I checked my wiring last night and my trailing wire had infact disconnected. So upon reconnecting it when I power up the MS, my LED's all come on but D16 is dimmer than the other 2, i've noticed this in the past when you first turn on the MS all LED's may dim then go bright. however now, D16 is dim, and if I disconntect the Trailing wire the LED goes out entirely. I still have no tach which indicated i still have no trailing. I noticed D16 was dim before and I had lost my tach, i moved the LED alittle and it was fine and last weekend when my tach died I resoldered D16. Now it would seem its not a simple a fix.

Is is posible the driver it shot or the LED itself ? Is there any way to test either the transistor or led other than replacing them ?


Sean

 

Answered this in your PM, thanks for reposting here....

It is likely that it's the transistor, or a short somewhere... maybe your pullup resistor is touching something it shouldn't?

Also check for solder bridges on those same components...

 

Well I've visually checked the pullup resistor and its not contacting anything it should be. My only guess is the transistor as i've had issues with this LED and my tach going dead before.

If my trailing wire had shorted it most likely would have killed the transistor? What is odd is that the LED does get power and does light up but its only dim. Is there a way that you know of to test the trailing ignighter wire for a short ? I'm considering running a new wire since Im still using the factory one. Another thing, the LED goes off if I disconnect the trailing wire from D16 is this expected behavoir ? Logically if the LED goes out once the wire is removed there would be a problem with polarity ?

 

I believe the LED being dim is fine when there's no power going through the transistor yet. You'll see this when the MS starts too. If it just stays dim it means that for some reason the transistor is unable to turn on the LED, which is what makes me think the transistor is shot. It could also be the LED or your wire, but I think it'd be easier to replace that transistor first.

 

I'll see if I've got a spare one lying around tonight and give it a shot. Thanks i'll let ya know what I find.

Sean

 

I replaced Q8 and D16 and I've got tach again. The LED is dim still though.... very odd. Perhaps its the batch of LED's I got ... its the same part# from digikey as listed in the BOM list. Thanks for the help Ken

Sean.