Yesterday's Tractor Co.
Shop Now View Cart
   Allis Chalmers Case Farmall IH Ford 8N,9N,2N Ford
   Ferguson John Deere Massey Ferguson Minn. Moline Oliver
Classified Ads
Photo Ads
Tractor Parts

Discussion Forums
Project Journals
Tractor Town
Your Stories
Show & Pull Guide
Events Calendar
Hauling Schedule

Tractor Photos
Implement Photos
Vintage Photos
Help Identify
Parts & Pieces
Stuck & Troubled
Vintage Ads
Community Album
Photo Ad Archives

Research & Info
Tractor Registry
Tip of the Day
Safety Cartoons
Tractor Values
Serial Numbers
Tune-Up Guide
Paint Codes
List Prices
Production Nbrs
Tune-Up Specs
Torque Values
3-Point Specs

Tractor Games
Just For Kids
Virtual Show
Museum Guide
Memorial Page
Feedback Form

Yesterday's Tractors Facebook Page

Related Sites
Tractor Shed
Ford 8N/9N Club
Today's Tractors
Garden Tractors
Classic Trucks
Kountry Life
Garden Tractors Discussion Forum

Re: 1970 14 hp kohler no spark

[Show Entire Topic]  

Welcome Guest, Log in or Register
Author  [Modern View]
joe csuti

11-28-2013 13:57:48

Report to Moderator

If the the condenser is internal in coil which I more & more suspect,it probably serves the same function as a condenser in a normal points ign setup in that when points open a spike voltage up to 3 times supply voltage is generated for a fraction of a second as magnetic field in coil is collapsing,this spike voltage is induced into secondary winding of coil & boosts hv output,in addition spike also traveles back to source(points)the condenser across the points absorbs the spike voltage & reduces voltage in coil primary to as close to zero volts as possible before the next points cycle so you get max voltage buildup in primary of coil next time points close,in addition condenser prevents point burning/drawing an arc when points open,if condenser wasn't in circuit or if condenser open/shorted voltage would stay high in coil primary & have the effect of points staying open/closed all the time & no high voltage will be generated.

As far as solid state ign,I think the condenser in series with primary of coil is there to function as a buffer to protect scr in trigger so spike voltage from coil doesn't exceed piv voltage rating of scr,it may also function as a disconnect on load side of scr as usually when you use an scr in a DC circuit circuit when the scr turns on it will stay on an act as a latching relay till source voltage or load disconnected from scr so same can turn off,I found this out the hard way many yrs ago when I added foil defroster grid to rear window of my van,instead of buying a electro-mechanical relay I used a 20A solid state sw I had on hand,I killed battery in van 3 times in 2 days & couldn't figure out why,came to find out soild state sw was staying on/latched & powering defroster grid all the time after solid state sw turned on,even though sw on dash for sw turned off,only way to turn sw off was to disconnect load/supply voltage for a second or two.

As far as checking coil with a normal coil tester designed for 12v coils I don't know,it's something that would have to be tried,with condenser in series with coil primary if condenser open tester wouldn't work on coil,if condenser shorted it may give a false indication as to condition of coil or if coil working correctly,the only way I can think of to test solid state coil is to take a know good coil & see how/if it works with tester & use that as a standard when checking other coils.

Years ago I gave a thought to building a tester for trigger module/coil,however since that time either I no longer have engines with solid state ign or converted same to point ign as solid state systems went bad,just converting is an adventure in itself.

[Log in to Reply]   [No Email]

11-28-2013 16:03:10

Report to Moderator
 Re: 1970 14 hp kohler no spark in reply to joe csuti, 11-28-2013 13:57:48  
Actually, I believe the capacitor in those Kohler EI coils gets charged voltage from the stator that gets rectified by diode(s) in the trigger module, and when the SCR is triggered it discharges the capacitor through the coil and makes the spark, a primitive CD ignition system.

[Log in to Reply]  [No Email]
joe csuti

11-28-2013 19:18:21

Report to Moderator
 Re: 1970 14 hp kohler no spark in reply to Bob, 11-28-2013 16:03:10  
You may be right,I've never put a trigger module on bench & tried to do open heart surgery on it & figure out how it works,what does strike me as strange is condenser is non polarized,I would think same would have to be polarized to operate correctly in a cd system,but I may be/am probably wrong,it just may be another one of those mysteries of life/electronics.

[Log in to Reply]  [No Email]

11-28-2013 22:01:13

Report to Moderator
 Re: 1970 14 hp kohler no spark in reply to joe csuti, 11-28-2013 19:18:21  
HOW do we know the capacitor that's epoxied inside the coil is NP?

I've got a bad coil lying on the back of the bench somewhere... I'll try to find it and dissect it some cold and stormy day this winter when it's too cold to do much else!

[Log in to Reply]  [No Email]
joe csuti

11-30-2013 03:01:05

Report to Moderator
 Re: 1970 14 hp kohler no spark in reply to Bob, 11-28-2013 22:01:13  
I'm just going by symbol used in trigger module/coil drawing,the way condenser symbol drawn would indicate a non polarized condenser as there is no pos(+)end,the symbol is the same as a symbol for a condenser used in AC circuts for motor start condensers,line filters etc which are non polarized.

[Log in to Reply]  [No Email]
[Show Entire Topic]     [Options]  [Printer Friendly]  [Posting Help]  [Return to Forum]   [Log in to Reply]

Hop to:

Fast Shipping!  Most of our stocked parts ship within 24 hours (M-Th). Expedited shipping available, just call! Most prices for parts and manuals are below our competitors. Compare our super low shipping rates! We have the parts you need to repair your tractor. We are a company you can trust and have generous return policies. Shop Online Today or call our friendly sales staff toll free (800) 853-2651. [ About Us ]

Home  |  Forums

Copyright © 1997-2016 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy

TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters