Digiplex testing

Looking for options to have Digiplex units tested. Does anyone have a recommended source or experiences they want to share?

Thanks

 

David Feinberg at Sarasota Italian Garage:

https://www.sarasotaitaliangarage.com/ferrari-parts

but he'll probably suggest that you just change to his (much more modern) Digiplex replacement units

 

Thanks Steve

 

The digiplex is pretty simple. All it does is take the signal from the RPM sensor and the TDC sensor to determine how often and when to momentarily ground the (-) side of the coil. With no spark at all, if the problem is on the primary side, there is either no power to the coils and digiplexs or the coils aren't being grounded. That is why you need to look at the coil trigger (at pin 11 on the digiplex or at the diagnostic port). If the coils have power and the digiplex is switching the (-) side between open and ground and you still have no spark the problem is on the secondary (high voltage ) side.

On my 85 QV this is what the trigger signal looks like when they is good spark.



This is what it looks like when there was no spark due to a carbon track between the rotor and the distributor shaft.




In both cases the horrizonal part of the trace is 12V. Then you can see it basically drop to ground (short slanted part) then rise sharply and decay to 12V differently depending on how the coil discharges,.

 

I wish I could figure out how to do this with my scope. I have a scope but don’t know how to use it.

 

What kind of scope? Look for an online manual.

 

I have a SnapOn Counselor II. I have the manual, but I just can’t seem to make it work. It does not show data. I am wondering if there is possibly something wrong with the scope.

 

"The digiplex is pretty simple. All it does is take the signal from the RPM sensor and the TDC sensor to determine how often and when to momentarily ground the (-) side of the coil."

Hmmm...seem like if you could just come up with a mechanical "switch," maybe inside the distributer using a small, spring loaded set of contacts and a capacitor to reduce any arcing, you could do the same thing without all the electronic stuff! I'll bet someone could make a fortune!

OK, seriously, I agree with John's comments but it seems like all the relevant tests have been done and they indicate that everything is working properly...except, it isn't.

"I have a SnapOn Counselor II. I have the manual, but I just can’t seem to make it work. It does not show data. I am wondering if there is possibly something wrong with the scope."

Tobygaff, it seems that the gods of electricity are quite annoyed with you for some reason...

 

Ha! I know right! I bought this scope on a whim because it looked handy if I needed to troubleshoot an issue exactly like this. But this is the first issue that has come up. So now I need to figure out if it works or not!

 

Wow. At least it's period-correct.

 

I know., but that is exactly why I bought it. The cars I like have distributors and cassette players!

 

I completely agree. Obviously they must also have manual shifts!