rigfire Posted September 19, 2006 Share Posted September 19, 2006 My recently aquired S75 fire truck has dual points and coils that are fried and cooked. Way to much heat. What is the cause? Wrong coil? For a temporary fix, we wired a ballast resisitor in front of the one coil we replaced. Was a friends idea that seems to work.Did stock wiring have a ballast resistor?Donny Quote Link to comment https://www.bigmacktrucks.com/topic/1545-ballast-resistor-for-points-and-coils/ Share on other sites More sharing options...
truxnut Posted September 20, 2006 Share Posted September 20, 2006 Most all of the 12 volt systems I have seen made before '55 or so use internal resistor coils. A 12V coil that uses a external resistor will fry the points and sooner or later kill it's self also. You can either replace with internal resistor coils or use regular ones with external resistors. Quote John Evans, Trucks & Dogs are expensive!! Link to comment https://www.bigmacktrucks.com/topic/1545-ballast-resistor-for-points-and-coils/#findComment-7635 Share on other sites More sharing options...
rigfire Posted September 29, 2006 Author Share Posted September 29, 2006 Most all of the 12 volt systems I have seen made before '55 or so use internal resistor coils. A 12V coil that uses a external resistor will fry the points and sooner or later kill it's self also. You can either replace with internal resistor coils or use regular ones with external resistors.Thanks for the help. Sorry for the late reply. Have been swamped at work. For the time being we have wired a ballast resistor in from of one of the coils. I am trying to find out how Mack stock wiring was configured.Donny Quote Link to comment https://www.bigmacktrucks.com/topic/1545-ballast-resistor-for-points-and-coils/#findComment-7760 Share on other sites More sharing options...
DWaits Posted September 29, 2006 Share Posted September 29, 2006 Thanks for the help. Sorry for the late reply. Have been swamped at work. For the time being we have wired a ballast resistor in from of one of the coils. I am trying to find out how Mack stock wiring was configured.DonnyDonny,I have a wiring diagram for the standerd E series chassis, it does not show the dual coil/distributor set up but it might be of some help.Let me know if you need a copy.David Quote 1948 Mack Pumper Link to comment https://www.bigmacktrucks.com/topic/1545-ballast-resistor-for-points-and-coils/#findComment-7761 Share on other sites More sharing options...
rigfire Posted September 29, 2006 Author Share Posted September 29, 2006 David,Thanks for the offer.Address is P O Box 14Midland, TX 79702I will gladly pick up any costs.Donny Quote Link to comment https://www.bigmacktrucks.com/topic/1545-ballast-resistor-for-points-and-coils/#findComment-7762 Share on other sites More sharing options...
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