Dead Heater Meter... I hate the rain...


 
R

RalphTrimble

TVWBB Diamond Member
I decided to leave my HM on last night to let the new ping pong valve work and try to gather some data for PID tuning. Would you know it we were hit with unexpected rain, when I woke up to dark skies I had a sinking feeling...

When I got out to the HM it was still on, display was on but I moved so fast to unplug it that I didnt notice if it had data on the display or not.

I took the case apart and dried out the parts, let it sit a while and then plugged her in, I'm getting black boxes on the display now and the fan is running all the time. Apparently the rPi survived cause I can connect to it via WiFi, but it can not establish serial connection with the HM...

In pulling the HM in and out of the case a couple times and drying it off etc the resonator ended up breaking off, will the unit power up without the resonator? For some damn reason I didn't order a spare when I ordered parts (putting in a spare parts order from Mouser today).

I pulled the processor from the board and am drying out underneath hopefully I can get her running again.

I think I recall you (Bryan) posting a pic that showed voltages to check on the HM to aid in troubleshooting? Any advice you can offer me to recover from this screw up would be greatly appreciated.

Thanks
 
hmpi-power.png


The fuses in the ATmega are set to "external resonator" so there's no booting it without it. You could reset the fuses but it would only run at 8MHz then which you wouldn't get any serial communication and the fan would be half frequency and the timing would be all slow, so I'm not sure that would be very helpful. Also linkmeterd will try to "help you" by reflashing it back to 16MHz every few seconds.
 
OK, thanks for the fast reply, glad the LinkMeter will try to help, I need all the help I can get! LOL

Actually that's really good news, cause I'm pretty sure the HM looked normal when I pulled the power (I think I would have noticed black boxes on the display) so it seems likely the broken resonator is the issue. I probably caused that problem myself while drying it off, but it came off really easily so it must have been bent around too many times already.

I've already cut away enough of the case on the resonator and soldered some wire in so I can reattach it to the board, gotta get the old legs out of the board first and then I will install it and cross my fingers...
 
It's ALIVE!

I'm glad to say she powered right up after I reattached the resonator... All seems well, display is right, it's reading temps right and the web interface is working just as it should.... Whew!

Is there a way for me to retrieve the graph from the overnight cook so I can at least get some data from the experiment?

I'm really happy to get it working again because I'm planning to try another pizza cook this weekend with a Maverick "High Heat" probe. I own two but managed to melt them both. One of them melted in the cable, I can feel the stiff section, the other melted with just the probe in the top vent, the cable feels fine so it must have been melted inside.

The one with the melted cable I was able to fix. I cut the cable before and after the melted part. Measured the resistance at the plug and found open circuit (when it was melted it showed nearly shorted), measured the resistance of the probe side and found it had jumped up to a couple hundred K (which is what a probe should read). So I reattached the cable to the probe and she works again.

I figure I can still use it, just inserting the probe only into the top vent. The reason the first probe melted while in the top vent was because I had no valve on the blower and temps raged out of control (over 700 degrees at the vent apparently). Now I am running the ping pong valve on the blower and so I think I will be able to keep the temps under control in the 600's for pizza cooking. I figure the probe was already dead once, why not give another whack at it... I'm still waiting for the 1000C thermistor from Vishay....
 
RalphTrimble said:
Is there a way for me to retrieve the graph from the overnight cook so I can at least get some data from the experiment?
Click to expand...
The data is only stored on the ramdisk because writing to the SD card every second would destroy the flash. In v9 it keeps a backup on flash that is restored when the power comes back but you're SOL in v8.

Glad to hear you got it working again. The ATmegas are pretty resilient and good up to 12V operating voltage so they tend to bounce back.
 
Yah, TBHWY I think if I had just let it sit and dry naturally it would have powered up without any problems. I took advantage of having it ripped apart and a hot soldering iron handy and finally mounted the LED's and thermistor so they reach the holes in the case. So at least I made some progress as result of the mistake...

