Just built my JimStim ...tach signal test question

[nismoautoxr]

Tested the LEDS and all work according to the test at the end of assembly . Then moved on to testing the primary and secondary tach part. I am not sure what I should see here. Going by the instructions a blinking should be observed and as the RPM pot is turned from full counter to clockwise the blinking frequency should increase or at least that is what I interpreted.

What actually happens with my unit is that it starts off very dim at fully counter and increases in illumination intensity as I go clockwise and is somewhat progressive untill I get about a 1/2 to3/4 turn or so in and then its pretty much full bright. I wouldnt call this a blink . I did observe what Id describe as a "timed" flicker at one point on the pot turn .

Does this sound out of the ordinary? Not new to MSextra for sure ...just new to the Jimstim cause up to now ..my present ECU (DIYPNP) didnt have the capability of being tested with the stim so I never bought one but since I am about to assemble an MS3 I decided to buy a JimStim too. Is it working as designed or should I be looking for a problem?

[kjones6039]

Does this sound out of the ordinary?

Nope! Sounds perfectly normal to me assuming it does flash at lower rpm. As rpm increases the led will appear to light fully.

Sounds just like mine.

Ken

[racingmini_mtl]

There are two RPM pots on the JimStim. If you set the coarse RPM pot (marked RPM C) fully counterclockwise and only use the fine RPM pot (marked RPM FINE), you should be able to see the LED flash. If you use the RPM C then you won't see much flashing as RPM increases too quickly to something the eye can't see.

Jean

[nismoautoxr]

Gotcha. I tried it again using the fine RPM pot and it does work . I guess when the instructions used the term "blinking" I expected it to be defined on-off blink rather than a change in intensity from dim to brighter . Wanted to make sure I was seeing what I should . Thanks for the clarification.

[racingmini_mtl]

Actually, it should be distinct on-off flashing if everything is correctly connected and functioning as it should. The duty cycle of the wheel pattern doesn't change with RPM so the intensity should not change either; it's just that at low RPM your eyes can see the individual pulses.

If you simply see a difference in intensity then you need to go back to the test and check that you are following exactly every step. Make sure your JimStim is NOT connected to the MS and that it is resting on a non conductive surface. Check that every jumper is set as per the instructions. And make sure nothing gets hot on the board.

Jean

[nismoautoxr]

OK let me describe exactly how Im testing it. NO jumpers installed , nothing hooked to it but the power adapter (9VDC/1000ma) . Set all dips to off which according to the test simulates distributor mode, a jumper from pin10 to primary tach header pin closest to the pots and furthest from the text "primary tach" , a jumper from 12v (next to the regulator0 going to pin9. Turn all pots counter, turn on power switch.

What is observed with all pots counter is a dim but solid IAC2 led. Turning the fine RPM pot clockwise the brightness of led gets brighter but does nothing but that untill I get to about a 1/4turn CW then it begins to go bright-dim and from there only the frequency of the bright-dim changes but definitely not an on-off.

I can get an on-off BLINK if I turn dip2 or dip8 on with all others off . I get the exact behavior if I do the test with IAC1 led as well. Bear in mind I have not even built the MS3 yet therefore I dont have anything to connect the stim to right now . Im just simply running the functionality tests at the end of assembly.

EDIT: I have absolutely no heat coming off of anything . The regulator ,polyfuse,and CPU are all room temp or maybe just a little warm to the touch but not hot. No magic smoke or odors .

[racingmini_mtl]

So you're saying that with all DIP switches off, you have a dim LED when it should be off but with either #2 or #8 on, you don't see that? Are you sure you are connected to the primary tach header and not the secondary?

With switch #2, you would be using the 4/1 CAS mode which does have a secondary tach signal (the basic trigger doesn't). However, I don't see why you would get what you see with switch #8.

You might want to have a look at the solder joints on the transistor Q1 to make sure there's no bridge or any flux residue.

Jean

[nismoautoxr]

found the problem. I failed to solder pin 7 of the processor socket into the board LOL. OOPS....works as it should now,

[racingmini_mtl]

Good to see you found and solved the problem. However, I have a hard time seeing why it would manifest itself the way it did.

Jean

[nismoautoxr]

dunno but thats all I found and fixed and now it blinks on and off and gets faster with clockwise tunring of the fine pot and is all the way out when turned fully counter with all switches off. <shrug>