New Diodes in Stock TCI

Good day. I've been getting more and more paranoid about my TCI lately. I didn't even know it could be a problem until I started reading threads about it.

After studying these two threads;

http://www.venturerider.org/forum/showthread.php?t=40414

http://www.venturerider.org/forum/showthread.php?t=43357

...and getting some good advice, (Special thanks to Dingy and Timgray), I decided I should look inside the damned box to see what's what.

Before getting into the job, I ran the bike and checked each exhaust pipe with a temperature probe to verify that all four cylinders were firing...and, good news, they were.

To get the TCI apart, there are 4 phillips screws on the back cover, and 5 on the back of the board. Now here's the tricky part about getting the board out of the box; the proper way is to desolder the 14 wires from the board which lead to the connectors.

I'm ok with a soldering iron but no wizard, and that board has been banged around for 25ish years and I don't know how much more abuse it could take. So I decided to try something different. I used a hacksaw and cut the box around the connectors. It was a pretty easy job and it was no problem cutting only the box and not damaging the board.

That bit worked for me. If you choose to do any of this, by the way, you do so at your own risk.

Anyway, the attached pics show what I found on the inside. At least 3 diodes, (the blue and tan bulbous units), were showing signs of serious disintegration. HOLY CRAPPOLA...! That sure gave me a bit of a fright. It made me thankful I tackled this bloody awful bit of mechanicking.

I refused to pull the fairing off so I yanked the battery, battery box, air cleaner and air box. I also took off the lower right side fairing. This allowed me access to the TCI.

I could reach the screws but they were bloody seized. Eventually, I got the left one out. The right one wouldn't budge so I just cut the tab off the box. I wasn't planning on putting the box back in its original spot so I didn't worry about it.

Dingy suggested replacing the crap diodes with 1N4001 or higher diodes, so that was my quest for Sunday. The Source, by Circuit City, (formerly Radio Shack in Canada), had an assortment pack with about 20 diodes and as it turned out 10 of them happened to be of the 1N4001 variety. Less than 6 bucks later, I was off to tackle the bike.

I won't go into what a frickin' pain it was to fart around inside that bike...I will just say that the cuss words are probably still echoing around that garage.

Anyway, I took my time with the desoldering and soldering...(even though it may not look like it). After replacing all 8 diodes, I checked continuity with an ohm meter. One direction would show 600 ohms and the other would show nothing...perfect. I also checked continuity further down the board to make sure my soldering job actually fused to the traces. I had a couple of traces lift while soldering so that took some extra time to resolve.

All of the testing seemed to indicate all was well so it was time to try it on the bike. After plugging the TCI and the rest of the bits back on the bike...SHOWTIME...!

One stab of the starter and she lit right up. Fantastic. I let it run for a while and used a temp probe to verify that all cylinders were firing...which they were.

I haven't taken it on the road yet...it's 4 am and I lost the will to reassemble the rest of the bike and tuck away the TCI.

After much soul searching...the TCI will probably go back in its original spot...but held there with zip ties instead of those damed screws. I plan to silicone up the frankenstein-ish scar I hacked into the box, then, once I'm sure the thing is running right, seal the thing up in a bag with some desiccant.

Anyway, so far, so good. I definitely feel relieved that I went through the effort. The paranoia was getting to me. Now, I feel confident that my potential TCI worries are probably in the past.

One bit of extra advice; desoldering and soldering these bits can screw up your board. The diodes cost me less than 6 bucks. It would take a good electronics tech less than a half hour to do this job...an hour if he's drunk. If you aren't totally confident in your soldering abilities, take the job to a tech. It'll save you from screwing up an otherwise good TCI.

Ok...it's 5am...I'll take the thing out on the road tomorrow, see how it runs and report back.

Joe,

I would encourage you to mount the TCI on top of the air cover while you have it out. You already have the one tab cut off that you need to do to mount it on the airbox anyways. You need to do this in order to get the tank cover to seat properly. Cut tab goes towards battery.

It gets it away from the heat of the cylinder head, as well as in a dry location.

You do not have to cut any wires to do this. Just reroute them.

Looks like you caught the diodes just in time.

That was a good solution to open up the box as well. I had difficulty with lifting traces when I unsoldered the board from the box, what you did looks nice.

Gary

Good posting Joe. I wish I had the nerve to try that. Let us know how it goes.

Ok...I took the bike for a good ride today and everything seems perfectly fine. As far as I can tell, it runs just the same as before. I am pretty confident that whatever I did worked and at the very least didn't cause any harm.

As you can see from the picture, I decided to put the TCI on top of the air cleaner box. It is a tight fit and I may carve down the air box lid a bit to allow for a non interference fit with the fake gas tank cover. I put some dense foam on the TIC to add a bit of cushioning.

So total cost; About 6 bucks. Total time; about a day, (most of which was spent digging the TCI out of the bowels of the bike).

This mod was absolutely worth doing. I thought that maybe the ticking time bomb that is the TCI was a bit of hysteria...until I had a good look at the board. There was nothing to indicate my bike or the TIC had experience any undue hardship...just normal wear and tear.

