HELP... Solid iac LED when testing tach signal

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Tneitermayer
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Joined: Sat Feb 06, 2016 9:08 pm

HELP... Solid iac LED when testing tach signal

Post by Tneitermayer » Sat Feb 06, 2016 9:13 pm

This is my first post and I'm hoping for a little help. I just recently assembled jimstim 1.5 and everything went pretty good, or I thought it did. All my LEDs light when tested and nothing on my board gets hot when powered on. But when I test for the tach signal, the iac LED stays solid no matter where I turn the fine rpm pot any advice is greatly appreciated.

jbelanger
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Location: Quebec, Canada
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Re: HELP... Solid iac LED when testing tach signal

Post by jbelanger » Sat Feb 06, 2016 9:29 pm

Can you specify exactly how everything is connected, which jumpers you have and which wheel mode you're using (the DIP switch positions)? A picture might also help.

Jean
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Tneitermayer
Posts: 2
Joined: Sat Feb 06, 2016 9:08 pm

Re: HELP... Solid iac LED when testing tach signal

Post by Tneitermayer » Sun Feb 07, 2016 3:56 pm

Thank you for the reply. And I had the tach jumped to bottom of 10 pin for iac LED then I had number 9 of the 10pin connected to 12v header. I found the problem though. I had a bad solder joint on the number 14 pin on the cpu socket. I posted last night bc I couldn't find my volt meter to test the voltage. I bought a new voltmeter this morning and tested the rpm pots and realized it was showing correct at course rpm pot but the signal wasn't making it to the cpu. Redid the solder at pin 14 on cpu socket and all is well. Works like a charm. Now I need to order my msll kit.

jbelanger
Posts: 3655
Joined: Sat Oct 03, 2009 12:24 pm
Location: Quebec, Canada
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Re: HELP... Solid iac LED when testing tach signal

Post by jbelanger » Sun Feb 07, 2016 4:25 pm

Good to see you found your problem. A bad solder on the coarse RPM pin will have the effect of having a relatively high RPM so that will look like a solid LED since it's flashing too fast for your to see.

Jean
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