| T O P I C R E V I E W |
| Plymer1 |
Posted - 08/11/2022 : 13:34:51
I just received a new GMC-500+ and have two questions:
1. It will often fail to detect anything. If I run a Factory Reset it will begin to work normally. I have had to do this 3 times so far today.
2. When I am getting a reading I have seen CPM go as high as 150. However the readings for mSv/h and µSv/h stay at 0. Shouldn't these also show something?
The 500+ is running firmware 2.40 and is running on default settings.
Can anyone help me understand what is going on? Thanks. |
| 33 L A T E S T R E P L I E S (Newest First) |
| Stargazer 40 |
Posted - 09/04/2022 : 03:49:29
The original tube in the slot (SI-3BG) and the new one (if a J707 has 1/16 the response of the M4011) are Survey GM tubes. As we've stated before, if you use as Survey meter for nuclear disaster, where only the less sensitive tube is in use, and you get a significant reading, then you would want to vacate the area as soon as possible. |
| Quaxo76 |
Posted - 09/03/2022 : 13:36:48
quote:
Originally posted by Plymer1
And the lower whatever it is gives no counts. Zero. Maybe a firmware problem?
Dunno, it’s going back today. Keeping the one with the actual tube because it works. Thanks for the help everyone.
I'm adding a comment here, even though some time has passed, because I have the same 2.40 version, with the new tube.
I remember being surprised by the lower tube's zero counts. But when I placed it near a really hot mineral specimen, it clicked a bit. I could get it to 2 cps max. I didn't write it down, but I remember that the sensistivity of the small tube was more or less 1/200 of the large one. |
| Stargazer 40 |
Posted - 09/02/2022 : 16:27:44
https://www.alibaba.com/product-detail/Geiger-Mueller-Tube-geiger-muller-tube_1600478526575.html
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| ullix |
Posted - 09/01/2022 : 23:01:49
@stargazer: interesting table. Could you please post the link to the source?
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| Stargazer 40 |
Posted - 09/01/2022 : 10:26:51
quote:
Originally posted by Damien68
it could be a j705 or j707 tube or something like that
Thanks for that. You can compare response to the M4011 on this chart.
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| Damien68 |
Posted - 08/23/2022 : 05:55:37
it could be a j705 or j707 tube or something like that
j705
https://fr.aliexpress.com/item/4000433616966.html
j707
https://fr.aliexpress.com/item/1005002406670196.html |
| ullix |
Posted - 08/22/2022 : 22:31:48
@EmfDev:
why this reluctance to give us clear information?
What is the tube's name, where is a specification sheet, what is the sensitivity, what is recommended anode voltage? |
| EmfDev |
Posted - 08/22/2022 : 10:39:47
the new GMtube 2 is similar to SI-3BG according to support. |
| Plymer1 |
Posted - 08/17/2022 : 04:51:28
Sorry all, it has already been returned. I do know both "tubes" were turned on, but can't test further.
It was either a faulty part or (I more suspect) faulty firmware.
Thanks for the help. |
| ullix |
Posted - 08/17/2022 : 00:05:43
quote:
EmfDev: What is the GM tube type that you replaced the SI-3BG tube with? (What's under that shrink wrap?)
Indeed, what is it? Or is it a trade secret?
And how is its sensitivity specified?
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| Stargazer 40 |
Posted - 08/15/2022 : 15:46:14
EmfDev: What is the GM tube type that you replaced the SI-3BG tube with? (What's under that shrink wrap?) |
| EmfDev |
Posted - 08/15/2022 : 11:09:07
Hi Plymer1, Can you turn on tube 1,2 CPM display under Main Menu -> Init Setup -> Tube Settings -> Tube1,2 CPM Display and measure the watch again?
Tube 2 has been changed for 2.40. |
| Stargazer 40 |
Posted - 08/15/2022 : 03:55:03
It'd be easier to simply check what Tube 2 voltage is set at than to go through actual measurement if not already packed up to go. |
| ullix |
Posted - 08/15/2022 : 03:08:21
quote:
And the lower whatever it is gives no counts. Zero. Maybe a firmware problem?
The firmware is supposedly allowing to switch on only tube#1, or only tube#2, or both.
Can you verify that both tubes are set to "On"?
Can you test for High-Voltage (~ 400V) at the pins of the whatever-it-is?
@Damien: you can't just put the "active part" of a Geiger tube under plastic and expect it to work. You do need the gas space with a certain gas composition around it.