Is v9 released yet? I'm still running the "Attitude Adjustment", although I haven't mixed one up to give it a try...
 
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The base firmware will remain the same, Attitude Adjustment. There's just some changes to the linkmeter package and a bugfix to the rrdtool package. I wanted to put more into v9 but because the printer has taken so much time there's just the database autobackup and the servo change so far. Not sure when I'll release it but relatively soon (a week at most).
 
Will the bug be fixed that causes the config to get screwed up if you hit SAVE when there have been no changes? That one gets me a lot, cause I tend to forget if I saved and then double save. I've gotten in the habit of making at least one minor change before I hit save every time so my config doesn't get screwed up....
 
Thanks for reminding me about that I thought I had done something related to it, but the changelog shows nothing. I'm finishing up the servo webui this morning so I'll see if I can reproduce and fix that too.
 
I could only find one problem with it, here's what I checked
-- Load config page. Try to press "Save & Apply". Nothing happens. WORKING
-- Reload config page. Change a single item. "Save & Apply". Wait for page refresh. Try to press "Save & Apply". Nothing happens. WORKING
-- Reload config page. Change a single item (and leave the field). Go back and change the item back to what it was. Try to press "Save & Apply". ERROR!

It tries to send the last configuration change you made before you changed it back. This is the only bug I could find and it doesn't really have the same gravity as you suggest. I've fixed this but if you can outline exactly the steps you take to have it totally hose your configuration, I'll look at it again. If not, this is v9-ready I think.
 
Well, I had brought this to your attention some time ago, and you were able to reproduce the problem at the time. If I hit "Save & Apply" on the config page when there have been no changes made things end up getting changed that I didn't want to. Like probe parameters change, or probes go to disabled, and the display settings change to 2-line instead of the 4-line I had selected.
 
Another Rain Victim

Left my HM outside, turned on Fri night and woke to unexpected rain on Saturday morning. It was working when I unplugged it and brought it inside but later in the day when I plugged it back in it had a garbled right side of the display and no network connectivity. Got the HM board working by cleaning it with contact cleaner and a toothbrush, but the RPi could not be brought back to life. Swapped in a spare RPi this morning and everything works again. From now on it does not go outside without a ziplock bag over it.

Bad things happen in 3's so watch out !
 
Sorry to hear your rPi didn't make it. I found water under the SD card so make sure you pull that and let it dry... Perhaps if you give it some time (and maybe try another SD card?) the rPi will come back to life? Glad to hear you had a spare... Watch out victim #3, rain is coming for you! LOL
 
Rob Trainer said:
Stick it in a bag of rice for a couple of days and see what happens.
Click to expand...

Paper bag??? I would think a plastic bag would just hold in moisture....

I have in the long ago past repaired arcade machines, we had a certain driver machine that had major circuit boards under the seat/foot board, when someone spilled a soda guess what happened? DRENCHED in soda. If I caught the boards quick enough, before the acid in the soda had a chance to eat at the board, I could remove the boards, wash them with windex and a toothbrush, rinse them with water and then DRY THEM THOROUGHLY before I powered them up (often times with the hand dryer in the bathroom) and the boards would come back to life most of the times...

EDIT: Somehow I missed the "of rice" in your post... That is a pretty good method too....
 
Rob - good idea, just submerged the rPi in Basmati.

The SD card is OK, it booted up the backup rPi, but I had already wiped the contacts with contact cleaner before trying it.

Should have taken the HM apart when it came it wet/damp, but since it was still working, figured that all would be OK. All this from .2" of rain. And now back to our regularly scheduled drought...
 
Yah, it wasn't much rain when it hit me either. I have gotten into the habit of setting a disposable tupperware container upside down over my HM when I walk away from it. It is not completely sealed, but it will keep the rain off, unless the wind is blowing pretty hard it should be safe under there...
 
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