Tecumseh hs 40 Lighted Coil condensers role?

#2
The condenser in all points type ignition systems' function is to minimize arcing across the points. It does this by dampening the rate of build up of voltage from the magneto. Think of it like an electrical shock absorber to save your points from getting scorched.
 
#3
The condenser in all points type ignition systems' function is to minimize arcing across the points. It does this by dampening the rate of build up of voltage from the magneto. Think of it like an electrical shock absorber to save your points from getting scorched.
Is there a way to test this component?
Reaper
 
#5
Yes with an ohm meter. Set to ohms like you're measuring resistance, red lead to the wire, black lead to the case. You should see on the meter a value that changes. (You should not be reading infinity) Change meter to DC, and again apply the leads to the condenser. You should see whatever voltage you applied when you were charging it with your ohm meter. About a half volt. This value should slowly drop.
 
#6
You've just blasted what I've always believed what was the condensers role in the ignition.
I always thought the condensers role was to store the electrical charge until the points open.
At this point the charge was released to the spark plug.
Reaper
 
#7
From that fountain of knowledge, Wikipedia:

"The capacitor suppresses arcing at the points when they open; without the capacitor, the energy stored in the coil would be expended at an arc across the points rather than at the spark plug gap."
 
#8
You've just blasted what I've always believed what was the condensers role in the ignition. I always thought the condensers role was to store the electrical charge until the points open. At this point the charge was released to the spark plug. Reaper
Don't feel alone. It's not an aspect of the ignition system widely discussed, and it's taken for granted and almost in the history books, now that we have solid state devices like reluctors, pulse generating sensors firing external coils.

Since you asked specifically about Tecumseh, (all points systems operate under the same theory) there is an explanation similar to mine in the Tecumseh manual: The condenser acts as an electrical shock absorber to prevent arcing between the contact points as they open.

When the points are closed, the low tension side of the magneto is shorted to ground through the condenser. Nothing is happening. Once the points begin to open, that side of the magneto no longer sees a short to ground, (zero voltage potential) but an uncharged capacitor. This allows the now quickly building voltage to charge the capacitor (condenser) instead of arcing across the opening points. By the time the points open, the condenser is charged, and the infinite open across the open points allows the stored energy in the high tension side of the magneto to fire up the plug wire.

The engine will fire with a missing condenser, or a condenser that is failed "open." However, a condenser can short, and in that case, the engine will not fire. It's like your kill switch being on.
 

cfh

Well-Known Member
#9
Correct the condenser is a spark suppressor. without it, the points would pit and eventually eat themselves and fail.

After a coil is charged, once the power is turned off to the coil, you get a "back lash" of basically twice the voltage as the coil de-energizes. this causes a big blue spark across the points, which will eventually eats the face of the tungsten points. if this happens long enough, the points won't "make" any more, and engine won't run. The condensor (basically it's a capacitor) absorbs this to minimize the spark across the points. Note it does not completely remove the spark though. That's why points wear out and need to be replaced (or at least re-faced).

Capacitors (even in a metal case!) don't last forever. When i install a new condenser I always write the date of the install with a sharpie on the condenser's case. personally i wouldn't expect a condenser to last more than 5 years. but in a mini bike that gets limited use, it could go longer. they are a consumable, and they are cheap. if there's any question, just replace it.
 
#10
Today I connected an Ohm Meter to the condenser.
Just to check for continuity and no response at all.
Although I did the skin test and there's current flowing.
Just no spark on any plug I connect, I used new plugs, old plugs from Tec four HP.
I can't figure out why this coil won't fire?
Reaper
 
#11
Condenser will charge from ohmmeter so needle will jump up then go to infinity. Then reverse leads and you should see meter needle jump up and return again.
 
#12
Another important function of the condenser is to collapse the magnetic field of the coil very quickly to induce a higher secondary voltage and provide a ringing effect for a more intense spark.
 
#13
Another important function of the condenser is to collapse the magnetic field of the coil very quickly to induce a higher secondary voltage and provide a ringing effect for a more intense spark.
No sir, that is not correct. CFH was also in error when he talked about some "backlash." The only function of the condenser is to allow the primary side of the coil, called the low tension side, to feed into it, instead of leap across the point gap to ground. The induction of the spark is dependent upon the rate of change of the magnetic field, (Faraday's Law) and number of windings in the secondary determine voltage. In short sir, collapsing the magnetic field is accomplished by the flywheel moving beyond the magneto, resulting in no voltage. Collapsing the magnetic field is also accomplished by shorting the primary (low tension) side of the coil to ground. This is done by "kill" switch, or a shorted condenser, chaffing primary wire, etc.

Today I connected an Ohm Meter to the condenser.
Just to check for continuity and no response at all.
Although I did the skin test and there's current flowing.
Just no spark on any plug I connect, I used new plugs, old plugs from Tec four HP.
I can't figure out why this coil won't fire?
Reaper
There are several videos on how to test a condenser on line. You don't check for continuity, you are using your ohms scale on your meter to charge the condenser. The ohm meter uses a battery to check continuity, and you are charging up the condenser with that battery. Then you go to DC voltage on your meter, and you should see a small voltage. If you are using an analog meter, you'll want to be on the smallest DC voltage scale.

See above- ensure none of your wires from the mag primary side, (small wire of course) as well as your condenser lead are not chaffed and rubbing against bare metal.

If a skin test (I assume that means grabbing a plug wire) means you are getting zapped with the secondary coil (plug lead) then you have a bad coil. (Magneto) A shorted condenser will mean zero spark, just like you hit the kill switch. An open condenser will mean you have a weak spark at higher RPM, but the coil should still fire a spark plug when you pull start it.

I use an $8 spark tester. It allows you to test your plug, your spark, and your spark in a higher pressure environment in which it runs. Then there is no guessing.
 

cfh

Well-Known Member
#14
you can't test a capacitor with continuity. the charging and discharging theory can give some indication that it's working. but really you need an ESR meter to test it correctly. I could give you some readings on a new condenser with an ESR. but if you don't own one that would really be pointless. New condensers are $5. i would just buy a new one.
 
#15
@ReapersRide shoot me a PM if you need any further help my friend. I highly recommend procuring the spark tester as it takes out the guess work. And if you test your condenser as I indicated, you will be able to tell 100% if it is shorted, (lead to case) which IS tested with an ohm meter, and is the only failure mode that will prevent your engine from running.
 

cfh

Well-Known Member
#16
if he's worried that his condenser is shorted, he can just disconnect it. if the motor runs, that's the problem. but i suspect that isn't the issue....

i just worked on a motor where someone had incorrectly installed the condenser. it wasn't like it was mounted wrong. but they ran the wires in the wrong way. and for some reason removed the coil. after bolting it all back together, they managed to tighten the coil against the condenser wire, shorting it to ground.
 
#17

ELT

Active Member
#18
In college we charged the condensers, then handled them by the wire and tossed them to an unsuspecting buddy. When he caught it he got quite a jolt touching the case and wire.
 
#19
I am currently a waiting a condenser and points set to go with my new coil part.
If usps would quit jacking a round they were supposed to be here two days ago.
Reaper
 
#20
So I finally got my points and condenser, guess what?
I have spark on the plug.
Now I need to decide do I want to paint my new Tecumseh hs 40 block before I assemble it?
Reaper
 
Top