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Grounded source coil
- Maico190
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Grounded source coil was created by Maico190
Working on my second ct1 restore and cant get spark from this one,
New coil, points, condenser and source coil.
Seems the source coil is grounded to the mounting plate, although I see nothing that would prevent this
as one end of the winding has an eyelet that fits beneath the mounting screw.
Once I remove the source wire from the condenser, there is no grounding issue (ie the points, condenser and attached black wire are ok).
Any help is appreciated, thanks.
New coil, points, condenser and source coil.
Seems the source coil is grounded to the mounting plate, although I see nothing that would prevent this
as one end of the winding has an eyelet that fits beneath the mounting screw.
Once I remove the source wire from the condenser, there is no grounding issue (ie the points, condenser and attached black wire are ok).
Any help is appreciated, thanks.
06 Jul 2022 09:10
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- alnarv
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Replied by alnarv on topic Grounded source coil
The source coil is supposed to be grounded at one end of the winding. The other end of the winding goes to the points and the condenser. With the the points closed, both ends of the coil (and condenser) are grounded. The magnets in the flywheel generate a current in the coil which is shorted to ground while the points are closed. When the points open, that current is suddenly transferred to the secondary coil, which steps up the voltage enough to spark across the spark plug gap. The voltage developed in the source coil is around 200-300V (but will work at as little 100V) but only for a few milliseconds.(it is called an energy transfer magneto) Your first basic check should be to see that with the points open, you should see approx. 1-3ohms resistance (the resistance of the wire in the coil) between the lead going to the secondary coil and ground. With the points closed, you should get 0 ohms. 9 times out of 10, the problem is dirty points not shorting the source coil when closed. Even new points have a coating which can prevent proper contact. Use some contact cleaner and pull a clean business card thru them until clean.
The following user(s) Liked this Post: MarkT, 1971DT250, RT325, AirborneSilva, Ht1kid, mike8162, Andy L, Sneezles61
06 Jul 2022 11:38
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- MarkT
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Replied by MarkT on topic Grounded source coil
Nice post Alnarv.
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1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
06 Jul 2022 12:56
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