Alternative to TIP3055 NPN Transistor for Early Suzuki CDI Ignition Module?

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#1 21662643 19 Jun 2012 06:12

Nick Jagodinski Nick Jagodinski

Anonymous

Post #1
21662643 19 Jun 2012 06:12

Some friends and I from a Suzuki motorcycle forum are having some trouble locating a transistor. It belongs to a cdi ignition module on our early 's motorcycles. After some trial and error we determined that the transistors were bad. We have found a replacement (radio shack #276-2020 tip3055 npn type) but it seems it gets too hot under normal use. Can anybody help us figure out an alternative component so we dont get stranded on the side of the road? Any help is greatly appreciated.
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#2 21662644 19 Jun 2012 08:54

David Adams David Adams

Anonymous

Post #2
21662644 19 Jun 2012 08:54

What was the original part number on the transistor? You have replaced it with a power transistor with hi wattage. It should have a heat sink - if it is still too hot with the heat sink on it chances are you have another problem. what cause the other transistor to go bad ?? Bad coil maybe? Or should I say going bad - like it may have some shorted turns which would cause the current to rise and cause the transistor to get hotter.
#3 21662645 19 Jun 2012 09:55

DAVID CUTHBERT DAVID CUTHBERT

Anonymous

Post #3
21662645 19 Jun 2012 09:55

How hot is too hot? The transistor junction can run 125 deg C and be reliable. As a quick but effective test see if you can keep your finger on it during operation. If so this indicates the transistor case is 70 deg C or below. This would be fine. If it sizzles a wet finger it is too hot.
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#4 21662646 19 Jun 2012 10:03

Frank Bushnell Frank Bushnell

Anonymous

Post #4
21662646 19 Jun 2012 10:03

It is normal for some transistors in some circuits to get very hot, due to the current passing through them.
Therefore larger (high power) transistors are commonly mounted on a heat sink to prevent them getting too hot.
The TIP3055 datasheet says it is rated at 90 Watts so yes, even if that is sufficiently similar to the original transistor, it may well get hot !
Is there someome on your forum who has one of these ignition systems (without a fault) who can tell you if the original part normally gets hot ?

So if the original transistor was bolted to a lump of metal, make sure your replacement is bolted down to it before you turn the ignition on.

Can you post a circuit diagram and maybe a picture so that we have some more information to figure out what the problem might be ?
And as David says, what is the marking on the original transistor, and could it be that another component in the circuit has caused the transistor to become faulty ?
#5 21662647 19 Jun 2012 11:25

Nick Jagodinski Nick Jagodinski

Anonymous

Post #5
21662647 19 Jun 2012 11:25

Not sure of the original part number. It does have a heat sink but compared to a good unit, it is much hotter. Bad coils are probably what killed the original ones, but they have been replaced with new ones of similar resistance.
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#6 21662648 19 Jun 2012 13:25

David Adams David Adams

Anonymous

Post #6
21662648 19 Jun 2012 13:25

MEASURE THE CURRENT OF A GOOD UNIT AND THEN COMPARE TO THE CURRENT YOUR UNIT DRAWS. I AM OF THE MIND SET THAT YOU HAVE AN ADDITIONAL PROBLEM, CAUSING YOUR UNIT TO RUN HOT - LIKE MAYBE A GROUND
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#7 21662649 19 Jun 2012 14:13

Sarah Harris Sarah Harris

Anonymous

Post #7
21662649 19 Jun 2012 14:13

what model suzuki ? if it is a true CDI, and they are the switching of the "CD" part of the circuit , they are switching in excess of 300v.
this is usually on old 2 strokes. if its a 4 stroke, then its a different story. also check you have the coil polarity correct,
#8 21662650 19 Jun 2012 22:46

Steve Lawson Steve Lawson

Anonymous

Post #8
21662650 19 Jun 2012 22:46

As well a bolting the transistor down, did you use thermal paste (also called thermal grease, thermal compound, or thermal gel)? That can make a huge difference, as the paste provides a conductive path for the heat from the transistor case to the heat sink.
#9 21662651 20 Jun 2012 04:01

Nick Jagodinski Nick Jagodinski

Anonymous

Post #9
21662651 20 Jun 2012 04:01

Its a 1983 gs550e. 4 cycle, 4 cylinder.
#10 21662652 20 Jun 2012 14:59

DAVID CUTHBERT DAVID CUTHBERT

Anonymous

Post #10
21662652 20 Jun 2012 14:59

The CDI circuits I've seen use a high voltage transistor to drive the ignition transformer primary.

Is the transistor in question used to switch the transformer primary or is it the inverter transistor to generate the high voltage?
#11 21662653 19 Sep 2012 03:13

cyrilgrace Feria cyrilgrace Feria

Anonymous

Post #11
21662653 19 Sep 2012 03:13

*transistor * **is a simeconductor device use to amplyfy and switch electronic signals and electronic power
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Topic summary

A Suzuki motorcycle forum user seeks an alternative to the TIP3055 NPN transistor used in the CDI ignition module of an early 1983 GS550E 4-cylinder, 4-stroke Suzuki. The TIP3055 replacement transistor runs excessively hot despite using a heat sink, raising concerns about reliability and potential roadside failure. Responses highlight the importance of verifying the original transistor part number, ensuring proper heat sinking with thermal paste, and checking for underlying issues such as faulty ignition coils or incorrect coil polarity that may cause excessive current and overheating. The TIP3055 is a high-power transistor rated at 90W and can normally run hot, but if it is hotter than a known good unit, additional circuit faults or grounding issues may be present. Measuring current draw and comparing it to a good unit is recommended. Clarification is sought on whether the transistor switches the ignition transformer primary or functions as an inverter transistor. Overall, the discussion emphasizes troubleshooting the entire ignition circuit and proper thermal management rather than simply substituting the transistor.
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Alternative to TIP3055 NPN Transistor for Early Suzuki CDI Ignition Module?

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Topic summary