FYI.   I just found an online manual for this dyno.   It was also sold under SnapOn brand.   Quick read might answer some of my questions about wiring.   

https://www.snaponequipment.com/common/serviceparts/mahaasmhp.pdf

Reading through the manual each coil is rated 96V.   In this case I am planning 2 series - 2 parallel connection to give me 192V total.   will plan to pair the coils 180deg across for parallel.   

Any Concerns here with this proposed setup?  

I also found that there is an integral speed sensor.   In this case, I answered a question above about mounting the external speed sensor.  I will just use the existing one.   I will also use the integrated temperature sensor on the eddy current drive as AUX in.   Hoping I can set software limits based on temperatures.   I will just need to figure out calibration factors for each of these sensors.   

I spent some time going through the coils today.   They are already wired 2P-2S.   Then I started questioning my electrical math.   Each coil rated 96V.   Connecting in parallel does not change the voltage rating.  It just divides the coil resistance by half.   Then the two sections in series will add voltage to get 196V and meet my target.   The two coils in series then restores the wire resistance back to original.   Is my logic correct?   

Hi, and welcome!

• • cooling fan for retarder
    • Can I use an I/0 to drive this fan?  I suppose I need to check if it will run on the 5V output.   
• No that does not work. You need a much more powerful fan. You can buy a relay board that you can control from YourDyno. They are called KmTronic, this one for example: USB Relay Controller - Eight Channel
  • Speed reference
    • I need to add the speed sensor wheel and actual sensor.   
    • Does this get mounted to retarder or rollers?  
• It must be mounted on the same axle as the retarder. Anywhere on this axle is fine 
  • RPM
    • I plan to add an RPM inductive pickup.   
      • high tension wire inductive pickup is straightforward.   
      • Does anyone have suggestions for one that will work with COP setups?
• Buy the Innovate motorsport inductive pickup: https://www.innovatemotorsports.com/inductive-clamp-kit-for-use-with-lm-2.html. It is recommended to change to a shielded cable.

 Is it possible to upload photos?  Or do I need to link from external site?  

 You can upload one photo per post

Cheers

Thank you for the response.   

Related to the cooling fan.  I meant use an I/O pin to drive a relay and then setup temperature control to trigger relay.   I have since reconsidered.  It is easier for me to wire a 220Vac fan to the input and just have it always blowing air when the dyno is powered up.   

I am also swapping the center lift bar gas solenoid to a 22oVac so that I an add an external switch on the outside panel for load/unload.   Easier to have manual control than software control.   Especially considering it will be manual to strap the car down.   

Thank you for the suggestion on the Innovate Motorsports RPM pickup.   I use their WBO2 sensors in most of my EFI installs.   I will plan to wire that to RPM2 inputs.   

I am using RPM1 input for the wheel speed sensor (roller speed) that is existing on the dyno.   i have to verify the tooth count.  

Are the ThC inputs for Thermocouples or Thermistors?  if Tc - what type?  k-type?  

Also, for reference.   Jostein answered a question I had posted on the DIY Dyno FB group.   The current retarder has 4 coils is wired 2S2P.   He suggested that I wire all 4 coils in series (4S) and the drive them with 192V output on the DC supply.   I have already connected the coils.   

Thanks for all the help.  I hope to have most of it wired tomorrow so I can power it up for the first time.   then I have to figure out how to calibrate the load cell.   Until next time...

@jpnovak yes, manual control is often the best for things that anyway are manual. No need to run it through the software.

The Innovate clamp connects to EngRPM (not RPM2). 

Yes, the thermocouples are K-type (isolated).

Cheers

The DC supply and control box are now wired.    

I cut an access panel in the electrical box lid so the fins of the supply stick through.    Also planning a cooling fan at the top to pull air across the compartment.     

The eddy current coils are now wired 4 in series.    I measured 45Ohm nominal across each one.    

Can someone verify the tooth count for Maha speed sensor?   I think this is 120 tooth. 

I cant get the access panel off to count.     There seems to.be problems where someone in the dynos past life used Standard hex keys instead if metric.   Most of the hardware is stripped.    I just have not had time to pull amd replace.    

Thank you for clarification.   I might have downloaded older manual.   I did not see engRPM in manual.   But it is on the control box.   I want RPM for engine speed lock relative to EFI column for load cell tuning.

I was able drill some hardware and pull end cover.   

For reference the tooth count is 100.    

Now I have to decide if a VR to 5V converter board is easier than mounting the toothed wheel and Hall Effect sensor I bought with my Yourdyno setup.   Traveling all week for work so lots of time to think.