520H tachometer wiring

[JD guy 1]

I lost battery / volt meter charge on 520H. Found partially heat scorched red charge wire connector at 9 pin connector. Cleaned up this  terminal of 9 pin connector and charge has come back to 14 volts.  When charge wasn't working, the tach came back to life but left when 9 pin connector cleaned up. Also cleaned 3 terminals of RR.  The double jump terminal of the RR (black from AC and grey to tach) are toward front of tractor / the center terminal on RR is red charge wire / the rear terminal is black from AC. Tach wont work after terminals cleaned and hasn't worked since I got unit several hours ago.  I read and saw post photo with jump wires on rear terminal of RR (toward rear of tractor). Will it hurt anything electrical to switch the front and rear connections on the RR - moving the jump connection (black wire and grey wire) to terminal  toward rear of tractor?  Tach didn't work since I got unit from a friend who had it from new and unit had RR connections with the jump (double) connection toward front of tractor (grey tach wire and black AC wire there) - red charge wire on center post - single black wire on rear most post). 

[lynnmor 7,706]

The factory position was the rear terminal for the tach connection.  I never thought it made any difference since it is just AC current to the two outside terminals, but swap them and retry.

[Ed Kennell 41,327]

  Either AC terminal should work.     Did you check and clean the terminal at the tach ?    Tach ground?

[JD guy 1]

Thanks for input on tach- I switched jump connector with grey tach wire to rear post on RR- tach came back to life!!