New build - No power


 
I thought it miraculously healed itself over night, but alas, it did not. I was curious about seeing the path the 12V takes to get to the blower pin, so I plugged in the 12V and followed it to that pin on the cat5. That all checked out fine. Just as I got to the blower pin, the unit gave a faint buzz and the LCD came to life. The readings were all over the place at first until I realized that it seemed to be because I was holding the probe jack pins with my right hand. After setting it down, I plugged in my pit and food probes and they measured fine. I tested all of the 5V & 3.3V pins and they read exactly as they should. I unplugged the power and mated the Pi and the HM again. Same as last night. The OKI stopped putting out 5V and was back down to 2.2V. I then tried reflowing the connections on both sides of the OKI board to see if there was something happening there, but I couldn't make it work.

Ralph, I'll PM you my info, I'll pay you for the OKI + plus shipping, however you do it. Thanks guys!
 
Well, that's really odd... If I follow correctly you say you have good 5VDC when the rPi is not connected, but it drops off when it is? I would like to ask that you do that test again, remove the rPI, power the HM with 12V, measure your 12, 5 and 3.3.... If you get 5v without the rPi connected then it seems it is working.
I would be glad to give you the OKI for free, no need to pay for that, the shipping you can cover... But my concern at this point is that perhaps it is not defective after all, seeing that it seems to work without the rPi connected,
 
RalphTrimble said:
Well, that's really odd... If I follow correctly you say you have good 5VDC when the rPi is not connected, but it drops off when it is? I would like to ask that you do that test again, remove the rPI, power the HM with 12V, measure your 12, 5 and 3.3.... If you get 5v without the rPi connected then it seems it is working.
I would be glad to give you the OKI for free, no need to pay for that, the shipping you can cover... But my concern at this point is that perhaps it is not defective after all, seeing that it seems to work without the rPi connected,
Click to expand...

I only had good 5V for a brief time when the HM was not mated to the Pi. After the 5V kicked in, I unplugged power, then mated the HM to the Pi, plugged power back in and it was back to not getting 5V out of the OKI. I tried before my boiling test yesterday, and again this evening, and it was the same thing while both with and without the HM mated to the RPi. I'm pretty 99% sure it is the OKI since the top of the OKI board is getting 12V but not outputting 5V.
 
Ok, I am holding your replacement OKI board right here. I will take either take it to the USPO monday and ask them the cheapest way to send it to you, or if I can figure out the deal with sending stuff cheap via paypal I'll do that... The issue I see is it not at all flat, so it can't really go in an envelope, so it is gonna have to be in a box or one of those plastic shipping bags or something..
 
RalphTrimble said:
Ok, I am holding your replacement OKI board right here. I will take either take it to the USPO monday and ask them the cheapest way to send it to you, or if I can figure out the deal with sending stuff cheap via paypal I'll do that... The issue I see is it not at all flat, so it can't really go in an envelope, so it is gonna have to be in a box or one of those plastic shipping bags or something..
Click to expand...

I ship a lot because I am an eBay seller. If you keep the package under 13 oz. it can go First Class with 2-5 day delivery and the cost will be minimal. I use both the plastic bags (with item wrapped in bubble wrap) and the bubble envelopes and they both weigh next to nothing. The PayPal shipping is very straight forward use this link:

https://www.paypal.com/us/cgi-bin/webscr?cmd=_ship-now

It is very nice of you to provide that Ralph!
 
RalphTrimble said:
I've got some foam to protect the item, but dont have the plastic bags or bubble envelopes... Where would I get them cheap?
Click to expand...

I have been known to keep and reuse the bubble envelopes that I receive shipments in as long as they are in decent shape...that would be the cheapest :) I have seen them for sale individually but I can't recall where it was. If you bubble wrap it well just put it in a large envelope. The shipping label (if you use PayPal) will be half of a sheet of paper (5.5" X 8.5").
 
Good idea, I will look around to see if i have one of those bags that isnt too mangled and I can use that... Thanks for the hints...
 
RalphTrimble said:
They do make flux removal products/sprays for cleaning boards but you should be able to get it done with alcohol and a brush. I would be interested to see what your board looks like now after some cleaning, because the pics you posted had a lot of charred areas and it was hard to see what is really going on there. Perhaps cleaned up it would be easier to spot the solder bridge.

