MSnS, MS1, V3.0 Hall setup PCB wiring for '83ZXT dizzy

[OhBilly]

I've been searching and haven't come up with an answer yet which leads me to believe that I'm either an idiot, or everybody else intuitively knows this. Or maybe both. Anyway...

 

My PCB is nearly built, just have to finish it off with wiring up the Hall trigger. According to V3.0 assembly instructions on the msextra site, I need to determine if the internal CAS is 5V or 12V. This will determine what jumpers I need to install as well as determine the value of R12.

 

I've followed the instructions on DIYautotune for their 280ZX turbo article which has helped a lot, but I can't seem to find this crucial bit of info.

 

Any help would be appreciated. Thanks.

 

Bill

[FlatBlack]

Something tells me 12V...

 

 

[OhBilly]

Something tells me 12V...

 

 

 

Well, you're probably right, but I don't think these schematics have anything to do with the CAS output voltage, do they?

 

The schematics tell you what wires need 12V power going to them for sure. But in reading about the Hall PCB wiring, it discusses Hall sensors and that some of them are 5V and some are 12V. It says that 5V CAS are more common and says if you are in any doubt, start with the 5V assumption and go from there. It also gives you directions for determining if your CAS is 5V or 12V, but it involves actually having the dizzy hooked up with power going to it. My dizzy is buried in the garage somewhere, probably hiding underneath some oil stained t-shirt.

 

Like I said, you're probably right (and thanks for the help) but I don't see how these schematics tell me what I need to know. Maybe I need to go back to MS school?

 

Bill

[FlatBlack]

Well, you're probably right, but I don't think these schematics have anything to do with the CAS output voltage, do they?

 

Once you have all of that connected then your ready to trigger MSnS. The following schematic shows how I connected MSnS to be triggered from the 83 turbo distributor. It was brought to my attention by another MSnS installer that the pullup resistor on the MSnS trigger(tach) line should be 1K instead of 2K like I use to have it. This will give a better trigger signal during cranking when the voltage can sometimes drop to around 9 volts.

 

http://forums.hybridz.org/index.php/topic/23244-megasquirtnspark-mssmsns-installation-guide/

 

I figured the 12V pullup resistor for the input back to MS would tell you what it is.

Edited August 30, 2010 by FlatBlack

[OhBilly]

I figured the 12V pullup resistor for the input back to MS would tell you what it is.

 

Nope, I'm not quite that bright.

 

But now I have another dumb question: Is R12 actually the pullup resistor, or something else? I just did another quick search and somebody mentioned that R12 IS the pullup resistor. Right now I have a 390 ohm resistor in R12, but MSnS says that for a 12V CAS the value of R12 should be 1K. Does R12 need to be 1K, plus "another" 1K pullup?

 

Thanks again.

[Matt Cramer]

The writeup on our site works for the standard value (390 ohms) of R12.

[OhBilly]

The writeup on our site works for the standard value (390 ohms) of R12.

 

Thanks Matt, that helps a lot. I've been reading a bit more and things are slowly becoming clearer, but it's definitely not easy... at least not for me. It seems there are multiple ways to make things work and that's part of where my confusion comes from.