Probe 2 Showing Temp


 
T

TommyE

TVWBB Member
Well almost got all my problems solved. Here's the last one. Probe 2 is showing a temp when nothing is plugged in. Here are a few pictures of my PCB. Any help would be greatly appreciated.


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Is the resistor actually connected to the spot where the arrow points to. Doesn't seem like it from the picture.

 
I was wondering the same thing I re soldered it from the bottom a few times to no avail. Should I try and solder it from the top?
 
Yeah, I'd try from the top. If there's not enough wire to make it to the hole, you can try and secure it to the metal back of the probe jack. Those 2 are connected together on the PCB.
 
I would wiggle the resistor leg with the soldering iron while soldering from the bottom, adding solder as you wiggle the resistor leg, making sure your get the resistor and the trace on the board hot... and make sure the board is sitting flat when you do this so gravity is pulling the solder down. You should be able to get solder to flow through the board doing it like that... Otherwise, it's a tight fit up top for a soldering iron, depending on which type you have I guess....
 
I tried both methods and was able to get a bit of solder on the top of the board and still no dice. Is this problem isolated to the food 2 area or could there be other spots to look?
 
What probe type and preset do you currently have set in the Web UI for Food 2?

This is the path from the Food 2 probe to the Atmega

 
Well I was able to solder the resister on top of the board and still the probe 2 is showing a temp when nothing is hooked up. I think I'm stumped on this one. I'll probably look at it tomorrow again with fresh eyes. I just can't seem to place where to problem is.
 
If you fully remove the 100K resistor, which is the one that you've been trying to resolder, that fully disconnects the probe2 circuit from the atmega. The 10k and 100k resistors as well as the 0.1u cap are inexpensive and relatively common components, should you need to replace them.
 
Thanks Steve after messing around with it just now i believe it is the 0.1u cap but I'm going to order all three and replace.
 
The 100K resistor and the .1uf cap on each probe make up the RC filter, which is not actually required for the probe to work (didn't exist on the HM prior to v4.2). If you remove the cap and short across the 100K resistor that probe should work, that is if either of those components are the problem... (which I doubt unless they were way overheated when you installed them)
 
I haven resoldered yet but I forgot to put the socket in first and soldered the atmega328 straight to the board I wondering if I damaged the chip from heat.

But yes you can still see some of the pad...
 
I'd also see if you're receiving any voltage on the food2 pin on the atmega, as well as check the resistance from gnd to the food2 pin.

 
TommyE said:
So I removed both resistors and the cap. Probe 2 is still showing a temp. Any idea where to check next?
Click to expand...

If you remove the pullup resistor the probe temp will float up, you need to have the 10K pullup resistor in place. The 100K resistor is the one your HM can live without, but if you just remove the 100K resistor that lifts the pullup resistor away from the ATMEGA, so same result as having no pullup resistor... You can remove the .1 cap and then SHORT OUT The 100K resistor, that removes the RC filter from the circuit and allows the pullup resistor and probe jack to remain connected.... Check the voltage on your ATMEGA pins for all four probes and compare the working to the non working...
 
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