1985 Stock ignitor GS550 repair help

[victorgallas]

Hi there.
I had mentioned in the past that I was able to revive my ignitor unit in the past after it got burned out from me using a wrong ignition coil that pulled more current than the factory ones do. After upgrading the ignition coils to a set of black dyna's and then using an oscilloscope to probe the circuit inside the igniter unit, I was able to determine that the output transistors that amplify the signal to the coils had been damaged. After carefully taking the circuit out of its case and breaking the old epoxy used, I was able to solder in a new set of transistors.
Currently I am using a set of Radio shack TIP3055 NPN Transistor part number 276-2020. The problem that i currently have is that this transistor gets too hot during normal use, and I am afraid it would burn out much quicker and leave me stranded on the side of the road.
Can anyone provide an input as to what would a good replacement for this application could be?
Here is the spec sheet on the current transistor I am using.

http://www.datasheetcatalog.org/datasheet/stmicroelectronics/4136.pdf

I think that I need a transistor that has more power capacity than the current one I am using.

Any inputs are very welcome.

Thanks
Victor

[tom203]

If this transistor is basically just a switch that "grounds" out the ignition coil when triggered by gate signal, why not try to substitute a n-channel mosfet with low on resistance to do the switching?

(member obsidianghost in CA was/is working on this ignitor also)

[Steve]

The problem that i currently have is that this transistor gets too hot during normal use, ...

What do you consider to be "too hot"?

What temperature is it hitting?

The spec sheet says it will handle 15 amps, you are well within that, as long as your coils are at least 2 ohms each. I did not bother to look up the specs on the "black coils", so I don't know what you are running.

Besides the 15 amp rating, the spec sheet says max operating temperature is 150 C, which is 302 F. It may be warm, but it's probably within its limits. Mount it to a heat sink, direct some air across it, go for a ride.

.

[duaneage]

I repaired an ignitor for a GSR member a few years go with that Radio Shack transistor and it worked .

[victorgallas]

Thanks for the replies.

I think you are all correct that the 15 amp should be plenty for the applycation.
Currently its using the stock heatsink that just pushes against the back of the transistor in the case. I am going to try on getting a better heatsink and take it for a spin.
I will obviously do a write up of what I did once I finalize this. I am moving to TN by next friday, so all the bike stuff has been put in boxes for the move. Ill get back to the project soon thou! I want to enjoy summer too

Thanks everyone

[tom203]

Victorgallas, did you see this post?? moving can be distracting

http://www.thegsresources.com/_forum/showthread.php?t=195295