If you have noise issues, it may be the RPI or the connection to the RPI.


 

John Bostwick

TVWBB Wizard
I never really ran into this before so I thought I would make a post about my recent build.

I was making a HM and I got it up and running and the Thermocouple was just giving me all kinds of noise. I first thought it was the new amps I recieved from a vendor I never used before, so replaced that and no difference.

Again, I thought it was Thermocouple circuit and I replaced all the smd parts and even purchased new ones, as some of my parts I have had for many years, no change in the noise. At this point, I was pulling out what was left of my hair. I ordered some solder flux to make sure my joints were good and soldered up another board and the same issue, temps fluctuating and noise.

I looked at every solder joint with my digital microscope and I also had to replace my soldering/air station during all this because the solder iron finally stopped working after close to 10 years :(.

Everything looked good. My Hm boards are custom made board so the traces different then the regular boards and I have added a 3 pad switch attachment for use with the Adapter boards, I was starting to think they were the cause, even though I had been using the same design for many years now and zi always get them made at OSHPARK. Maybe they changed something, as the last time I had boards made, I also had some noise issues.

Oh, I even purchased a K-thermocouple digital probe unit that came with 3 or 4 probes for $30, on Amazon, just to see if my Thermoworks probe was causing any issues and the noise was also the same on them, also.

Recently, I made an Adapter board for a customer and I tested it on the same board that had the noise and it worked perfectly fine, when I switch over to it, and when I switched back to the main Thermocouple connection right back to noise again.

When it comes to noise, I am basically at a loss without have a scope to test and to help locate the noise, but usually I have had successfully fix noise issues and usually it's just a bad solder joint.

Since, I had multiple Rpi's I figured I would try out different one, and will doing that I realized when I was touch the Rpi connection the noise went away 😳. Hmmm, I started looking at the connection and when I held the connection the noise would go away, and when I let go, it would come back.

Did some resoldering and it seems to have fixed the issue. I always assumed that the noise was coming from the HM board, power supply, or the Thermocouple circuit. Never even thought about the Rpi connection. I mean the Pi worked fine, so I figured it was good to go.

So if you have noise issues and you can't figure it out, check your PI connection, and it can save what's left of your hair.
 

 

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