# burning out hall effect sensors



## Tom Jamboretz (May 28, 2010)

I have 4 model single cylinder engines using the hall effect and Tim-6 ignition system. One of the engines has burned out 8 sensors in the last 2 years. No problem with the others. 
  I talked to Jerry Howell before he passed away and he gave a few suggestions but they did not help. He suggested braiding the wires from the sensor and another ground connection near the sensor. I would sure like to know if others have had similar problems and how they solved it.   TJ


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## bearcar1 (May 28, 2010)

I'd be curious to know what it is that is different about the model you are experiencing the difficulties with as opposed to the other models in your stable. Usually failures to HE devices are the direct result of overvoltage or reverse polarity conditions. Static charges could also be a suspect but without anything to go by that is unlikely. Pictures? or any other kind of descriptive outline of this particular ignition setup would help us in determining why you are having such a high failure rate.

BC1
Jim


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## gbritnell (May 29, 2010)

Tom, I have had 2 types of failures when using HE sensors. One is when it's used in a distributor type ignition (multi cylinder) and the other is when I have a poor ground situation. The HE sensors on my 302 and V-twin work great but the distributor I made for my small inline 4 doesn't. The reason is the overall size of the 4 distributor is smaller and I get an occasional errant spark which burns up the sensor. 
 The other time I've burned up a sensor is when my ground wire comes loose. By that I mean the Hall sensor has 3 wires, positive, negative and signal. You still need a good ground wire to the engine to return or ground the spark. 
 Like Jim said, there's got to be something different between your setups that's causing this to happen. 
gbritnell


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## Kermit (May 29, 2010)

a solenoid(coil) needs a bypass diode to suppress reverse voltage spikes. 

A Hall Effect sensor is sensitive to reverse polarity (kills them).


I'm thinking...something wrong with the ignition kit(they do have a suppression diode don't they?)

or perhaps a cold solder joint that only rarely opens far enough to cause the problem.

easist fix might just be to add a reverse protection diode external to the kit. On the HE sensor even.

Kermit


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## Tom Jamboretz (May 29, 2010)

Here are a few photos of the set-up.  TJ


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## bearcar1 (May 29, 2010)

Hi Tom, I really hate to be a PIA but how does this setup compare to the others on engines that you have not experienced problems with. Also, can you tell us what that alligator clip shown in the lower left hand corner of that shot is for?

BC1
Jim


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## Kermit (May 29, 2010)

What is that? and what is it made of and why is it there??(see attached)

Everything else looks acceptable for carrying electrons around...


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## Tom Jamboretz (May 29, 2010)

The alligator clips are for ground from the coil. One is connected to a cooling pipe while the other is connected to the brass conduit carring the sensor wires to the sensor. The gold colored material is sting holding sensor in placed then covered with a glue.

 On the other engines the sensor is held to a arm of metal or plastic with string and glue. On those engine the sensor and bar can be moved to change ignition timing. 

  Thanks for the interest.  TJ


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## bearcar1 (May 29, 2010)

That is informative Tom, do you ground your other engines in the same manner using alligator clips? 

BC1
Jim


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## Tom Jamboretz (May 30, 2010)

The answer to that is yes. TJ


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## bearcar1 (May 30, 2010)

Well, so much for that theory I had. Does that alligator clip have anything to do with the hall effect circuit at all other than providing a return path for the plug? I cannot see any electrical connections to the sensor itself. My theory was that the alligator clip was not providing a good enough connection or was perhaps being vibrated enough to cause an intermittent connection while the engine was running. hmmmm.....

BC1
Jim


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## Kermit (May 31, 2010)

Alright. I'll pursue my guess. A question for you then TJ, and a belated Welcome to HMEM from me!

You said this string was 'gold' colored, suggesting a metal based addition to the material.
Are the other strings(on other ignition systems) also of the same gold material, or did you use different string to hold the other sensors in place?

Kermit


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## Lakc (Jun 2, 2010)

Kermit  said:
			
		

> a solenoid(coil) needs a bypass diode to suppress reverse voltage spikes.
> 
> A Hall Effect sensor is sensitive to reverse polarity (kills them).
> 
> ...



I concur wholeheartedly. ;D A complete ignition system should have diodes for reverse voltage and zener diodes for overvoltage protection. It would be interesting to see a complete schematic of the TIM systems to see what level of protection is included, but it certainly cant hurt adding more. There are also single chip opto-isolator systems that can be used as well.


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## Tom Jamboretz (Jun 4, 2010)

Sorry for the slow reply -- been out of town. As to the gold string. It is 45lb. braided polyester fishing line. The package does not say anything about any metal being in it. I have it on my Economy model and it has been running about 4 years. 

  As to the reverse polarity question. The latter Tim-6's have a reverse protection diode. 

                       TJ


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## Lakc (Jun 5, 2010)

Tom Jamboretz  said:
			
		

> Sorry for the slow reply -- been out of town. As to the gold string. It is 45lb. braided polyester fishing line. The package does not say anything about any metal being in it. I have it on my Economy model and it has been running about 4 years.
> 
> As to the reverse polarity question. The latter Tim-6's have a reverse protection diode.
> 
> TJ



Throw that string in the microwave for a few seconds and see if it gets warm, that will tell you if it has metal in it or not. Try and think of a way to replace the alligator clip with a good ground strap.

The diode in the tim6 just appears to be there in case the power and grounds are reversed, the schematic I saw did not have any real supression techniques involved at all. A few capacitors across the hall sensor power supply and the ignition unit would be a tremendous improvement, and a liberal sprinkling of zener diodes would be the professional way to handle it. 

The high voltage that comes out of the coil can do seemingly strange things at times, but it will always try and find the shortest path to ground. Occasionally, that path could be straight through the ignition unit, or the coil itself, and the carbon tracks it will leave behind will just make it that much more likely to happen again. Also watch out for the wiring rubbing on the end of the copper tubing, as sharp as it can be, it really should have a bellmouth at the exits.


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## Blogwitch (Jun 5, 2010)

Tom,

Having used these things and had no trouble with them, all I can suggest is one thing.

Somewhere in the back of my mind, I remember reading about when the engine is stopped, the magnet and trigger should be well apart, because as soon as you turn the system on, it can blow the hall if it is in a position where it is activated by the magnet.

When engines stop, sometimes they have a favourite resting position, and maybe yours stops with the magnet and sensor in that critical position.

Maybe you need to reposition the two critical items so that scenario doesn't occur, or always make sure they are well apart before turning on.

Hope this helps


Bogs


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## Tom Jamboretz (Jun 28, 2010)

Thanks to everyone who had suggestions and ideas to solve my problem. I checked out all of the suggestions and made the changes and never did find the problem. I've put another new sensor on the engine. We will see what happens.    Tom


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