Toro 20372 w/Toro Engine

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Brandi

Member
I have a Toro 3072 mower with what I believe is a Toro engine model lc1p65fc engine. Presently it will start first pull and run perfectly. It will not restart when warm. It will sometimes stutter, cough and maybe start and run ok. I've run out of things to check. Is the attached photo
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multi.jpg
of the multi-meter reading of the coil to high?
 
If we’ve (the techs on this site) said it once we’ve said it a thousand times, TODAYS COILS CAN NOT BE TESTED USING A MULTI METER, You need special equipment to test them, due to Hall Effect triggers inside the coil. Easiest way for the DIY guts to test a coil is to disconnect the kill wire from a properly mounted coil and then check for spark. No spark, bad coil. Spark, you’ve got other problems.
Here is a service manual for your engine. https://www.toro.com/getpub/167041
 
Rivets said:
If we’ve (the techs on this site) said it once we’ve said it a thousand times, TODAYS COILS CAN NOT BE TESTED USING A MULTI METER, You need special equipment to test them, due to Hall Effect triggers inside the coil. Easiest way for the DIY guts to test a coil is to disconnect the kill wire from a properly mounted coil and then check for spark. No spark, bad coil. Spark, you’ve got other problems.
Here is a service manual for your engine. https://www.toro.com/getpub/167041
Click to expand...
Thank you for your reply and link to the service manual. I found this to be very informative. Page 8-9 and figure 270 & 271 shows how to check the this particular coil with a multi meter and the correct readings. Again, thank you.
 
I don't what the service say about testing the coils are not testable trigger wise.

Article by KE4AVB has the following which can be applied to even this coil.

The configuration of new Magnetron coil may look like they removed the triggering device but in fact it is just a redesign. Now to answer your question what is inside the coil.

1 ea 13mm x 34.5mm single sided circuit board.
5 ea SMD transistors.
8 ea SMD resistors, inductors, and/or capacitors.
(SMDs were destroyed upon board removal so actually identification wasn’t possible.)
1 ea D13003 transistor.

Primary Winding reading is 1.5 - 1.7 Ω.
Secondary Winding reading is about 6 KΩ +- several hundred ohms.

The kill terminal is directly connected to the non-ground side of the primary; hence, explains why you or anyone else can NOT test the primary trigger circuit. Otherwords this means you can not test to find out if a Magnetron coil is good or not without installing it in most cases; unless, you have a specialized coil tester.

The D13003 emitter is connected to non-grounded side of the coil’s primary via two SMD resistors in parallel with total resistance value of 0.5 Ω. (One these SMD resistors marked with the 1R0 code for a 1.0 Ω resistor, ½ watt size.) The collector is connected the coil’s primary winding that is grounded. The base is connected to the rest of the trigger circuitry. Now if other component in the trigger should fail you most likely will not see any different in the meter readings.

The coil’s transformer turns ratio is approximately 1 to 18 with secondary closest to the core.

In theory if the output D13003 transistor should short the collector-emitter junction and the coil’s primary winding is still good the ohms reading will drop to 0.25 Ω - 0.35 Ω. If the coil’s primary winding should short then the ohms reading should be near zero. If the coil’s primary winding should open then the reading will be well above 1.7 Ω. If anything else opens in electronics and the primary is good then you will still see the 1.5 – 1.7 ohms reading. Applying any voltage to the kill terminal would result in either coil’s primary winding shorting or opening due to high current experienced. Applying voltage also can short out the electronics thus making the coil useless. It is also expected that a cold solder joint connecting the external kill terminal to circuit board would lead to a non kill operation.

Also the high tension lead can be replaced if you wish to fight the glue considering the price of aftermarket versions of this coil.

This info was acquired through the destruction of the new OEM version of this coil. It also explains the configuration differences as they have gone to SMD trigger version.

Now for those that wondering why we put diodes in the kill circuit of the dual coil models it because of the feedback loop created causing one coil to kill the other. This explains why they are destroyed when 12V is applied as these is no built-in reverse bias protection. Now with this in mind you might think Kohler coils would be the same wiring. Not so as these diodes are incorporated into coil itself thus preventing many of the problems that the Briggs have because they don’t incorporate these diodes.
 
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