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TCI box - a successful repair, electronic ignition, ignitor

Discussion in 'The Garage' started by xjwmx, Sep 6, 2010.

  1. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    TCI box - a successful repair

    My '81 xs650 had been sputtering or more often just shutting itself off for no apparent reason - annoying in the middle of a sharp turn or pulling out into traffic. After checking various blind alleys I happened to notice that when I flipped the kill switch to "run" the neutral light would sometimes dim, which seemed strange. A glance at the circuit diagram shows the switch runs from +12 to the ignitor box. I hooked up my spare ignitor box and saw that the neutral light stayed bright. I left it hooked up and that fixed the problem with the bike.


    I didn't see any obvious problems inside the ignitor box, but I recognized four white egg-shaped diodes, D1-D4, as being similar to one that had failed shorted inside a relay causing my neutral light to come on when the clutch lever switch was activated. I believe those diodes are fragile. In the ignitor box I scraped off some clear conformal coating from the diode pads and tested the diodes and discovered a couple had low resistance in both directions. They're easy to test in-circuit since they just run out to the cable.

    I replaced the four diodes with 1N4005 diodes from Radio Shack. Since putting this box back on the bike it hasn't shown any problems. Before the fix the bike would have shut itself off a dozen times in this amount of time. If you make this repair, the marked end of the diodes should face to the left, and make sure they are solidly against the board when you solder them in, for strength against vibration. A dab of flexible glue under them wouldn't hurt.

    ~~~~~~~~~~~~~~~~~~~~~~
    UPDATE 11 Dec 2010

    A few days after writing the above, I had another, similar, stalling episode. At that point I removed the box again and examined all the solder joints on the board carefully. I saw several bad ones, a kind of degradation I hadn't seen before, caused by vibration I presume. See the third picture. The picture is an extreme case; look for just a faint ring as well.

    Soooo, I used acetone and a toothbrush to remove the coating from the solder side of the board. I let it dry for awhile near a heat source. I then proceeded to re-solder every single joint on the board, adding a little solder to each joint. The purpose was to fix bad joints as well any joint on its way to becoming bad. I then used a toothbrush and denatured alcohol to remove the melted rosin solder flux left behind. I reinstalled the box, and as of now, 3 mos of daily riding later, haven't had a failure of any kind with it. The solder side of the board is still uncoated. I may put a coating on it if I stumble across one I like.
     

    Attached Files:

    Last edited: Dec 11, 2010
  2. blue900

    blue900 XS650 Addict

    Thanks for posting that. Nice repair.
    I have an 81.
    I have found many times, It sure is a lot cheaper to fix the parts you have than to replace.

    One of my goals is to learn some electronics hacking.

    Its cooling down but I'm gonna ride it to work in the morning anyway.
     
  3. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    The diodes were 0.99 per bag of 2. There's a family of diodes 1N4001-5 and probably higher, that are all similar and would probably all work. The 5 had the highest rating that was the same price and size. The circuit has two in series to increase the voltage they can block, and with the new ones it'll block 1000V :)

    Nothing like a cool morning ride in Idaho! Second best is pondering it while at work. Enjoy.
     
  4. anysnail

    anysnail XS650 Addict

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    i think i totally toasted my tci box though i have yet to get it off the frame. i know absolutely nothing about circuit boards and soldering so i'm thinking of just going with a point system.

    same topic different gear: did your bike just shut off at random times while you were driving it? cuz that's what mine did and i thought it was the coil going out. turns out it wasn't the coil but i did fry the new one i put in.
     
  5. anysnail

    anysnail XS650 Addict

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    oops computer goofed and i posted my comment twice.
     
  6. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    Yep that's what it was doing. The dynamics of your motor shutting off in the middle of a turn is truly amazing.

    I got the spare TCI box I used for testing on ebay for about $30. Someone actually auctioned one rather than trying to sell it outright for $90. Meaning they can be had at a decent price.
     
  7. anysnail

    anysnail XS650 Addict

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    lol! i like the way you phrased that. i guess you could call it amazing i was more intensely frustrated by it. oh well. i'll gonna just take that archaic microchip out and do the more reliable mechanical system.
     
  8. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    Ever since I've had this bike I've considered going to points ignition because the old-timeyness of it appeals to me. Plus you have diagrams, and you don't have a schematic for the box. I haven't looked into whether the stuff is available to do it.
     
