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-   -   Megasquirt Detonation above 7k? MS-I resolution or modified CAS the culprit? (https://www.rx7club.com/megasquirt-forum-153/detonation-above-7k-ms-i-resolution-modified-cas-culprit-745430/)

Jobro 04-15-08 07:57 PM

I think the solution is to get a normal cas and build the 2nd vr circuit as well as trying to find if some condensors (i think thats what they call them) help. I believe they are just caps to ground from the power of the leading and trailing coils to ground.

Someone else suggested me do that when I was having resets.

I can confirm that the circuit in h4infs guide works, I built it (on breadboard) and scoped it today with a freq gen. I also have one built in my proto area but that isn't working :wallbash:


Will the board ever be changed to have 2 vrs and 2 halls?

2Lucky2tha7 04-15-08 09:31 PM

Now, I must admit. I never knew how to "exactly" build the 2nd circuit.:dunno: I've seen the diagram, but I honestly do not understand it. I'm more of a visual learner. I was able to build and modify my entire MS, but I can't read "electronic diagrams".:rolleyes:

muythaibxr 04-16-08 01:44 PM

I believe you can buy a board that does the 2nd VR with an lm1815 pretty cheap from glen's garage, and possibly from diyautotune as well.

Ken

Jobro 04-16-08 03:19 PM


Originally Posted by 2Lucky2tha7 (Post 8097725)
Now, I must admit. I never knew how to "exactly" build the 2nd circuit.:dunno: I've seen the diagram, but I honestly do not understand it. I'm more of a visual learner. I was able to build and modify my entire MS, but I can't read "electronic diagrams".:rolleyes:

Heres the part list

330pF ceramic cap
0.33uF tantalum cap
0.1uF poly prop cap x2
0.01uF poly prop cap

1k resistor
4.k resistor
82k resistor
18k resistor

lm1815n integrated circuit (it has 14pins) (x2 if you are clumsy)
dip socket incase you toast t he lm1815n

Soldering iron
flux pen
solder
solder pump (sucker)

Start by buying all that and another cas, and I'll help you through it assuming you have room in your proto area.

The Griffin 04-17-08 12:27 AM

http://www.jbperf.com/dual_VR/index.html

Is another option for just a dual VR condioner board(small). Jean is quick to answer questions on his boards at the MS-extra site.The only drawback is you have to buy the components elsewhere like digikey,Mouser etc. Unlike Glen's or DIY where you can buy the complete kit in one shoot.

2Lucky2tha7 05-27-08 11:35 PM


Originally Posted by Jobro (Post 8100266)
Heres the part list

330pF ceramic cap
0.33uF tantalum cap
0.1uF poly prop cap x2
0.01uF poly prop cap

1k resistor
4.k resistor
82k resistor
18k resistor

lm1815n integrated circuit (it has 14pins) (x2 if you are clumsy)
dip socket incase you toast t he lm1815n

Soldering iron
flux pen
solder
solder pump (sucker)

Start by buying all that and another cas, and I'll help you through it assuming you have room in your proto area.

Why the slight variation in the list as compared to this one?
http://www.msextra.com/manuals/MS_Ex...nual.htm#2ndVR
Just curious, as I will need to build one within a week or 2 for my brother's car. I want to use the smd 3.57 board, but until I know for certain what to modify, I am hesitant to buy it instead of the 3.0 board. My "expertise" is still only limited to the 3.0 board with the MS-I processor and running the modified CAS, thus the reason for all my newbie questions.

muythaibxr 05-28-08 10:07 AM

The lm1815 circuit in the manual is for running a 36-1 wheel.

The one you need only has one tooth per rev, not 36, so the circuit is changed to both avoid noise, and to create a square-wave with a pulse-width long enough for the MS to catch it.

Ken

2Lucky2tha7 01-16-12 07:23 PM

Late follow up:
When I had the engine apart over 2 years ago, I found the problem. Turns out a corner seal spring was missing. Don't know how or why, but that was it.
Figured I should clarify....even after almost 4 years.


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