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| Plymer1 |
Posted - 08/15/2022 : 02:14:18
And the lower whatever it is gives no counts. Zero. Maybe a firmware problem?
Dunno, it’s going back today. Keeping the one with the actual tube because it works. Thanks for the help everyone. |
| Damien68 |
Posted - 08/15/2022 : 00:02:04
the components to generate the high voltage for tube 2 are still present, so it must be a smaller GM tube.
certainly they placed only the active part of the tube on a PCB
 |
| ullix |
Posted - 08/14/2022 : 22:51:07
OMG, what on earth is that?
It reminds me of my recent review of PIN diode counters (https://sourceforge.net/projects/geigerlog/files/Articles/GeigerLog-Review%20PIN%20Diode%20Geiger%20Counters-v.1.0.pdf/download). They are as insensitive as the old 2nd tube, but then no counts will surprise nobody.
Or is Stargazer right in assuming an even smaller tube being what looks like the dead body under black shrink-wrap?
Is there still high voltage at the pins where the tube clamps had been, or is it now in the 3...5 V realm?
Give your Grandpa clock some workout: while recording CPM, CPS, CPM1st, CPS1st, CPM2nd, CPS2nd with GeigerLog at 1 sec cycle time, guide the clock with its radiating side very close along the big tube and the whatever-it-is thingy.
What counts do you get?
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| Stargazer 40 |
Posted - 08/14/2022 : 10:47:29
Yes, the boards appear to be the same. Both are new as of Sept 2020. The boards on my 500+ are version 5.2 from June of 2019 (corrected). The board still has the option for doubling the current to the first tube. Crystal X2 may be different in this later board (silver cylinder below largest chip). Wonder what else has been added or improved? Looks like the replacement low sensitivity GM tube is soldered in so can't replace easily. |
| Plymer1 |
Posted - 08/14/2022 : 10:22:45
quote:
Originally posted by Stargazer 40
Can you please post a picture of the new PC Board exactly like the old one. I'd like to compare the other components and the version of the board and date. The low sensitivity tube has been replaced. I would imagine if you cut off the shrink wrap (DO NOT DO THAT!) you'd see a much smaller GM tube of similar low sensitivity mounted on a tiny PCB board to fit the larger PCB board.
Sure thing. Looks the same to me.
 |
| Stargazer 40 |
Posted - 08/14/2022 : 10:13:00
Can you please post a picture of the new PC Board exactly like the old one. I'd like to compare the other components and the version of the board and date. The low sensitivity tube has been replaced. I would imagine if you cut off the shrink wrap (DO NOT DO THAT!) you'd see a much smaller GM tube of similar low sensitivity mounted on a tiny PCB board to fit the larger PCB board. |
| Plymer1 |
Posted - 08/14/2022 : 06:14:22
The clamps for the tubes are even missing. The board is raised to about mid tube height. Here's a side view.
 |
| Plymer1 |
Posted - 08/14/2022 : 06:08:02
quote:
If your counter looks differently, please, post a photo.
Wow, does it.
I opened both. The new one (re 2.29) looks just like other pictures I've seen on this board. Glass tube on bottom, completely normal. But the first one I got (re 2.40) is different. Instead of the glass tube, there's something soldered to the board. It seems the black shrink wrap is plastic - no idea what the black board is or what is on it.
 |
| ullix |
Posted - 08/13/2022 : 23:37:15
This flip-flopping between firmware versions 2.29 and 2.40 is strange!
The higher count of the clock may not mean anything. Very likely it is a strong beta emitter, and then the count rate very much depends on the precise positioning of clock and counter. However, a readout of 255 concerns me, because this is a byte value with all bits set, which is used in the firmware to indicate "missing or empty values". Could indicate yet other troubles.
To see what tubes you have you'll have to unscrew the backside. There are 2 tubes: a long one and a short one. Both are glass tubes. The long one is the main tube, the sensitive one, and may be blackened with some black paint, or a black paper wrapper to overcome light sensitivity. The short one is useless anyway, and should be clear glass. Best to switch it off in the menu.
If your counter looks differently, please, post a photo.
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| Plymer1 |
Posted - 08/13/2022 : 10:30:47
UPDATE:
Got the new counter just now. The new one is Firmware 2.29. It had 98% battery when turned on (the previous one stayed at 100% the entire time I used it). It immediately read background radiation (the previous never did). AND most importantly it has a lower, clear tube where the previous one had only something black and shiny!
