TCI box keeps blowing

Ok after a month of trial and errors and 3 new everythings...stator,pickups,voltage regulators, I have a short some where. I just aqquired a new TCI box for my XJ 650 pluged It in and It made a popping noise and blew It. just by turning on the key. Now that means the other 3 that I have are definatly bad because they were all plugged Into this bike. Is there anyone for the love of god that can tell me why Its doing this. I traced every wire they all look fine Im grounded just like I should be(frame to engine,engine to battery). If I cant find a solution here Im going to take It in for scrap!

 

Replace main Harness?

 

Have you measured the resistances of the primaries on your coils? If one of your coils is short, that will probably blow a TCI pretty quickly... as I doubt that these boxes have the current limiting feature found in modern ignition drivers.

Other than that, the only thing I could think of that would blow a TCI would be if the plugs were actually miswired - specifically if ground and +12V were swapped on the 6-pin plug.

FWIW, there are a couple of guys out there that repair TCI's. If you're handy with a soldering iron and such, and if your TCI's are blowing because of a shorted coil, you can probably repair them by replacing the output transistor that's blown... you may even be able to sub in something like a BIP373 there to add overcurrent protection.

 

Measure the resistance from the 2 pin plug or the acual wire Itself? How would I measure a primary, there is the coil body itself and the 2 plug wires. I belive the 6 pin plug Is comming from the resistor in the headlight as well as the ignition switch. Do you think a faulty switch might cause that? Its ferry frustrating because It was working just fine then all of the sudden whamo no spark and bad TCI units.

 

The resistance of the primaries is measured between the 2-pins of the plugs of the coils. Should be about 2.5 Ohms.

Sorry, misspoke about where the +12V and ground could be swapped... that would be the black and R/W on the 4-pin plug. As far as I can tell from my Haynes manual, the R/W should be next to the Orange on the clip side of the plug, and the Black should be next to the Grey on the flat side of the plug.

Neither plug, though, has anything to do with a resistor anywhere.

The 6-pin plug gets the signals from the pickups, and, depending on the model of bike, may also get the safety cutout for sidestand/clutch/neutral.

 

Screaming, what is your general location? Please consider adding it to your avatar as you never know who could be close by to lend a hand.
That said, I can probably fix your TCI but I don't think the TCI is your problem. You need to sit down and do voltage and resistance checks on your harness, it sounds like you have a short in there somewhere.
Has your harness been monkeyed with? As SQL mentioned, you need to check to ensure that your wiring reflects correct location (pins and connectors) using a schematic to guide you.

 

The only thing thats been messed with on the harness Is the fuse box was replaced. That would be great IF you could fix my TCI. How much would you charge me? I have the wiring diagram and the book but Its not going to tell me which wire is supposed ot have voltage and which one Is a ground. Ill do a resistance check on It tonight and see where Im at.

 

OMG I LOVE YOU ALL!! I had the saftey relay and the tci plug mixed up! SQL your color call out Is axactly what I needed! Robert I took the TCI apart saw a burnt tracer resoldered a jumper wire to fix the tracer and BAM!! It started. I cant thank everyone enough for all the help I am a happy motorcyclist now and Its thanks to everyone here that heard my pleas and lended a hand. If there is anything I can do please let me know right away. I updated my avatar(no pic yet)

 

You are right, the book isn't going to tell you, you need to figure it out. The schematic should show you where the voltage is and where the grounds are. Remember that the battery supplies 12VDC to the system, you just need to figure out where it goes through the system and where it is supposed to return to ground (the frame in our case). There was a member here who made an electricity basics primer for those of us who are electrically challenged, his name escapes me. Do a search and see what you find.
Another useful analogy in chasing this is to think of the voltage as water flowing through pipes. I've had folks tell me about how much easier it is for them to understand electricity when taking this approach.
Your wiring diagram shows wire/pin configuration on the connectors, please verify that your harness matches the schematic.
Disconnect the TCI and look for 12V at the red/white wire on the TCI and ignition coil connectors. Verify the inputs to the TCI are sound (pickup coils are intact)
I will look over your TCI(s) and IF I can fix it (the chip in the TCI isn't something I can fix), I'll charge shipping costs and parts. To date, this has set one of our members back about $15 (your situation may vary depending upon quantity of fried parts).

 

Screaming650, WCH, OHIO????

 

WCH is short for Washington Court House Ohio. Im about 45 min south of columbus.

 

Awesome! Glad to hear it's worked out and that the advice was helpful. Sounds like you have a few extra, hopefully repairable, TCI boxes on your hands now.

Cheers,
Paul

 

Yeah my excitement didnt last long. I was a dummy and didnt check all the plugs for fire my TCI is still bad Its only sparking one of the coils. I think It will still need repaired. I tried to find a schematic on the board Inside but no luck.

 

anyone In Ohio have an extra one? I would gladly come get It and pay good money for It.

 

looking at the 4-pin plug ON the ignitor, where should the r/w and orange plugs be? I know on the clip side, but which is left and which is right? same with the gray and black..?

 

im hoping im not having this problem and just dont know it yet...

I built a custom, bare bones harness for my 82 650 maxim, basically everything works, headlight, tail/brake light, ignition switch, starter button/starter, yet i have no spark at the plugs... the bike cranks and cranks, just no spark...

I checked voltage at at the coil and tci wires and im getting about 11.5v at both r/w's and the orange, but only 1.25v at the gray, and this with the igntion on, but not pulsing the starter.

Any ideas???
my coils are defintely grounded well, the metal blocks on both ends of both coils are bolted directly to bare metal. i have new plugs. coils and plug wires dont appear damaged, all solder connections are solid and shrink wrapped.

Could i have wires plugged in wrong at the TCI?