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11-19-2012, 11:33 PM | #1 |
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Ballast Resistor not resisting?
Two ballast resistors, one is a new Mallory 700, no voltage drop. Measured resistance, there is no change in voltage ...reads 12.8 in and 12.8 out.
What am I missing here? thanks
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11-19-2012, 11:59 PM | #2 |
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Re: Ballast Resistor not resisting?
Are you measuring across it with a load on it ?
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11-20-2012, 12:43 AM | #3 |
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Re: Ballast Resistor not resisting?
Ohm meter not able to measure resistance of a couple ohms? I would measure without being hooked up to the battery or meter may be damaged. Once ohms measured, IR=E.
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11-20-2012, 02:54 AM | #4 |
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Re: Ballast Resistor not resisting?
Put the 2 in serires should read 6 and 6 volts
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11-20-2012, 08:58 AM | #5 |
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Re: Ballast Resistor not resisting?
If put a 1.5 ohm resister across 12 battery would draw 8 amps if it did,nt burn out.
If it burned out or not you would still rear 12 volts. If you put 2 in series of 1.5 ohms you would read half 6 and 6 volts. Use your OHM meter the mallory 700 is 1.5 ohms. Another way is add a 12 volt blub and 1.5 ohms and if the light goes on its good. |
11-20-2012, 09:51 AM | #6 |
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Re: Ballast Resistor not resisting?
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11-20-2012, 10:59 AM | #7 |
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Re: Ballast Resistor not resisting?
You won't measure a voltage change until the circuit is made and energized since there is no current flow. In an ignition system, the breaker points are what open and close the circuit so the points have to be closed in order to read the voltage drop of a component in the circuit. If you probe from one side of the resistor to the other when the circuit is closed, you will read the drop in voltage caused by that resistor. If probed on the out flow end of the resistor to ground , you will read the circuit voltage after the drop. If the circuit is open, you will read system voltage at the output side of a resistor since there is no load yet imposed on it. When the ignition system is operational, the current flow becomes pulsating DC which is half wave AC so that the coil & capacitor are faked into believing the system is an AC circuit and do their job at making a spark on the high tension side. The voltage pulsates fast enough that you can take a reading while its running and get a fairly decent reading of system voltage at the coil after it passes through the resistor. On a 6-volt system it should be somewhere around 3 to 4 volts. On a 12-volt system it depends on the type of coil you are using as to the voltage. Can type coil can be 6-volts if it was designed to be. Old style iron core coils should be 3 to 4-volts. If it is a late type coil that is designed to work on 12-volts, you won't need a ballast.
Last edited by rotorwrench; 11-20-2012 at 01:51 PM. |
11-20-2012, 11:59 AM | #8 |
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Re: Ballast Resistor not resisting?
I think the question is how to check a resister with only a 12 volt battery and a resister.
If you hooked neg and pos to resister across battery.If it was good or bad still would be the same.If good there would be current flow of 8 amps.If the resister was no good still read sourse. Putting 2 in line series the same each would read 6 volt. If one were no good you would read nothing. because you can,t get across battery. |
11-20-2012, 12:33 PM | #9 |
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Re: Ballast Resistor not resisting?
I checked the resistance and it is 1.8 ohms.
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11-20-2012, 01:48 PM | #10 |
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Re: Ballast Resistor not resisting?
How much voltage a resistor drops in a circuit depends on the resistance level of the resistor, the input voltage of the circuit, and the direction of current flow in the circuit then Ohms law applies as to all the variables if the circuit is sound. Voltage and resistance can change, but the way to take readings doesn't.
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11-20-2012, 01:52 PM | #11 |
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Re: Ballast Resistor not resisting?
Resistance is futile.
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11-20-2012, 01:59 PM | #12 |
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Re: Ballast Resistor not resisting?
Good one Mike.
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11-20-2012, 02:21 PM | #13 |
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Re: Ballast Resistor not resisting?
^^^^^
lol. |
11-20-2012, 02:28 PM | #14 | |
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Re: Ballast Resistor not resisting?
Quote:
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