Meat probes not working in a HM 4.3


 

Markus Haapala

New member
I've built four HM 4.3 versions, and in one of them, none of the meat probe connectors are working. It's not a probe problem, and it has been verified with a few Weber probes, which do work in the Pit connector.

What could be wrong?
 
All of the probes do not work? In that case I would make sure the pullup voltage and ground are getting over to the probes.
Here is the HM schematic, toward the middle you will see the 4 resistors connected to 3.3v and each probe, and next to it the ground for the probe jacks. Check for 3.3v at the top of those 4 resistors (R16-18 & R5)....

HeaterMeter433.png


...and of course make sure you have the probe type and preset set properly in the HM config.

PS Are the probes not working on the HM LCD and Web Interface, or do they register on the HM LCD and not the web page? If they do register on the LCD then you probably have a communication problem between the HM board and the rPi rather than a problem with the probe circuit
 
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There is 3.3 V at the top of the four resistors. Probe settings are correct in the web interface and the meat temps are not showing at the display either.

Is there a setting to set meat probes totally off?

It seems now that at least two out of four HMs are suffering from this. My own one, which I built first, is working fine. At least two built just a month later are not. The PBCs and parts are all the same.
 
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As you can see from the schematic the probe circuits are quite simple. They used to connect directly to the ATMEGA but a few versions back Bryan added the RC filters, they are made up of the resistor and capacitor that are in the circuit, then there are the pullup resistors, that's it, not much to go wrong.

If you have a lot of flux on the board left over from soldering you might try washing with isopropyl alcohol and a soft brush (let it dry before powering up!)

What type of probes do you have? There were some Maverick probes that have plugs which are too long and you cannot insert all the way in, you have to pull them back out of the jack a little bit to work.

In the HM config each probe has a "Probe Type" setting, which can be set to Disabled, Thermistor (standard probe), Thermocouple, or wireless probe. Set that to Thermistor. There is also a "Probe Coefficients" setting which you need to select to match your probe type.
 
I know those settings but I was thinking if there might be a major setting for all meat probes. Guess not then.

Two units have been tested now: one with iGill probes and the other with an Ikea probe. These are not in my possession anymore, that's why different probes. I know Ikea probes are crap but that's not the issue here. Both units behave the same way: any probe in the pit connector gives a value but any probe in any meat connector doesn't give anything.
 
There is no "major" or master setting for the probes, just the per probe setup you see in the config....
I don't see a preset in the HM config for Ikea probes? Do you have the probe type and preset set the same on all probes? (including the pit probe)
You said the probes you mentioned are not in your possession now, what probes are you using to test RIGHT NOW?
 
I meant that the HM units are not in my possession. The owners of them (my brother and another dude) are testing them and I'm reporting here.

Yes, probe settings are same for all ports when these people do tje testing.

In addition: not having ready settings for Ikea probe is not a problem in testing if the ports work at all. I tested my own (working) HM with an Ikea probe and it gave a temp value with any thermistor settings.

Are there any other points on the board to measure in order to diagnose this?
 
The probe jack connections go straight to the ATMEGA, only pass through one single resistor, not much to test here.... R22, R23, R28, R29. You can test continuity from the probe jack to the respective resistor and from the resistor to the ATMega pins(25-28). Make sure you have the capacitors in place (C15-18), that's all there is to the circuit besides the pullup resistors you looked at earlier.
I've seen people melt probe jacks during installation making them short out, other than the probes themselves that is all I can think of hardware wise relating to the probes....
An incomplete flash of the ATMega can make a HM do strange things, I guess that's a possibility. Maybe try to reflash them?
 
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For me, the receivers for the probes don't seem to be designed for the probe connectors. I have to pull them out slightly (about 1/8") from the socket before they register.
 
I mentioned that earlier, I know for sure one variety of Maverick probe has a plug that is too long and needs to be backed out to work, other types of probes may have similar issues as well. Some probes had grounding issues as well, would only work when the braid on the wire was grounded out, so using uncommon probes does put you in a questionable position.
I am a big fan of the Thermoworks Pro Series probes, ideally you would have one of them to test all of these ports to see if they work.
 
I do have Thermoworks probes but the problematis HM units are several hunderd kilometers away from here. :)

I have also iGrill, Ink-Bird and Ikea probes and all of them work in all connectors of my HM. The connectors in the problematic ones are 100% same model so there is no way this is a connection problem.
 
Well, I've named every component in the probe circuit(s), which are few, and every setting related to the probes... You indicated all are correct and assure me it is not bad/incompatible probes or odd fitting probes. Frankly I am at a loss, not a lot of ground to cover here and we've been over it all... Sorry I wasn't able to help... I still suggest your friends try some Thermoworks Pro probes....
 
Well, now you will laugh but remember that I don't have the problematic units and the people using and testing them are not familiar with HM.

The system does not work very well without the 100k resistors. :D Somehow I have installed the 100k resistor only for pit probe. When I got pictures of the PCBs I noticed this immediately.

I have suggested people buying Thermoworks probes (or the European ones under ETI brand).
 

 

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