The probe end of the circuitry is fairly simple. The probe jacks are connected to the ATMega through the 100K resistor(s) of the RC filter that are located behind each probe jack (the resistors that are standing upright). That is the only component in the path between the probe jack and the ATMega. Additionally there is the capacitor of the RC filter that connects from the probe lead to gnd, and the pullup resistors (on the standard probes only) that connect from the probe lead to +3.3V. These are the 3 components in a row right behind each probe jack.
If your probes are not reading properly/steady you should inspect all of the soldering in these areas in addition to the solder work on the probe jacks themselves as well as the last 4 pins on the ATMega socket and touch-up as needed.
I used to run 732 probes and I never changed the resistors. I assume you are referring to older posts, because in the past the 732 probes were more problematic, would drop to OFF even at room temperature etc. But since the RC filters have been added to the probes (on HMV4.2) all of the probes register much better and do not drop off nearly as much (though I must admit I haven't connected a 732 recently to check). I use mainly Thermoworks Pro probes these days because I find them much higher quality/durability than the Maverick probes, but I haven't had a probe drop to OFF since I built the prototype HMv4.2.3 board, the RC filters do a very good job removing the noise that makes the probes drop off and/or fluctuate.
So, bottom line, focus on what is causing your problem, which is not the value of those resistors....
I cant tell if all that brown is burned board or charred flux all around the components in question, but there is a lot of it. You should once again clean that up with some rubbing alcohol and a brush so the solder joints are clean there without charred bits bridging from solder joint to solder joint.
If you want to remove the problem jack, you need to use solder wick to get all the solder off the pins. I know this sounds counterintuitive but if it is not wanting to wick well, add a small amount of solder right where the wick and iron touch and it will usually make it flow much better. Also make sure you clean the iron tip on a damp sponge just before (within seconds) you touch it to the wick.
I definitely need to be cleaning my iron more frequently and moving more quickly from sponge to joint. That was likely what contributed to some of my ugly dark connections. All in all, if I can get this up and running, I'll be pleased with my first attempt at soldering, regardless of how it looks.
On the probes you have working steadily... I would try them in boiling water (do NOT submerge the cable at all), if they land at 212 or really close to that I wouldn't worry about it. I know you have already seen the response curve of the probes with different resistors, you could change those resistors to tune the HM board to your probes better, but as someone already stated, the probes need to be accurate in the 100F and above range for measuring food temp and running the pit. If they are accurate above 100F then I wouldn't worry about it.
On the middle probe jack that you are still having a problem with. It is possible to melt those probe jacks when too much heat is applied, and also possible for solder to flow into the contact area, either way that probe jack is likely a goner. Your best bet would be to remove and replace that probe jack altogether. As for the best way to do that, you can wick away the solder or use your solder sucker to clear out the solder the best you can. From there heat one solder joint and rock the jack out of the board slightly on that pin. Then move to the next pin, repeat. Do this pin by pin until you can get the jack out of the board.
Finally, if/when you build an RDTC board the probes should read exactly the same. I run mine over a 50Ft CAT5 cable and often put the probe in the meat and plug it directly into the HM in my kitchen to see what temp the meat is at, when I move the meat to the grill and plug the food probe into the RDTC board the meat temp is always spot on.... So once you have the RDTC board you really dont need that food probe on the HM board. However, if when you plug a probe into RDTC on that problem port and it reads wrong there too, then you will have to fix up whatever problem you have on the HM board. Since they share the same circuitry from the probe jack (on the HM board) to the ATMega it is possible that the problem will persist after you connect the RDTC.
Sounds like you have something conducting between probe 1 and the pit probe then.... charred up flux perhaps? the probes should be isolated from one another, they all go into their own pin on the ATMega. The common thing between them is the 3.3V and the gnd.
Hmm, well, the powersupply goes like this....
~12VDC in from the wall wart
OKI takes in 12V and puts out 5V
the 3.3v regulator takes in 5V and puts out 3.3v
In the olden days the 3.3v regulator on the HM was optional when using a rPi, because the HM would feed +5V to the rPi and the rPi would return 3.3v to the HM, which runs the logic level stuff.
I just looked at the HMv4.2.4 schematic and I see 5V on the rPi header but no 3.3v. So it seems when the HMv4.2 is powered by the USB on the rPi, the rPi must be passing +5V to your HM and then the 3.3V regulator on the HM board is powering the HM logic level stuff...
So you should start out by powering the HM with the 12V wall wart, measure the 12VDC input across the power jack, then move over to your OKI regulator, pin 1 is the 12v input which should read the same as the power jack, pin 3 is the 5V output, the center pin is ground. You can ground your meter to the power jack gnd, then measure both outer pins of your OKI looking for 12V and 5V. You can also check for continuity from the gnd on the power plug to the center pin of the OKI....
I think you had some issue with the OKI and had to rig it up a bit if I recall properly? I would start investigations there... 'cause we know everything past the 3.3v regulator is working.
Nope, the blower runs on 12VDC so no 12VDC no blower..... and your not supposed to power the rPi and the HM board at the same time.... Too bad the OKI isnt flat, I have a bunch of them and would be glad to send you one for free but not sure how to post it to you cheaply?
Did you test the ground on the OKI board too? I recall that was the leg that was broken....