The contacts on the plugs were showing quite a bit of evidence of corrosion so I cleaned them up a bit and stuffed them full of grease before I reconnected them.

I can only conclude from my experience and the testimony of others that TCI meltdown in more a matter of WHEN, not IF.

If you're happy with your stock bike and aren't looking for much more than you already have out of your ignition circuit AND, (this is an important bit), your stock TIC is still working up to spec, I can totally recommend this mod for some piece of mind.

Any questions? Feel free to ask.

Just be glad it is pre chip era.

Now that you have it apart check those power transistors as well, then the dried up capacitor's should be the next step. my 2 pence..

Indeed...if I keep it up, I'll end up with a whole new TCI in the old box. I reckon I won't be opening the thing up again. I had a good look around and nothing else seems to be on the verge of failure...from what I could tell from my limited experience.

If I was going to do anything else, it would be to take one of these units to China when I go over there and have some local folks do a direct copy of the stock TCI...probably won't though.

The aftermarket TCI's from IgniTech most seem to me to be the best way to go if your unit fails altogether.

In the meantime, I'm just going to ride my bike and not worry about it. I have other chores on the bike I have to take care of...like checking the rear suspension bearings...and the endless series of other things that seem to crop up on a 25 year old bike.

It's more fun to ride than fix so I'll be doing that while it's still summer in the great white north.

Hi,

A member here, DonB if memory serves, looked into this quite extensively a few years ago. He is a retired electrical engineer and did an analysis of TCI internal component parts availability.

The conclusion he came to apparently, was that while most components were readily and generically available in the market place, there were two Yamaha proprietary IC's (large 40 pinners mounted underneath a sub board? memory hazy) which were not available and never would be again.

Hope this is of some help and interest.

Brian H.

PS BTW, I have an ignitech unit on order for my blue bike, who's TCI still works but is rather grumpy much of the time and really hates cold weather.

I have been inside it, replaced all the diodes and reflowed all the solder joints but its still grumpy at best.

I have a spare TCI unit that makes the bike run perfectly when its installed, so I know the problem is in the blue bike's TCI. Relying on that spare though which is 26 years old too seems like a limited time offer, so I committed to ignitech last week.

Indeed...if I keep it up, I'll end up with a whole new TCI in the old box. ...........................

 

If I was going to do anything else, it would be to take one of these units to China when I go over there and have some local folks do a direct copy of the stock TCI.....................

 

I reccomend sealing up the box completely. there are vents in the bottom that are not needed for anything but letting water in. I would also use a LOT of dielectric connector grease on all the connectors after reassembly to further combat water.

Good save on the TCI.. as time goes on we will be having a lot more people with failed TCI's if they dont take care of the diode issue before they fail.

I'm no expert but I suspect that the diode fix only makes sense if the box is still working up to spec. It's probably too late if there has been any damage already.

From having a look around the board when it was open, I couldn't see any other obvious problems, and nothing looked or smelled burnt. Of course, that is no guarantee of anything. As shown by the diodes, old electronics can fail without burning out.

In the long term, an alternative to the stock TCI is the way to go. The Ignitech box looks like a very promising alternative at a pretty reasonable price. I suspect the much more modern guts should prove to be more versatile and reliable and it has a reasonable price.

Kudos to those in here getting the wrinkles ironed out. I know if my box does fail, I will be replacing it instead of attempting to repair it again.

I already sealed up the box completely so there is not much more I can do to it other than run the crap out of it until it fails. My gut feeling is that the unit now has the potential to go on indefinitely.

Regardless it is impossible to keep ahead of all the possible failure points in a 25 year old piece of hardware. I think the repair is worth doing if you have a perfectly running TCI and you have access to an electronics tech. Otherwise, go with the Ignitech unit.

After seeing the degradation of my unit, really doubt there are any TCI's that's aren't on their way to failure at some point in the near future.

Timgray; are you aware of any other likely failure points on the TCI other than the diodes?

Yes the final output transistors, but typically only happen when you either have a bad coil that is shorted and forcing the TCI to try and dump the battery to ground for each spark.

I personally have not see any actual failures outside of ones caused by the Diodes failing. Every failure I have seen has been with the diodes.

The Ingitech is the cheapest way to go. There are other after-market TCI's that will work, problem is they cost a lot... Starting at $680.00 for the ones I was looking at. the only cheaper alternative would be someone finding another yamaha TCI that could work with a little rewiring... Like the Voltage Regulator upgrade we have.

What is the voltage regulator upgrade...?

Joe which ones are the diodes

wow...now my electrically charged brain is working overtime. 1N4001...YOU SAY. I probably have dozens of those. Something for the future... Oh look... I just found a bunch of 1N4004 diodes in my cabinet. These are the same but higher PIV rating.

wow...now my electrically charge brain is working overtime. Something for the future...

Quick get the fire extingisher, or douse the head, in a bucket of ice cold water. I sense that smoke is starting to appear........

I just found a bunch of 1N4004 diodes in my cabinet. These are the same but higher PIV rating. I did note in my "book" 1N4 series is a 1 amp diode. While the stocker looked like the higher rated barrel type ones. Were the numbers readable on the originals...or did you bother too look?

