My GMC300 E plus was acting weird last coupe of weeks. Many times as of late, it would be reporting CPM and then it would flake out and report "0" for extended period of time, then it would go back to operating normal. So, logged a support incident with GQ Electronics and got a hold of an engineer who had me open unit up and adjust voltage going to the tube. I have a voltage meter, so for me this was relatively easy to do. There is a pot called R25 that is super tiny (needed a magnifying glass) and with very small eye glass screw driver he had me make adjustment to the POT and the GMC came back to life. How long it lasts at this point not sure.... but apparently the POT flaking out is a known issue at least with this model. Will keep you posted on how this pans on in the long run.

Best,

Paul

My 2+ month old GMC-320 started doing the same thing a couple weeks ago. I've power cycled it on a few occasions and within several hours it's back to 0 CPM. I haven't had a chance to call support.

Do you happen to remember the before and after voltage?

My GMC-200 has been outside in a ziplock bag (on an air purifier - South Beloit, Illinois) for over a year now while sending data to NETC using the Raspberry Pi with custom software from NETC.

Same here, my GMC200 has been outside as well for quite some time now, inside one of them solar radiation shields for temp/hum sensors. Been working great. Seems that there have been numerous issues with the newer models. I have (2) 200's and (1) 080 one and all 3 have been rock solid. I also have a 280 with the display and that one has gone nuts on me once in a while, just went ballistic clicking away like I was sitting on a dirty bomb or something until I shut it off and on again and was fine. But has done it a few times. The older ones without the displays listed above, no issue at all. Refuse to buy any more above the 200 model now.

Yes, the voltage was running at 1.1V. They engineer there said the R25 POT has intermittent problems. With a 10M ohm meter, reading is about 210V. So, slightly turning the pot cured my problem. The volt meter helps, but I suspect even if you don't have a volt meter, if you turn it slightly until the counter wakes up, you will be within an acceptable voltage range. Sorry for late reply.

Mine was in a ziplock back and survived the brutal Chicago cold winter. The 200 and the 300 Plus are different electronics and maybe the newer generation of POTs they used in manufacturing have/had a problem that did not exist in the 200 series. But like I said, it flaked out and I was on brink of sending it in until the support engineer at GQ provided me time saver tip.

Thank you for sharing the details of your research. It is greatly appreciated.