LEDs dimly on (AFRO Error)

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Trump
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LEDs dimly on (AFRO Error)

Post by Trump »

Thanks, yes that is how I count them.

My other problem that may be on a new thread is that the LEDS for my shift, oil, log, and engine check are all glowing when not activated. Only a light glow but annoying at night.

Checks show the following with engine not running but ign on.

Batt V = 12,3V
V between MS3 output Nitro 2 (shift light) and earth = 2.4V
Current draw = 0.03mA

This is an old problem but now with extra LEDS.
Triumph TR3A. MS3X, IBT, Fully Sequential Injection, Wasted spark, 60-2 crank wheel.
arran
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Re: AFRO Error

Post by arran »

I think a normal 5mm led needs 100 to 200 mA to light up fully. If you are only driving it with 30mA that may be the problem. You will need about a 100 to 200 ohm resistor with 12v rail
RX7 Series 2 13B Turbo. Megasquirt 3 with 3X Expander and V3 CPU. Firmware 1.4.1
Knock module, twin EGT, real time clock, WBO2, full sequential fuel and spark
http://web.aanet.com.au/arran
Trump
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Re: LEDs dimly on (AFRO Error)

Post by Trump »

The LEDs are wired in with the appropriate resistors and function correctly. It is just that they stay glowing when they should be off.

The readings I gave are with the LEDs off.
Triumph TR3A. MS3X, IBT, Fully Sequential Injection, Wasted spark, 60-2 crank wheel.
Matt Cramer
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Re: LEDs dimly on (AFRO Error)

Post by Matt Cramer »

What output circuits are you using?
Matt Cramer -1966 Dodge Dart slant six running on MS3X
Trump
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Re: LEDs dimly on (AFRO Error)

Post by Trump »

Log - Inj G
Engine check - Inj F
Shift - Nitro 2
Oil - Tacho
Coolant - Nitro 1
Triumph TR3A. MS3X, IBT, Fully Sequential Injection, Wasted spark, 60-2 crank wheel.
arran
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Re: LEDs dimly on (AFRO Error)

Post by arran »

Can you check ground offset?

Is there a voltage difference between the battery negative and the megasquirt ground?
Is there a voltage difference between the ground point of the leds and MS ground?

No offence but you are working on an old English car which are not usually associated with good electricals :)
RX7 Series 2 13B Turbo. Megasquirt 3 with 3X Expander and V3 CPU. Firmware 1.4.1
Knock module, twin EGT, real time clock, WBO2, full sequential fuel and spark
http://web.aanet.com.au/arran
Trump
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Re: LEDs dimly on (AFRO Error)

Post by Trump »

How unkind! Are you suggesting old English cars have poor electrics.....
I restored this car and built a complete new wiring loom utilizing good connectors and earth returns.
For the MS installation I fitted a common earth point to which all earths for the MS installation are connected. That in turn is connected to the engine block and then to the battery earth. I have had no earth issues to date.

The earth returns for the LEDs are via the ECU. The ECU switches the LEDs by providing the earth.
There is 0V diff between the ECU earth and battery -ve.
With the ignition on, engine not running there is 2.4V between earth and the MS output. I would have thought this should have been 0V as the MS should not have activated that circuit, leaving it and open circuit. To me, that looks like there is some form or connection between the output and earth when the circuit is deactivated.
Triumph TR3A. MS3X, IBT, Fully Sequential Injection, Wasted spark, 60-2 crank wheel.
jsmcortina
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Re: LEDs dimly on (AFRO Error)

Post by jsmcortina »

I think that some of the "mid current" outputs may leak a little - so with a low current device such as an LED you may see some illumination.

James
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slow_hemi6
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Re: LEDs dimly on (AFRO Error)

Post by slow_hemi6 »

Yeah I had a led shift light like that. I could just see it dim at night when not activated. You just need to add some series resistance to get rid of that 30mA you are measuring in the off state. Probably about 100r or so should do it.
Find the Manuals up top under Quick links: Manuals. :RTFM:
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arran
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Re: LEDs dimly on (AFRO Error)

Post by arran »

Perhaps a couple of series forward biased diodes between the MS wire and the LED would help. Each diode is going to present about 0.7 forward drop, so 2 or 3 will get you the 2.something you need. This will also reduce the voltage driving the current through the resistor/LED, so you can compensate by slightly reducing the resistor value by 20 ohms or so because LED are a current driven device.
RX7 Series 2 13B Turbo. Megasquirt 3 with 3X Expander and V3 CPU. Firmware 1.4.1
Knock module, twin EGT, real time clock, WBO2, full sequential fuel and spark
http://web.aanet.com.au/arran
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