Here is a diagram that shows where various voltages are present on the board, pay particular attention to the RED +5V spots:

hm-424.png


My guess....

The LCD contrast pot (that blue box thing) has 5V on it, that part is soldered in on the other side of the board so the pins are completely surrounded by the ground plane there. The soldering looks sloppy so there's a good chance to short that 5V pin to ground right there. Clean up that solder joint by removing a bunch of that solder. Also, the LCD Backlight jumper has 5V on it, clean that up and verify it is isolated from the ground plane also. The diagram should give you a hint on where to look for the short. (ignore the 3 red circles, I guess they were left over from helping someone else)

As for cleaning things up... Do you have a solder sucker or a role of solder wick? You kinda need one or the other to do the cleanup work properly. The cheapest/easiest way to go would be solder wick...
Click to expand...

So, I have to smoke a boston butt tomorrow for lunch at work on Tuesday. I'm all prepared to do it the old fashioned way. However, while I wait for my new OKI, I am curious about powering the servo through the microUSB on the rPi. Would that work? I know I need 12V for the blower and wouldn't have it via the microUSB. However, would the micro USB deliver the 5V that I see connected to the servo on the above diagram? I'm unable to decipher if that COULD come from the micro USB.

For a low and slow on my grill, I don't think I would ever need the blower aside from startup. To this point, I've maintained 225 with a 1/4 to 1/2 inch crack on my top/bottom dampers. I do get a lot of wind around the corner of my house that always seems to spike my temps, so the servo will be nice to close off at that point.

Also, I replaced my middle probe and all is good there!
 
Dominick A said:
So, I have to smoke a boston butt tomorrow for lunch at work on Tuesday. I'm all prepared to do it the old fashioned way. However, while I wait for my new OKI, I am curious about powering the servo through the microUSB on the rPi. Would that work? I know I need 12V for the blower and wouldn't have it via the microUSB. However, would the micro USB deliver the 5V that I see connected to the servo on the above diagram? I'm unable to decipher if that COULD come from the micro USB.

For a low and slow on my grill, I don't think I would ever need the blower aside from startup. To this point, I've maintained 225 with a 1/4 to 1/2 inch crack on my top/bottom dampers. I do get a lot of wind around the corner of my house that always seems to spike my temps, so the servo will be nice to close off at that point.

Also, I replaced my middle probe and all is good there!
Click to expand...

From looking at the schematic http://capnbry.net/linkmeter/pcb/hm-4.2/HeaterMeterPi.png it sure looks like your servo would function fine assuming the power supply you are using can supply the needed amount of current. The servo uses both the +5V and +3.3V lines in order to function and those voltages will be present.
 
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yes, the servo should operate from the rPi power, if the power coming from the rPi is enough to move it... I never tested that myself. So if you wanted to run damper only mode you could possibly do that while powered only through the rPi.
 
Thanks @ Ralph & David!

If I can get the RDTC built tonight (no promises), I will certainly give it a shot and report back how it works during my cook. After all this with my build, maybe something new, but not entirely useful will arise ;)
 
I did get it yesterday, thanks! I meant to let you know, sorry. I haven't gotten back to complete my RDTC build though.

I was pushing hard to get it done by the end of this past weekend because I had a work potluck this past Tuesday where I was slated for pulled pork. Since it was go time, I had to pause on the HM build and cook it the 'ole fashion way. I threw the meat on at noon on Monday and it was done about 9:30am Tuesday. Got it to the office, let it rest until lunch time & pulled it at my desk, which was fun :) My pit temps held well overnight, but I was still anxious. I had alarms on my Maverick set on the high end at 250 and on the low end at 205 and only had a one alarm at 250 at roughly 3am, but it quickly settled back down. I didn't even get out of bed.

I should be able to finish the rest of my build this weekend and report back.
 
Updating this topic to say the new OKI did the trick, although I lost the trace on the 5V pin. I was able to add 2 jumpers and all appears to now be powered correctly. I am having some noise on the TC probe, I'm looking at the noisy probe thread and may have a question there.
 
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