I just found a bunch of 1N4004 diodes in my cabinet. These are the same but higher PIV rating. I did note in my "book" 1N4 series is a 1 amp diode. While the stocker looked like the higher rated barrel type ones. Were the numbers readable on the originals...or did you bother too look?

I bothered to look when I did mine.

There were no identifying numbers. This is not uncommon in massed produced electronics. It is an added expense to imprint components with tagging.

1N4001 is rated at a peak reverse voltage of 50v, 35v RMS

1N4002 is rated at a peak reverse voltage of 100v, 70v RMS

and so on.

The TCI is a 12 volt device.

Any 1N400* series diode can be used in the TCI for the 8 failing diodes. They can be mixed and matched. They will all work.

Worked in my 83 TCI just fine.

Gary

Joe which ones are the diodes

I've attached a picture with a better closeup of the 8 diodes. Four of the Blue/Tan diodes on the right side of the board are labeled. There are 4 others on the left side, arranged in a different pattern, for a total of 8.

Joe how did you know they were bad ? an if your box goes up do you replace all the diodes ?an one last Q, an I'll leave you alone.lol Should you go a head an replace the diodes before the box goes up if its an old one ?

Joe how did you know they were bad ? an if your box goes up do you replace all the diodes ?an one last Q, an I'll leave you alone.lol Should you go a head an replace the diodes before the box goes up if its an old one ?

There has been some speculation on here that once the box goes bad, it stays bad.

When the diodes fail, they take out some other component with them. It may be that there is a time factor to this related failure as well.

It is a preventive type of maintenance.

Gary

The box on Brown Sugar just started dropping tach to zero. Is it too late to fix?

The box on Brown Sugar just started dropping tach to zero. Is it too late to fix?

Is #2 cylinder still firing?

If it is, it will probably still work.

Also, the fuel pump is triggered of off #2, if bike is still in running, I would suspect another problem with tach.

Gary

Joe how did you know they were bad ? an if your box goes up do you replace all the diodes ?an one last Q, an I'll leave you alone.lol Should you go a head an replace the diodes before the box goes up if its an old one ?

I had no idea I had bad diodes other than being told they were a failure item and checking. It was obvious from looking at them that at least 3 were in very bad shape, with at least one other on the way.

I was advised as to what diodes can be inserted and replaced all of the stock ones. So far, my bike has been running perfectly.

As far as I know, there are usually no symptoms to warn when a diode is failing...it just fails and takes some other part of the TCI with it.

Personally, I only advise that one does the diode upgrade if their stock unit is still working perfectly and they, (or whomever they get to do it), has experience soldering electronics...lots of experience.

These boards are old. I had a couple of traces lift while desoldering so they had to be dealt with. I took my time and double checked my work to make sure that everything was working up to spec.

If your board has already failed, I wouldn't bother trying to fix it. It's probably screwed. I would spend the cash and get an IgniTech box. I won't be opening up my box again...if it fails, I'll just toss it.

I had no idea I had bad diodes other than being told they were a failure item and checking. It was obvious from looking at them that at least 3 were in very bad shape, with at least one other on the way.

 

I was advised as to what diodes can be inserted and replaced all of the stock ones. So far, my bike has been running perfectly.

 

As far as I know, there are usually no symptoms to warn when a diode is failing...it just fails and takes some other part of the TCI with it.

 

Personally, I only advise that one does the diode upgrade if there stock unit is still working perfectly and they, (or whomever they get to do it), has experience soldering electronics...lots of experience.

 

These boards are old. I had a couple of traces lift while desoldering so they had to be dealt with. I took my time and double checked my work to make sure that everything was working up to spec.

 

If your board has already failed, I wouldn't bother trying to fix it. It's probably screwed. I would spend the cash and get an IgniTech box. I won't be opening up my box again...if it fails, I'll just toss it.

Does anyone know what the 90-93 box has inside compared to the earlier ones? Can an Igntek box work on 90-93 with its different internals?

Does anyone know what the 90-93 box has inside compared to the earlier ones? Can an Igntek box work on 90-93 with its different internals?

I am almost certain that the Ignitech box will work with the 90-93 bikes.

It will actually be a better fit for these bikes due to the single pick-up coil.

You can download the software at the Ingitech site. They have a fairly long list of bikes that are preprogrammed into the module.

There is already a Venture XVZ 1300 in the list, but it is not for the 83-89 models.

For the 83-89 we are using a Special Setting tab, not a preprogrammed bike.

It may require an few emails to Ignitech, but it can be done.

Gary

I contacted ignitech and they told me that they have a box that works for the 90-93 models, but I have not ordered one yet to know for sure.

Am planning to try one, price is pretty reasonable compared to a new one, less than any used ones that I have been able to find as well.

When I do order the tci, I am going to order a new pickup coil as well. I just have to open the bike up and get a photo and measurements for them so that they send the right on for a Venture. I am getting both at once because the price is quite reasonable on the pickup coil and I am not 100% sure that my ignition problem is not in the coil.