What cause stock Ignition box (TCI box) transitor to burn out!

[nghieplk]

Hi everyone, newbie here.

Mine is 1980 heritage special.
I've replace the stock regulator by new 3 phrase regulator, and do modify the stock stator. My bike running a stock tci box.

Last few days ago, i've spent my holiday time on a 4 days tour. On my country, the road is so bad that i cannot ride fast. But on the last day, i suddenly increase the speed of the bike to the top speed. Then my bike suddenly shutdown and cannot start (by both kick or electric start). And while checking the problem, i see that some transitors in the tci box has burned! (attached image)

Why this happened? Maybe because of the regulator or the stator....I'll take a picture when i back home. My friend told me I need to turn on the headlight while riding?

And i wonder if does it necessary to get a new, reliable charging/iginition system to replace the old stock one, for the compatibility and synchronization. Because its the 2nd time my tci box has problem.

Thank you and appreciate all the help!

 

[littlebill31]

Could be from vibration.
That box is 37 yrs old. Your ignition and charging are two seperate systems, so I dont think its related.

Edit: Make sure you check the red/ white wire that runs to the fuse box. Hardwiring without a fuse can fry them.

 

[Paul Sutton]

Could just be an old dying transistor. The replacement for this big transistor is a ST901T. This is very easy to get hold off and is designed for ignition systems.

http://www.ebay.vn/san-pham/1pcs-st901t--encapsulation-to220--371174358902.html

Also check the 4 ceramic diodes are still good.

 

[gggGary]

Get a volt meter on it watch that it isn't charging over 14 volts. Yes a headlight and large stock battery both work to reduce the chance of voltage spikes hurting electronics.

 

[weekendrider]

Some of the cause may be cracked solder connections creating, resistance and heat. It has been awhile but 7 - 10 years ago several reported saving the TCI by simply reheating/melting the solder connections that had cracked over time. One poster was able to locate the bad connections by using a plastic probe to move the joints.

 

[mrtwowheel]

I found bad solder joints in a TCI box once by running the bike in the dark and seeing the sparks at the bad solder joints. Maybe some bad solder joints caused the heat?

Also, these bad joints are usually a darker gray than the good joints.

Scott

 

[jetmechmarty]

Gary says check the charging voltage. Good idea. Are you running the stock coil? If you recently replaced it with the wrong one, it will cause a problem in the TCI box.

 

[nghieplk]

Thank you guys!
Here is the bike coil. I think its the stock one?

 

[littlebill31]

I see a lot of mud and such.
Does your TCI get wet?

 

[jetmechmarty]

It may or may not be stock. The factory never mounted a coil with zip ties to my knowledge. It could have come from another bike.

 

[nghieplk]

Yes my bike has been rebuilt (repaint, restore healthy engine...) by a mechanic/custom guy in my area, so he did move and re-position some electric parts.
And there's a lot of rain on those days i ride, but the tci box isn't got wet, because it is in a sealed-up box , just the coil is wet i think, because my bike doesnt have a front fender, lol. And when it rain, i noticed the ignition doesn't work correct (1 spark ignition weaker than another, and sometime only the left side of the engine work). Does it because of the wet coil?

I just calm to wait my bike return home, then i'll take some picture, or ask the mechanic guy to check and fix it. At the moment, it's lunar new year holiday here and nobody ship the bike back home, it's about 1000km far away my home now (i'm from Vietnam)

Btw, here is the picture of my bike. I'm really happy with it. But in my country so hard to find a guy own an xs650 like me in order to study or discuss about it.

 

[Paul Sutton]

Very nice looking bike you have! The drum brake on the front is really cool with the tread pattern you chose.

 

[littlebill31]

I like the DT tank. Nice bike!

 

[weekendrider]

Nice bike.

 

[nghieplk]

hi guys,
i just came back after some hard-working days.
Question, I see there're really nice CDI system from hughshandbuilt. And really want to get one to replace my fucking old TCI box that burn out as I mentioned above.
http://www.hughshandbuilt.com/product/complete-xs650-cdi-system/

Is this system will work in my case? Any good or downside of it?

 

[retiredgentleman]

I would avoid the hughshandbuilt system. Its very expensive and low quality. Also its not good to have the charging system and the ignition in one package......................if the alternator burns up it destroys the ignition as well.

Pamcopete offers a well proven ignition system that is not expensive and is high quality. You will be able to use your existing ignition coil. I'm not clear on what charging system you are using, but if its working just keep on using it. Its best to keep the ignition system and charging system separate. Pamcopete offers a system specifically for the 1980 to 1983 years, and his site has the installation instructions:
http://www.yamahaxs650.com/

 

[nghieplk]

There're many package of pamco i found on mikes site:
https://www.mikesxs.net/electrical/pamco-ignitions-and-parts.html

Which one will fit better my case? I think i should replace the ignition coil also.

And i see the setup for later 1980 xs650 is a bit complicated as ive never tried it before (install the additional advance, the rod...) in order to make it work. Are there any complete install guide and parts for 1980 tci xs like me?

 

[littlebill31]

This si the one you want. It comes with a coil.
https://www.mikesxs.net/yamaha-xs65...igh-output-ignition-system-advance-73-84.html

It's not hard to install. I think there are some videos on Youtube.
It's a great ignition system.
Some people want to spend the $500 on another system, not sure why. The Pamco is great. As long as your charging system is good, this system will work for you, no problems. And with your rough roads, simpler is better.

 

[nghieplk]

Thank you!
How about charging system? Any suggest? I just want to make a fresh new install cause dont want it fail again on long touring days...

 

[littlebill31]

Has your charging system failed before?
Most times a little maintenance goes a long way. Clean it, new brushes, ect. A whole lot cheaper and reliable than most aftermarket ones.
My charging system is 37 yrs old and still works perfectly.