Thermo probes skyrocket


 
T

Tony L-Iowa

TVWBB Fan
My probe temps go crazy just after I set an alarm enabled. I enabled probe 1 and 2 to change setpoint to 140 when they reach 190 temp. About a minute after this I got notifications that my probes exceeded 190 and I seen this.

http://imgur.com/22uoldS
http://imgur.com/yetE4GK

Thoughts? I am using the 60hz probe noise cancellation feature recently added.
 
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That's really odd. Are you able to replicate this, or did it only happen the one time? Any chance of coinciding events like a power surge or anything else?
 
So, things stabilized overnight but I had another even this morning as my wife left the home. I talked to my wife and she said this was when she closed the garage door. I had the HM plugged into my garage outlet. I've been having power issues on this worse than others. I thought the 60Hz "A/C input line noise filter" took care of things but this problem seems worse. I may need to figure out a way to get stable power that's non-outlet based unless another solution to this can be had. As I think about this more the garage door opening/closing may have been the cause of both events. This latest one don't seem to "fix itself". I may have to leave work and attend to this issue now...

IsXAxEP.jpg


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You could also look to completely isolate your HM and run it off a 12v car battery.
 
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I would definitely do some testing long term using a battery, to rule out your heatermeter and power supply.

Do you have any other issues with any other appliances in the house?
 
This is pretty bizarre, the fact that the two standard probes go crazy but track pretty closely to each other and the TC remains uneffected...
Maybe resolder the components in the path that delivers the 3.3VDC to the Pullup Resistors? If that voltage was flaky all the standard probes would get jacked up and would probably track pretty close to each other....
That would be Pin 7 on the ATMega and the resistors and caps around that area. The voltage jumps between the top and bottom of the board, you'd have to trace it out yourself if you want to check its exact path, but a shotgun reflow of solder joints in that area should do....
 
Perhaps it's due to the fact that the thermistor probes run directly into the atmega, but the TC probe runs through a dedicated powered amp and it's able to deal with the noise.
 
John Bostwick said:
I would definitely do some testing long term using a battery, to rule out your heatermeter and power supply.

Do you have any other issues with any other appliances in the house?
Click to expand...

I've tested with a DC battery pack before and the HM noise issues become non-existent. I don't notice other issues with any other appliances in the house. I do use a cheap $6 wall wart from Amazon.com for this heatermeter though. Anyone else have suggestions on a better quality power supply for these things? Maybe I'll need to find an old laptop computer supply and switch plugs on it.
 
No, the inductor just smooths some incoming noise which you'd see as the value jumping around +/- 1 or degrees. I don't know what would cause the value to just float away like that though, I've never seen it happen.
 
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