TCI troubles

[jdabreeze]

Been taking time fixing some roadside/redneck electrical repairs on my 1980 special. Yesterday I replaced the starter solenoid and put the ballast resistor back in the ignition circuit. Would only run when cranking, so I check voltage at ballast 2vt jumping to 9 during crankin, check voltage at TCI output to ballast 2vt. Remove TCI and clean contacts for wiring harness and decide lets open this up and see what we can see.



lets take a close look



that don't look good, the second one is burned through or broke when I checked to see if it was.

Is there a schematic of the circuit board to determine what this circuit went to?.. I will assume it is for the ballast resistor. I have read that bypassing the ballast will cook the coils but it has been 2 years? and 3-5000 miles since that road side repair with no issues at this point in time. I may just throw back on and see if it runs at all now. Any other suggestions while I try and find my soldering iron.

[James England]

You can repair that PCB with your soldering iron. Is that what you meant?

[jdabreeze]

You can repair that PCB with your soldering iron. Is that what you meant?

Thats what I was going to try to do,but would like to know what specifically that trace did and not assume it was for the ballast. That is why I asked about a schematic of the board. I hopefully can fix the damage but would like to know how it got damaged and prevent it in the future.
Also the question about the ballast and coils. If I can't get 12v out of TCI(even after its repaired) to the ballast and take it out of the ignition circuit again, what problems am I looking at down the road, remember that the ballast has been out of the loop for 3-5000 miles already.

[James England]

So, just to check.... you've been running the bike with 1.5 ohm coils and no ballast resistor? And it ran fine for thousands of miles? Then you decided to put the ballast resistor back... (why was that?) And, at that point, the bike will only run when the starter button is pushed, correct? If that's the case, your ballast resistor is defective.

PCB's are easy enough to repair. Just use some circuit wire across the 'blobs'...

[natemoen]

The ballast resistor is there to reduce the current through the TCI not the coils. Your damage there is most likely because the TCI got cooked because you were running without the ballast resistor.

If you are lucky the burnt traces are all that fried. DO NOT run for any more than a few minutes at most without the ballast resistor.

[James England]

The ballast resistor is there to reduce the current through the TCI not the coils. Your damage there is most likely because the TCI got cooked because you were running without the ballast resistor.

If you are lucky the burnt traces are all that fried. DO NOT run for any more than a few minutes at most without the ballast resistor.

That's incorrect Nathan. When fitting 3 ohm Dynacoils instead of the OEM 1.5, you remove the ballast resistor and join the two wires together. That's it. You leave the TCI exactly as is and it doesn't fry at all. In fact, it's in no danger of doing so. The ballast resistor dissipates 1.5 ohms once the starter button is released (it cranks on a full 3 ohms), enabling the coils to run at 1.5 ohms.

When fitting the green 3 ohm Dynas, you get full current through the coils all the time, hence getting a healthier, fatter spark than the OEM setup. 1.5 ohm coils don't like this (although jdabreeze's lasted a long time despite this) and often burn out...hence fitting 3 ohm coils when the ballast resistor is removed. I ran mine for at least 2 years with green Dynas, no BR and same TCI. that's the usual, normal way to do this mod.

[natemoen]

You are thinking backwards here James. The XS and XJ ignition system all use a 3 ohm system. Whether you have 1.5 ohm coils or 3 ohm coils. With the 1.5 ohm coils you MUST have the 1.5 ohm ballast resistor in place create the total of 3 ohm resistance in the system. You can put pretty much any coil you want in there as long as your total ohm rating is 3 or more with all the combined components.

The ballast resistor is only bypassed during cracking because the coils and TCI cannot handle the 1.5 ohms for very long without frying but it gives a bit more current for that brief moment. One of them is going to fry with less than 3 ohms, which one no one knows. In this case the TCI won (or lost I guess that is).

[cywelchjr]

As Nate said, running 1.5 ohm coils without the ballast resistor will damage either the coils or the TCI, whichever is the weaker of the two. If you have 3 ohm coils then you run without a ballast resistor as the system is already seeing the 3 ohms it needs without it, and as a matter of fact will not run correctly with the ballast resistor in that case. The 81 and newer bikes came from the factory (at least in the U.S.) with 3 ohm coils already and no ballast resistor. So in this case the fact of running without the ballast resistor and with 1.5 ohm coils and having the damaged traces points to damage from the lack of the ballast resistor. Hopefully it's not because one of the driver transistors burned out, that would complicate things a good bit more, or require a replacement TCI.

[jdabreeze]

TCI repaired and ballast reads 1.5 looks like a short somewhere. To set the record straight I did not "remove" ballast from circuit, my poor choice of words. A broken "I" wire(cranking v) at the solenoid left me unable to restart the bike. I ran a switched hot wire to where the "I" wire went into the wiring harness, thus providing continuous voltage not just cranking voltage. Its been like that since with no problems. I replaced the solenoid because of other reasons and put the wiring it back to normal. I may just put the hot wire back on and keep going.

[cywelchjr]

TCI repaired and ballast reads 1.5 looks like a short somewhere. To set the record straight I did not "remove" ballast from circuit, my poor choice of words. A broken "I" wire(cranking v) at the solenoid left me unable to restart the bike. I ran a switched hot wire to where the "I" wire went into the wiring harness, thus providing continuous voltage not just cranking voltage. Its been like that since with no problems. I replaced the solenoid because of other reasons and put the wiring it back to normal. I may just put the hot wire back on and keep going.

If you've run a wire putting voltage into the line the solenoid makes hot during cranking all the time that's the same as bypassing the ballast and is likely the cause of the TCI damage and if you keep it that way will just end up with the same problem again. You need to find out what the REAL problem is with why it's not working and not do a bandaid fix that in practice removes the ballast resistor from the circuit, that will just cause damage. It sounds to me like you might have a problem with your kill switch, that can cause issues rather like you seem to be describing.

[James England]

You are thinking backwards here James. The XS and XJ ignition system all use a 3 ohm system. Whether you have 1.5 ohm coils or 3 ohm coils. With the 1.5 ohm coils you MUST have the 1.5 ohm ballast resistor in place create the total of 3 ohm resistance in the system. You can put pretty much any coil you want in there as long as your total ohm rating is 3 or more with all the combined components.

The ballast resistor is only bypassed during cracking because the coils and TCI cannot handle the 1.5 ohms for very long without frying but it gives a bit more current for that brief moment. One of them is going to fry with less than 3 ohms, which one no one knows. In this case the TCI won (or lost I guess that is).

Got you! I see what you mean. In the case of my green Dynas, they already had the 3 ohms, so the ballast resistor could be safely removed.... right?

[cywelchjr]

Got you! I see what you mean. In the case of my green Dynas, they already had the 3 ohms, so the ballast resistor could be safely removed.... right?

Not only could, but for good operation needed to be. But the TCI does indeed need to see 3 ohms, whether it gets that from a set of 3 ohm coils or from 1.5 ohm coils + 1.5 ohm ballast resistor, either one works fine.

[WMarshy]

Good discussion!

I was scoping out a set of Accel coils (#140404) on ebay who said they were removed from a running XS11. Come to find out, the 140404's are the 0.7 ohm coils. I had a hard time at first trying to figure out the specs of these but was glad to figure it out before buying them. Now this thread comes up and I get to learn what (likely happen to the bike they came off) it would have done to my bike. Its likely the coils were being used with the resistor and the TCI was seeing 2.2 ohm and not the 3.0 required... If the bike was running like the seller said, I think it was on borrowed time.

My post...
http://www.xs11.com/forum/showthread...597#post378597