit board ground. Use a 2-inch small-gauge solid-core wire, like used on telephones, to go from pin #34 though the middle hole of the three that are located between the old regulator and its connection on the circuit board, and carefully soldier it on the back of the board.

 
See a picture of this here.

     Now for a quick check to see if you have fixed it: Plug the circuit board into the bikeís connector and run a ground lead for the circuit board to the battery ground. Replace the bad battery and the blown fuse and turn on the ignition. The fuel pump should run for a few seconds and then stop. Turn the ignition off and wait about 10 seconds and you should hear the computer power relay click off. Screw the circuit board back into the computer box and use silicone to reseal the computer. Re-install the computer and all wiring. Turn on the ignition and hit the start button.

     If it starts, take yourself out for a lobster dinner and leave the other $700 in the bank!


Bill Doll
dollwe@bv.com