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TCI repair

Started by auto, August 05, 2019, 07:51:15 AM

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auto

Helping my son sell my old vision and keep his new one running.Just went through a rash of TCI failures.Has anyone had success diagnosing and repairing a bad TCI unit. Or point us to someone who repair/upgrade these units.

jefferson

There really isn't that many cases of tci failure that I know about. Since you are having several I would make sure you have the wiring correct. The plug from the stator will plug into the tci and fry it. The plug from the ignition and stator are the same so I would check that first. You didn't mention if it takes some time for this to happen or what.

auto

I think I killed one that way. The one that went bad on my sons bike ,just failed.It had been running fine for some time. Bad design on Yamaha part to allow connector to cross fit.If anyone has one to sell I'm interested.Yes I know there on ebay.

fret not

There is a reliable source in the Czech Republic, Ignitech,  They make ignition and fuel control modules for various applications and can supply one for the XZ550.   

http://www.ignitech.cz/english/aindex.htm
Retired, on the downhill slide. . . . . . . . still feels like going uphill!

The Prophet of Doom


I have a graveyard of about a dozen TCI's I've gleaned from parts bikes and parts sales (plus my own bikes).  Failure is more common than you would think, and not all from plugging the wrong wires I'm sure.  Mostly they just stop sparking in one lead, but I've had one that sparked both plugs but wouldn't advance.  It idled fine but produced no power at higher revs.

Near the bottom of the Resources post is Leather's musings about the TCI workings and repair - Give that a read.


+1 for the Ignitech - they are great units much loved by the Germans and available in regular "Sparker" or programmable "TCIP4" model.  The programmable can give you 3D ignition curve if you fit a TPS or MAP sensor, and can be re-used on just about any bike by re-flashing it.


There are also much cheaper TCIs available on aliexpress.com for the XZ550 - can't vouch for these though.

fret not

The main problem I found with trying to repair a TCI unit was getting it apart cleanly and without damaging anything.  It requires unsoldering a bar connector from the PC board so the board can be removed from the case.  Then, after replacing any bad item on the PC board it all has to go back cleanly into the case and be resoldered.  All the little parts have numbers on them but you need a really good magnifying glass.  (take a pic with a digital camera, then enlarge it - had to do this to read numbers on some jets)
Retired, on the downhill slide. . . . . . . . still feels like going uphill!

auto

I actually found and repaired the issue.Same condition and location on three TCI units. Break in the circuit board copper band.looks to be heat and age.opened up the back on two of them and transistors and diodes seem to test good.The two zener diodes will test bad untill you remove them.Question I have is there seems to be two types of boxes.One with a label the other with out.The one with a label has a jumper wire on the board and row less of resistors.Any idea which is early or late production? any difference in performance? Have most of you cut the yellow rev limiter wire to the TCI box?

Walt_M.

Have you looked at the Dave's electrical FAQ tab in the Technical section,  it's at the top of the page, in the blue. He did a great write up on the TCI, well worth the read.
Whale oil beef hooked!

ArrrGeee

#8
Quote from: auto on August 07, 2019, 11:52:18 AM
I actually found and repaired the issue.Same condition and location on three TCI units. Break in the circuit board copper band.looks to be heat and age.opened up the back on two of them and transistors and diodes seem to test good.The two zener diodes will test bad untill you remove them.Question I have is there seems to be two types of boxes.One with a label the other with out.The one with a label has a jumper wire on the board and row less of resistors.Any idea which is early or late production? any difference in performance? Have most of you cut the yellow rev limiter wire to the TCI box?

auto, that is great news, I spent some time trying to repair one of these, replace a bunch of parts but never got
the rear cylinder sparking again, I eventually replaced it with an ignitech unit.
however, I and probably a few of the other guys would be interested in what you found, maybe some pictures if you can swing it.

thanks!

-Ron


to answer your question, yes on cutting the rev limiter, it's one of the first things the guys do when
the bike has running problems.




injuhneer

I agree. Some photos of the repair or the defect/failure would be great.
- Mike O
1982 Yamaha XZ550RJ

The Prophet of Doom

#10

It's been raining and cold lately, so started looking at my TCI which has no spark on one channel.
Once the lid is off A $5 solder sucker makes pretty short work of the 10 edge connectors. Undo the screw and the board lifts straight out. 
A quick inspection shows a number of problems:
Solder side:

       
  • A broken trace on the P1 connector
  • Soldering is very poor - porous and dull with big voids
Component side:

       
  • A couple of the electrolytic capacitors are showing signs of bloating - though no leakage yet
  • The conformal coating has broken down and very slightly conductive
  • Diodes showing signs of overheating
  • More big poor quality solder blobs

fret not

That is a nice view of the PC board, both pics are interesting.  It took a while for the pic to load so I could see it.
Retired, on the downhill slide. . . . . . . . still feels like going uphill!

The Prophet of Doom


Thanks Fret,
Here's the full solder side.  All cleaned up and all re-soldered.  Hitachi use a fairly high temp solder which is sluggish and pretty nasty to remove.  I found the best way was to add some additional solder (flux core) before sucking it all up, and then replacing.  I've decided to replace all the caps as a precautionary measure - they are well past their use by date, and less than $1 each.  Christmas is not the time to be ordering - may take a while before they arrive.

fiat-doctor

Sounds like a good plan.  Late 80's and early 90's Honda Accords have a computer for the auto trans that has a similar problem... bulging, leaking caps..   It's so common that there are kits on ebay with the required parts.  I have done a couple and they both worked :)

Also on Honda, the main relay for the fuel injection and fuel pump fails often and most times it is just a cracked solder joint to the circuit board and those cracks are almost invisible...  I just re-flow the solder and it seems to work fine.   Best of luck

MikeScoot

Quote from: fiat-doctor on December 21, 2019, 09:41:35 AM

Also on Honda, the main relay for the fuel injection and fuel pump fails often and most times it is just a cracked solder joint to the circuit board and those cracks are almost invisible...  I just re-flow the solder and it seems to work fine.   Best of luck

I know I'm going to be a bit off-topic here, but it's a funny story.
I had a Civic which wouldn't restart after being parked when hot. After checking everything under the sun I came across a post by some mechanic working out of a home garage in England who reckoned there were two possible fixes. The first was to re-solder all the ignition module components and if that didn't work then the second was to put on a sturdy pair of boots, move the front passenger seat back to be able to get a good swing, and then boot the daylights out of the ignition unit.
Tried the first fix to no avail, so I put my steel-cappers on and gave the unit a really good kick - took a couple of goes to get my aim just right.
That second fix worked a treat and the unit gave no more trouble after that.

Often wondered whether that second method would work as well on noisy neighbors.

Oh, and just for the record; I accidentally hooked my TCI up to the stator too, but after realizing my error I replugged it the right way and still got good spark on both leads. Yet to find out whether it still works when the plugs are back in place in the heads.
Both Luthers had their dreams,
But I've just got one Vision.
Theirs got them into strifes,
Mine just takes me fishin'.