MicroSquirt.com read only forum (Jan.15,2018)

I have been reading a lot lately abotu people putting a resistor on their Innovate LC-1 output signal to the MS... why, and what do you do?

Jon k wrote:I have been reading a lot lately abotu people putting a resistor on their Innovate LC-1 output signal to the MS... why, and what do you do?

Well, word is that one should install a 470Ohm resistor in series with the output of the LC-1 to the MS-2, although I can't really see why unless it is to change the filter characteristics. And if so, the same can then be achieved by increasing R10 to 1K5 Ohm - its just more practical than physically wiring in another resistor.

Until we get a categoric "its not necessary" I would suggest you go with R10 - 1K5. (It works well)

The resistor is to protect the DAC, digital to analog, part of the LC-1. Also stressed by Innovative is to have the LC-1 ground at the same point as MS.

Mike Simard wrote:The resistor is to protect the DAC, digital to analog, part of the LC-1.

Is that function not adequately performed by R10?

The idea is not to labour the point but perhaps to test the bit of residual electronic knowledge I have left....

Where does it say to do this? I have a MS-1 v3 and I don't have a resistor installed, I just have an ordinarily built MS and LC-1 and it seems to be working fine.

Edit: I just looked over the V3 assembly and step 47 says to put in R10 which is a 1.0KQBK-ND, 1K, brown-black-red, which I have done. Am I ok then?


Won't adding a 1500 ohm resistor (what wattage?) limit the voltage the MS sees? So how do I re-configure the input? I am a little bit confused, as I have been running my MS with LC-1 (not 'running' it but have it installed and just not hooked to injectors) for about a month now... my LC-1 seems to be fine.

I have a V3 board and LC-1.
It was working fine with no extra resistors, then yesterday I put in a 470 K Ohm (my mistake, I remembered wrong from the post I read) and it works the same as before.
Just a data point for yall.
Perry

R10 has nothing to do with the O2 input. Like mentioned the resistor is to protect the LC-1. The older ones died easily. The design was changed and the DAC is protected against anything but a 12v short. I do'nt know when they stared shipping the improved design. I had two die and was then sent the new "version".

Searching will bring up a lot of info. Here a link to Innovates' website mentioning the MS.

MiseryQ wrote:Searching will bring up a lot of info. Here a link to Innovates' website mentioning the MS.

The Innovate site says as follows:
"High-impedance inputs, like those found in the current version Megasquirt fuel computer, can create problems with the LC-1 because the input caps act as dynamic shorts. The easiest fix is to add a 470 Ohm resistor in series with the analog output of the LC-1."

I stand to be corrected but I believe this statement to apply to MS builds prior to the V2.2 board which possibly did not have the R10/C10/R11 combination of the V3 board and the R1/C2/R29/D11 circuit on the V2.2 board. From the Innovate statement I deduce that the MS O2 input had a cap ONLY which WOULD act as a dead short for LC-1 output containing higher frequencies and therefore WOULD serve to protect the LC-1 rather than MS. Coming to this understanding, I do believe the 470Ohm resistor is stricly speaking not required for V2.2/V3 builds and also explains why some reported "all OK" without it (unless Innovate meant that R10 and R1= 1K was not of high enough resistance). However, this resistor may still serve a minor purpose by protecting the LC-1 ouput if a dead short should occur between this 470R and the MS input (unlikely as it may be....)

I have a newer LC1 and V3 board. No problems without resistor.

bluetrepidation wrote:I have a newer LC1 and V3 board. No problems without resistor.

Same - I got my LC-1 and MS @ Christmas time... I don't appear to be having any issues...


Is there a way to tell your LC-1 is "new" release? What are the probs anyway? I can't tell if I am fine because I don't know what to look for.