A few weeks back I had some electrical problems. It was posted then and all is good now. Here's the time line. I suspect that searching for the problem I may have caused another issue.

The ignition fuse failed repeatedly after the first run on a Saturday evening in Gainesville. Even though my wiring is relatively neat and labeled I was unable accurately diagnose or isolate the problem there.

At home a couple of days later in the cool shade I began to isolate circuits individually until the engine would run with out ignition fuse failure. Disconnecting the Field wire from the ignition switch allowed me to get three starts without failing the fuse before it entered a no start condition again.

The alternator was the root of the problem I'm sure with the rectifier missing diodes, the diode trio melted, and the regulator failed. The stator and rotor were both good. Remember the is a 12SI I spin backwards.

Still no start. So I borrowed a Grid System from jmarkaudio. By changing in and out combinations it would run on the 7220 power grid. Mine would not feed 12 volts back to the red 7730 controller. Problem solved. The fault history in my 7730 did show excessive battery voltage. Old regulator made 18.4 volts at testing. It's a 12 volt piece.

Okay so where did I go wrong in the diagnosis?

Was it just the alternator as the original problem? Did I make it worse by isolating the Field wire and then running the car? Maybe there wasn't sufficient ground from the engine to the frame or alternator to the frame? There is now BTW.

I can't imagine the Grid not being able to handle 18 volts.

So what do you all think?

quote:

Originally posted by nomad: So what do you all think?

If you find the Grid 7720 has failed, do send it back to MSD for repair.

7730 Grid will show / log a high voltage error if over 18 volts, but I believe it will continue to run in this error condition. I’ve seen this error logged in other 7730’s.

Curious. What was the reasoning of running a separate field wire that you decided? There are
10/12 Self exciting Alt's available. Install and go. The internals will fail and melt over 15.8 on
a 12 system. Just curious.....

I prefer the 3 wire set up better.

One wire installations will draw amperage when off. Unless you wired the 1 wire through a relay or a solenoid, in order for the motor to kill when you flip the main switch off, it needs to be connected directly to the positive post on the battery. If its connected to the car side of the master cut off switch it continues to feed the ignition and the car stays running. If you connect a 1 wire alternator properly for the master cut off to function as it should, the alternator wire will need to go direct to the battery positive post and it will draw a tiny bit of amperage when the car isn't running. That's how my 1 wire setups were wired for most of my years of racing till i got sick of the batteries going dead when parked in the trailer and not on charge. So i installed a solenoid on the alternator heavy gage charge wire that turns on and off with a switch.

I wouldn't need the solenoid if i used a regular 2/3 wire configuration and turn the alternator on with a switch from the panel. They don't draw in this configuration, at least that's been my experience.

quote:

Originally posted by Triple Nickel:
One wire installations will draw amperage when off. Unless you wired the 1 wire through a relay or a solenoid, in order for the motor to kill when you flip the main switch off, it needs to be connected directly to the positive post on the battery. If its connected to the car side of the master cut off switch it continues to feed the ignition and the car stays running. If you connect a 1 wire alternator properly for the master cut off to function as it should, the alternator wire will need to go direct to the battery positive post and it will draw a tiny bit of amperage when the car isn't running. That's how my 1 wire setups were wired for most of my years of racing till i got sick of the batteries going dead when parked in the trailer and not on charge. So i installed a solenoid on the alternator heavy gage charge wire that turns on and off with a switch.

A solution for this is to use the Cole Hersee 75912-BX DPST master disconnect switch which allows you to disconnect the alternator along with the battery. Moroso rebrands it as #74108 and charges a premium for the name.

quote:

Originally posted by markemark:
If you find the Grid 7720 has failed, do send it back to MSD for repair.

I thought the Grid was disposable/not repairable upon failure?
Did MSD change their policy, or am I not remembering correctly, (I thought that was a source of some concern in a previous discussion about that on here)?

quote:

Originally posted by FootbrakeJim:

quote:

Originally posted by markemark:
If you find the Grid 7720 has failed, do send it back to MSD for repair.

I thought the Grid was disposable/not repairable upon failure?
Did MSD change their policy, or am I not remembering correctly, (I thought that was a source of some concern in a previous discussion about that on here)?

The 7720 is repairable. The 7730 is a throw away if not a firmware issue.

A substantial portion of the 7730 cost is the included wiring. It would be nice if you could purchase the 7730 controller by itself at a discount.