Blowing ballast resistor
- Thread starter blacktop
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68gtxman
I used to reMember
Too much voltage. The first thing I would check is the ground on the voltage regulator. After cleaning the ground, if it still doesn't start, try jumping out the resistor entirely. Start the engine and test the voltage then. If the voltage is not over 14.5 V, then try a new resistor again.
68gtxman
I used to reMember
You can check it anywhere. If it is 14.5 at the battery with the engine running, it's not going to be higher at the resistor (only lower due to resistance in the wiring harness).
nm9stheham
Well-Known Member
Do you have the older points distributor? If so, check the points gap; it should be around .017-.018" gap. Too small, and it will put excess current into the coil and ballast.
Now for the big questions: What PN of ballast are you using? And what is the coil model?
Does the car start and then blow the ballast? Then check as above at the battery as the car starts: see if the voltage is going way above 14 volts after it starts.
Also, check the voltage at the blue wire to the ballast with the car OFF. Make sure that there is 0 volts when OFF. If not, then what may be happening is that the ballast is staying hot and blowing while the car is off (and the points are closed all the time). When you go to start the car, the ballast bypass function of the ignition switch in the START position puts power to the coil and the engine will start, but then not stay running when you release the key from START to RUN since the ballast is already blown.
BTW, normal voltages at the ballast when running are .3 to .5 volts or so below the battery voltage on the blue wire, and 6-10 volts from ground at the wire from the ballast to the coil +.
Now for the big questions: What PN of ballast are you using? And what is the coil model?
Does the car start and then blow the ballast? Then check as above at the battery as the car starts: see if the voltage is going way above 14 volts after it starts.
Also, check the voltage at the blue wire to the ballast with the car OFF. Make sure that there is 0 volts when OFF. If not, then what may be happening is that the ballast is staying hot and blowing while the car is off (and the points are closed all the time). When you go to start the car, the ballast bypass function of the ignition switch in the START position puts power to the coil and the engine will start, but then not stay running when you release the key from START to RUN since the ballast is already blown.
BTW, normal voltages at the ballast when running are .3 to .5 volts or so below the battery voltage on the blue wire, and 6-10 volts from ground at the wire from the ballast to the coil +.
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Pretty sure the resistor will absorb any voltage spikes.
But a continuous off-draw will certainly shorten it's life
A high-current draw while running should kill the points first.
I"m going with;
D) a ballast with the wrong calibration, or a crappy part, or
E) crappy high-resistance connection(s) in the circuit; most likely right at the BR.
Best guess......
But a continuous off-draw will certainly shorten it's life
A high-current draw while running should kill the points first.
I"m going with;
D) a ballast with the wrong calibration, or a crappy part, or
E) crappy high-resistance connection(s) in the circuit; most likely right at the BR.
Best guess......
KitCarlson
Well-Known Member
Are you checking the ballast resistor, it just replacing? It could be a bullhead connection or other problem.
67Dart273
Well-Known Member
Seems like either the system running (charging) voltage is really really high, or that you have a bad / incorrect coil or incorrect ballast, or as said "there is some other problem."
As Dave (Kit) said above^^ are you actually checking the ballast? Maybe you have a bad terminal / connection, and when you replace the ballast, the bad connection gets "wiggled" back into contact. And yes, 'bulkhead connector' would be no1 on the list
As Dave (Kit) said above^^ are you actually checking the ballast? Maybe you have a bad terminal / connection, and when you replace the ballast, the bad connection gets "wiggled" back into contact. And yes, 'bulkhead connector' would be no1 on the list
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