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TCI rebuild thread.

Discussion in 'XJ DIY How-To Instructions' started by darkfibre, Jun 23, 2012.

  1. darkfibre

    darkfibre Member

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    Following on from this thread: http://www.xjbikes.com/Forums/viewtopic ... rt=15.html
    tumbleweed_biff has sent me his dead TCI to (hopefully) repair.



    So we have this:
    [​IMG]



    The already diagnosed blown driver transistor:
    [​IMG]

    Underside:
    [​IMG]



    Time to remove the ceramic thick film board and the electrolytic capacitors:
    [​IMG]


    The main part of the board is fine:
    [​IMG]


    Not so good for the board under the heatsinks:
    [​IMG]

    So that's it for tonight, tomorrow will be time to clean up the board with acetone and re-solder the existing components in the undamaged area.

    The damaged are will need a lot of work, as once the board has been burnt it will conduct instead of insulate causing future failures. Options to consider are isolating that section, or carving out the board.

    I may repair the undamaged section first, and make the transistors a separate board/heatsink. That would be the quickest way to test that the circuitry is functional before committing too much time.

    Common faults on these TCI units are normally fractured solder joints and aged/leaking electrolytic capacitors. This sort of failure will probably have an external cause (currently unknown).
     
  2. bigfitz52

    bigfitz52 Well-Known Member

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    Masochist.

    Good job though, keep it up. This should be in "FAQ Suggestions."
     
  3. trickedout420

    trickedout420 Member

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    how much do you charge to do something like this? i cant find anyone here in the states close to me who wants to even attempt this
     
  4. mtnbikecrazy55

    mtnbikecrazy55 Active Member

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    awesome. also wondering about what someone would charge for this. im sure that if you wanted to, you could have quite a few people coming to you wanting work like such.

    keep it up and keep up with the updates!
     
  5. darkfibre

    darkfibre Member

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    I am not charging for this, for a few simple reasons.
    I offered my services.
    This repair (if sucsessful) would not be viable for an hourly rate anyway.

    Once you charge and accept jobs, you are obliged to produce the goods rapidly and honor a warranty on something that is 30 years old.

    That means I can (since my last post in this thread) get out for a ride to a pub and eat lamb (on the spit) rolls while listening to a bush band!
    as well as a few social events.


    I will not be looking for any jobs until I have my Pumba project past stage 3.
     
  6. tumbleweed_biff

    tumbleweed_biff Active Member

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    When Darkfibre had looked at this he told me it was not economically viable to repair but that as a project to write up and such it was worthwhile to him with no guarantee of success but a good probability in his estimation.

    I just recalled seeing something about such in the past and a search found that at one time, Robert offered a service to do this but I don't know if he still does. Also, I doubt he would resurrect something this far gone. If he no longer does, perhaps he is willing to publish his learnings from the various TCI's he has worked on? For a long time he was accepting the donation of dead TCI's for learning and repair ... I suggest a PM to him might be a good way to go. He said at the time ('09) that he hadn't figured out how to get into the epoxy'ed box of the xj700, ... my answer was a dremel type tool with a cutting wheel to remove and then I will have to make a custom box - the old one was a total loss ...

    I also recall someone mentioning a business which did such, but I can't find a reference to such. As I recall, it referred to dealing with cold solder joints, etc., as opposed to a catastrophic event such as mine experienced (which I suspect was a result of the PO using automotive coils and allowing them to hang loose and short against the engine block - or maybe any of a dozen plus hacks of the wiring harness).

    For those of you with the funds, I suggest trying Chacal to see if he has any for your bike in his stock. For me, financially, Darkfibre's offer to try as a project was a God-send. I hope his efforts and write-ups will be a blessing for members of the forum for years to come. In my case, my electrical/circuit skills are about a 0.5 out of 10, logic 9 of 10, soldering 2 of 10, steady hands 2 of 10, so such a project is far beyond the scope of my ability even with such a write up.
     
  7. trickedout420

    trickedout420 Member

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    well either way i would love to see how this project turns out.
     
  8. darkfibre

    darkfibre Member

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    Board is now cleaned up (ignoring the burnt areas) and resoldered. Most of the caps have been replaced, I just have to get some 0.47uF caps that I thought I had on hand :(

    Should be able to then bench test it without the output transistors to see if the unit is functional very soon. Then its time to work out the neatest way to mount the transistors.
     
  9. Ground-Hugger

    Ground-Hugger Member

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    How about a parts list with part/component numbers when you are done? Great post and take/post lots of step by step pics!
     
  10. darkfibre

    darkfibre Member

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    Bench test without transistors was successful.

    Bench test with the modern VB921z ignition driver transistors also successful.

    Of to buy some connectors to make an adapter harness to test it on Pumba (750 Seca).

    Results and more pics later.
     
  11. darkfibre

    darkfibre Member

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    OK.

    New capacitors and a resolder, powered up with no smoke!

    [​IMG]


    And we have an output pulse to drive the transistors :D


    [​IMG]

    So its time to cut away the tracks around the burnt area.

    [​IMG]

    One of the good things about the VB291 ignition driver is the fact the case is insulated, unlike the original transistor. Some odd modifications due to the lack of surface tracks:

    [​IMG]

    Tracks jumped over with tinned copper wire and silicone tubing.

    [​IMG]

    And done (yes, it's messy :( )

    [​IMG]
     
  12. tumbleweed_biff

    tumbleweed_biff Active Member

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    WOW!
    Messy? Who cares?! I don't see how it could have been neater given the damage. The fact is, you resurrected it and upgraded the transistors at the same time. Something far beyond my abilities.
     
  13. darkfibre

    darkfibre Member

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  14. MN-Maxims

    MN-Maxims St. Paul Minnesota

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    For something that looks as bad as that did when you started I never thought it would work. Good job

    MN
     
  15. darkfibre

    darkfibre Member

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    Now that is is working, I just have to support the components that I have floating in the air or over time the vibration from the bike will cause fractures at the solder connections. I just have to get my hot melt glue gun back from a mate.

    Tumbleweed_biff, do you have the cover still as the one I am using on it at the moment is not a spare.

    NOTE: Do NOT swap TCI units between a 700X and a 750 Seca as the wiring connections are different - I made an adapter to do this.

    For test purposes I made a harness adapter, and found the XJ700X TCI to perform close to standard over about 2,000rpm but very soggy under that.

    Adapter:

    [​IMG]
     
  16. mirco

    mirco Member

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    Wow! Nice job man!
     
  17. tumbleweed_biff

    tumbleweed_biff Active Member

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    Darkfibre,
    The box was a write-off. Not only was part of it melted from the heat event, but the thing was glued to the board all the way around and I had to cut the box apart with a Dremel to get to the board. I expected I was going to have to make one out of something. It will probably look like $@#% as I am not good with precision stuff. I was hoping to find a project box about the right size I could adapt ...
     
  18. daveheller

    daveheller New Member

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    Wow this is awesome.. I am in aw of your know how..
     
  19. jmilliken

    jmilliken Well-Known Member

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    I believe I may have mentioned this on another thread, but would it be possible or feasible to build a "new" TCI?
     
  20. iwingameover

    iwingameover Active Member

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    All things are possible.

    The main hurdles I see are sourcing the main chips and the program and equipment to burn the program onto them. If you had that you'd probably be able to do it.
     

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