  9. anysnail

    anysnail XS650 Addict

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    oh it's definitely available. pamco pete sells it as a kit on mixesxs. but i was thinking if you are such a pro, and you are, at fixing TCIs maybe you could take a look at mine? eh? eeehhhhh? :D
     
  10. kvanderploeg

    kvanderploeg The Dutch Terror

    xjwmx - Thank you!!! Just bought my '80 and the PO had put in a TCI from an '81 that looked worse than the original '80 box. Luckily he still had it and sent it along in the bag of goodies. The bike would start and run, but above about 1/3 - 1/2 throttle it would cut out. Replaced 4 diodes with Radio Shack's:

    1N4004 Micro 1-Amp Rectifier Diode
    Catalog #: 276-1103

    They didn't have the one you listed, but this should work fine as each is rated for a PIV of 400V. As you said, they are in series, so 800V total. After swapping them out, the bike runs and revs like a champ! Saved me some money in the short term. Might still go Pamco, but at least it's running right now. Again, Thank You!!!

    Kent

    The completed repair:

    [​IMG]

    The 4 black diodes in the upper right corner:

    [​IMG]

    The original diodes:

    [​IMG]
     
    Last edited: Sep 9, 2010
  11. anysnail

    anysnail XS650 Addict

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    you guys got me thinking that i might be able to fix my TCI without having to put in the pamco points system. is it really just that easy?
     
  12. kvanderploeg

    kvanderploeg The Dutch Terror

    I've done a fair amount of soldering in my day, but only a little at the component level. Having a good little soldering iron, a solder bulb/sucker, and a little pan vise to hold the board, and I was done in about 15 minutes. Took me longer to dig through the drawer at Radio Shack to find the parts. Radio Shack ain't what it used to be. I'm not saying it will be the "fix" for everyone, but for $2 for 4 diodes and a little time, why not?

    Kent
     
  13. pumps

    pumps XS650 Junkie

    xsjohn-rest his soul, used to be a great believer that the stock tci box was the best ignition for these bikes. Good advance curve I think he said and crank triggered is good.:thumbsup:You guys out to sell your repair services!
     
  14. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    Anysnail, you can fix it yourself if it's fixable. The cheapest iron at R.S. is probably best for you. Read a page on soldering and get some de-solder braid at R.S. to soak up some of the left-behind solder before you put the new parts on.

    If replacing the diodes doesn't fix it, then replace the transistor too. The MJE5742 is available from digikey.com for a couple bucks and about $5 shipping. The TIP120 doesn't leave much margin current-wise I think. But it has more gain. Take the original transistor out carefully in case it's not bad and the replacement really isn't a good one.

    kvanderploeg, that's not like my boards. Yours has a lot more components. Might be from a different model bike? Glad it works though.


    P.S. Anysnail - before you replace anything, examine the board and look for any component that looks burned or popped. If you find one, that might be all you need to replace.
     
    Last edited: Sep 9, 2010
  15. kvanderploeg

    kvanderploeg The Dutch Terror

  16. xjwmx

    xjwmx It's just the unknown. Top Contributor

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    I have two, both supposedly '81 that are the same and don't look like either of yours. Yours has nice fiberglass double-sided boards and mine is single sided brown stuff.
     
  17. kvanderploeg

    kvanderploeg The Dutch Terror

    The one that I fixed was supposedly the original for my '80, and the one I just posted has written in marker on the side "XS650 '80", so who knows. Perhaps they had a few factories making these, as my repaired box says "Hitachi Ltd. Tokyo, Japan" on it. Either way, I'm happy it works!

    Kent
     
  18. Love it, you guys rock!
    And kudos on the thread heading, should be easy to find in the future searches!
     
    Last edited: Sep 9, 2010
  19. anysnail

    anysnail XS650 Addict

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    does anyone know if i can use this stock TCI box with a pamco green monster ignition coil? i am looking at buying a used ignition system from one of the other members on this site and i really don't know much about ignition systems. i guess what i'm trying to ask is should i go with the pamco points igniton system or buy the used TCI and put the new coil on?
     
  20. chickenone

    chickenone XS650 New Member

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    kVander
    your second pic of Tci looks just like mine from a 81 xs400.. only my grey wire is providing spark... is power supposed to come out of Grey and orange wire?? 11.80 is coming out of grey and 3.70 comes out of orange..volts that is :).. thanks i need help..wiring from ground up..
     

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