Can you fry an msd box. I have a 73 340 duster with a 7 al msd box ,in the fall put it to sleep for the winter all ran well. This spring asked the grand son to put the charger on to get the battery fully charged. by mistake he put the red on ground and black on pos. Now we have no spark ,no power to the pos. side of the coil. Now with new battery have proper volts to the box same leaving the box .tested coil it is good tested dizzy it is good. with key on no power coming out of box to supply the coil. Also checked fuses, neutral safety switch. The car came with the 7 msd I am not looking for a fast car I am a good shape 70 just looking to drive a car use to have. Thinking of going back to old system but would like to solve this first and sell the msd system