Comparison pictures on Imgur at https://imgur.com/a/ALIrz9G
And as a side note, my Grandfather's watch (which previously read up to 130) now has a max reading of 255. Radium, grrs. |
| Plymer1 |
Posted - 08/12/2022 : 05:51:34
Stargazer 40 - It was purchased on Amazon. Just looked at the order and the seller was "GQ Electronics LLC". Pic of the version number below.
The +/5% is an option now, off by default. It is under User Option/Accuracy Display. Under User Options/Fast Estimate Time the choices change the %. The Options are Dynamic, 5, 10, 15, 20, 30, and 60.
And no, by "normally" I meant it gets a read in CPM. Others are still 0. Before reset, it doesn't get any reading at all in anything.
Ullix - have already set up the return (just pulled it out for a second to get Stargazer the above info). The new one should be here later today. Ifit has the same problems I'll install and hook up GL and let you know.
Both - I agree This whole thing reeks of a firmware issue. It works great after resetting, and the numbers (being relative) should show up unless there's a coding error. I will know later today when I receive the replacement.
Version Pic:
 |
| Stargazer 40 |
Posted - 08/12/2022 : 04:06:54
After the resets and it begins to work 'normally' I take that to mean you are seeing display of uSv/h that are in line with ullix's numbers when looking at watch, or is the data simply background number with uSv/h numbers displayed below? |
| Stargazer 40 |
Posted - 08/12/2022 : 03:52:56
Thanks for posting the pic. If you look at the post you referenced for the other Rev 2.40 you will see GQ's response (EmfDev) that 2.29 is the latest Rev. That was June. I just received that for my 500+'s last week.
If 2.40 is on currently sold units, and a jump from 2.2x to 2.4x number normally means something significant changed, this may mean there is a new PCB in the unit. Ullix asks the appropriate question in that this may be a Chinese version that GQ is now marketing in the US. The display is missing the +- 5% in the upper right corner of the CPM count window that shows in 2.29 version.
We need GQ to weigh in. Don't think this is hardware even if the Chinese version. Firmware seems to have a fault? |
| ullix |
Posted - 08/12/2022 : 03:51:27
The CPM=101 with the watch is quite possible. But after a factory reset this should equate to 101 CPM / 154 CPM/ (uSv/h) = 0.66 uSv/h.
Looks like a rather severe bug in firmware 2.40.
I'd be interested in seeing what info GeigerLog is giving? (After connecting GL to counter: menu: Device --> GMC Series --> Show Extended Info)
Edit: Chances are that the counts given by the clock are mostly due to betas. If so, then a uSv/h value is utterly meaningless, because the calibration was - supposedly- made with gamma, and is valid for gamma only!
The value of 0.00 would then actually be a proper value ;-))
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| Plymer1 |
Posted - 08/12/2022 : 02:56:02
Thanks, ullix.
As stated it was just a typo in the post. It’s the GMC-500+ as stated in the title. Bought from Amazon in the US. Using firmware 2.40
I guess I’ll return it as defective. Even after factory reset I just get the below readings (readings from my grandfather’s watch). Disappointing but I appreciate your help. Nice software btw, great work there.
 |
| ullix |
Posted - 08/12/2022 : 02:28:40
quote:
Do I need to post a picture for you?
Actually, this would be great, because the name "GMX-5000+" is unexpected. All the "experts" around here are baffled ;-)
And, if you can, a pic showing the inside would be even nicer!
Where did you buy this device? Can you give a link? Is that by any chance a Chinese product purchased in China?
But to your questions: Verify that your device is NOT light sensitive. Operate in complete darkness. I suggest to use my software GeigerLog to log via USB while having the device wrapped in box or anything light-tight. https://sourceforge.net/projects/geigerlog/
Of course, the readouts of CPM or uSv/h should be proportional. One at zero, but the other not, indicates a defect.
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| Plymer1 |
Posted - 08/12/2022 : 02:08:39
Also, here’s someone else who has the same firmware.
https://www.gqelectronicsllc.com/forum/topic.asp?TOPIC_ID=9910 |
| Plymer1 |
Posted - 08/12/2022 : 02:05:46
Why would I lie about this? I got to this in the About menu. Maybe I’m looking at the wrong thing but it said “re 2.40” - I assumed that was the firmware.
And yes, I mistyped the model number in the post, but I typed it correctly in the topic. I accidentally added a zero. Fixed it just for you.
Either way my two issues stand.
Do I need to post a picture for you? |
| Stargazer 40 |
Posted - 08/11/2022 : 17:45:37
Not sure if this is real post. Latest rev is 2.29, not 2.40, and the model is GM 500+. |
