HeaterMeter V3 Got Wet ...

I am in need of some help from the forum. I've used my HM 3.0 for many a successful smoke. Until one smoke about 3 weeks ago. I had everything set up to go, and the HM in a zip lock bag to keep it dry. Well it started to rain. I got up, fired up my BGE, and plugged in my HM. Unfortunately, it had gotten quite humid inside the bag and water had condensed on the board. It worked intermittently, and then stopped working. I put it in a bag of rice to let it dry out. And I tried to fire it up again.

The Raspberry Pi turns on and the power LED is on. I get the red & yellow LEDs on the HM board to come on. But it never seems to boot up or do anything. Nothing on the display.

If I unhook the RPi, and plug in the power, the LED lights up with solid blocks, but doesnt do much more (and probably shouldnt).

I am trying to figure out how I salvage my controller. Is there a way to diagnose if my issues lie in the Raspberry Pi or the HM 3.0 board? If I need to replace one or the other, or replace some components on the HM board, I'll do that. Just looking for some help in trying to diagnose my problems.

Help! Thanks in advance!

Matt

I'm trying to remember back if I built a v3.0, don't think so.

After an incident like this I usually try reseating things. Remove the rPI, pull out the SD Card, make sure there is no moisture remaining in those areas. Remove the ATMega from the socket, make sure it's dry too, maybe warm it up a bit with a hair dryer while apart if you have doubts. Then re-assemble and cross fingers! You could also try reading the SD Card on a computer to make sure things are still ok there with the file system.

I know older HM's had a different power scheme. The 12V came in from power brick, the OKI DC/DC board regulates it to create 5VDC, then the 5VDC was sent to the rPi and finally the rPi sent 3.3v back to the HM to power the logic end of things. There was an optional 3.3v regulator on the HM board that you could install so the HM would function on its own without the rPi connected. (not SURE this is the way V3 was setup, but v4 was that way)

I would start by testing power, 12V in at the jack, 12V on the input leg of the OKI and 5V on the output. Then see if you have the 3.3v regulator installed on your HM board or not, if present check for input of 5V and output of 3V. If not present then you must connect the rPi and measure the 5V (output to the rPi) and the 3.3V (returning to the HM board from the rPi) on the rPi header. I think those voltages should be labeled on the board, or at least they are in modern HM versions

On the rPi, you can boot that up with an LCD connected to the HDMI port to see what is going on there. You can do that with the rPi on its own, powered by the USB port, or connected to and powered by the HM. Doing this could give you some idea what is working and what went bad.

I just moved, and am recommitted to getting my controoler fixed. I actually have a 4.0. Can someone help give me a diagnostic recommendation to start out? How do I determine if its the Raspberry Pi vs. the Heatermeter board? And if it's the HM board, are there some points I should probe to try to isolate the issue?

Any help you could provide would be fantastic! Thanks in advance.

Matt

Diagnosing the RasPi should be simple. Remove it from the HM board, power it up via USB, connect it to a screen via HDMI and see what happens.

To test the board, Ralph has provided some good info in the previous post, starting at the OKI regulator, where the power comes in and then start moving down the line.

Here are links to the schematic and PCB for the HM 4.0

Steve_M said:

Diagnosing the RasPi should be simple. Remove it from the HM board, power it up via USB, connect it to a screen via HDMI and see what happens.

To test the board, Ralph has provided some good info in the previous post, starting at the OKI regulator, where the power comes in and then start moving down the line.

Here are links to the schematic and PCB for the HM 4.0

Click to expand...

I was able to test the board. 12V in. 5V present at the output connector to the RPi. No 3.3V regulator or leg present. So I'm assuming things look good on the HeaterMeter Board.

When I try to boot up the RPi separately, I get the power LED to come on, but never any activity. I did find the SD card corrupted, so I formatted and reimaged and tried again. Nothing. I get nothing to output to the HDMI. Activity LED never lights up. Never initiates cat5 network connection. I then tried the RPi connected to the HM board, and i get the same thing. I'm assuming I have a bad RPi.

I'm going to order a new RPi. When I searched in Amazon, I saw this come up but it has 4X USB. I"m guessing this wont work (interference).

http://www.amazon.com/exec/obidos/ASIN/B01CD5VC92/tvwb-20

Assuming I need this one--can you confirm?

http://www.amazon.com/exec/obidos/ASIN/B008PT4GGC/tvwb-20

Hoping to get it back working soon!

Thanks for all of the help.

Matt

Yes, you want the original rPi model B, not the Pi3 Model B.

Being an older HM hardware version the power flow is a bit different, the HM uses the OKI to regulate the 12V input voltage down to 5VDC (which you have verified) then it sends the 5V to the rPi. The rPi regulates the 5V down to 3.3v and sends it back to the HM board, which is what the ATMega and most everything besides the blower runs on. So it seems like you have a dead 3.3v regulator on your rPi. You could confirm that if you like by looking at the rPi header pinout on the HMv3 schematic, find the pin where the rPi puts 3.3v out to the HM and measure voltage on that pin It would be best to do this with the HM board disconnected from the rPi so there is no possibility that the HM board is shorting the 3.3v out....

...but since you say the rPi is dead even when disconnected from the HM board my guess the 3.3v regulator on it is gone. My only concern with replacing the rPi would be if there is something on the HM board that is shorted out that could take out the new rPi when you plug it in. Unlikely though, I would guess either the rPi died from the water and most likely since the HM dried out if there was a short there it is gone now.

I do believe there was an option to install a 3.3v regulator on the HM board to generate the power for the ATMega, you could install that and the HM board should boot and work on its own without the rPi. You probably want the rPi functions so no real need to do this, except if you install the regulator on the HM board and it works that will verify the HM board isn't gonna kill the new rPi when you plug it in.

PS If you are adventurous it shouldn't be too hard to test track down the 3.3v regulator on the rPi board, measure the 5V input and the 3.3v output. If the output is dead you could try replacing the 3.3v regulator on the rPi, that might bring it and the HM back to life. It's gonna be a SMD component, but using a magnifier and a thin tipped soldering iron it's doable. During my initial torture test of the RDTC board, which has a SMD 3.3v regulator on it, I got the board wet and the 3.3v regulator popped. Replacing it got the board back up without damage to anything else. Another episode with water and it popped again, replacing worked again to fix the board. So as it turns out, if the RDTC board gets soaked and shorted out the 3.3v regulator will pop almost like a fuse and prevent damage to the main HM board.