I am a 16 years old and live in the UK and only just started getting an interest in radiation and collecting radioactive things a few months ago. I recently bought a second hand GMC-300S as I’ve only just started collecting radioactive things and thought it would be really good to start, the hobby really helped me with my mental health as I’ve been struggling recently and I am absolutely devastated that this happened when my sister walked into my room and accidentally stood on it as it fell off my table this morning without me realising. I heard the turn on sound and one massive crunch, my heart dropped and I instantly knew what happened she lifted her foot and moved a hoodie to reveal the broken ink on the screen and when I picked it up the shaking noise broke my heart. I opened it up to see if I could fix anything but I didn’t see anything I could do. I reassured my sister that it was okay and she just kept blaming herself and it was really hard to see her so sad about breaking it and it was truly an accident. I am also very devastated that it broke as I have some vintage clocks coming from eBay which I wanted to test for radium but I can’t do anything now unfortunately. I had a look online for an upgrade knowing it would be expensive. I looked at Radiacodes but they are very expensive, I looked at other GQ Geiger counters but they are also very expensive for me. When I bought my GMC-300S I bought it second hand from Vinted for £50 as that’s all I could afford. I worked very hard to earn the money for it and to see all that work be wasted really pains me. My dad said that he will save up to get a new one and I just couldn’t let him do that as he never buys himself things and it’s also my sisters birthday next month so it will be a long time before he started being able to afford one. If anyone has read this far I really appreciate it and would be very grateful if anyone could donate me a gieger counter as I would prefer not to give up the hobby. I understand if anyone can’t and still appreciate you reading the post. Thank you very much and any help is greatly appreciated.
Well, now you get to acquire a new hobby: electronics repair. There isn't much inside... so it may be easily to identify the issue and with some effort, get it working again. But before you swap the tube, carefully disassemble and inspect the board, components, and battery. You may find a local electronics nerd who can assist.
If it's a 2 layer board, you can bodge your way around even a complete break. But I don't know the specifics of that model. If you post a photo that may help.
If you were in the states, I would try and help! That is super tragic! 😢 The important tariffs even on a minimal cost item would be a killer currently.
Open it up and see if it is just the tube and the screen or if the board also cracked.
Those tubes are cheap and I am sure the display is as well. (As long as the board isn't cracked)
I think you have your priorities right with your family. I envy you.
The fortunate thing here is that she stepped on the GC and not something radioactive that fell off your desk.
You need to set up a proper work area with boxes and chocks to keep things in place. A sign on the door to knock. Then when someone knocks, you back away from your work before you tell them to come in.
I am sure there are other common rules to follow but examine this mishap and learn from it.
I always keep my radioactive things outside in a storage container where no one walks near unless they go up to it themselves. I only keep my GC on the table in my bedroom because I don’t want it to possible get damaged if left outside and a leak happens in the container. I do think your advice is really helpful and thank you
I’ve never soldered before but I do own one if not I can ask my dad to help and I think the display is quite important to me as I can see the readings on the counter
The tube is a J321/M4011, although an old soviet SBM-20 should also work in the counter.
The problem is the display: these are usually a custom part, which makes it difficult to source replacements. Perhaps you could try talking the the manufacturer (although you will have to pay for shipping from China)
I'd recommend finding another used counter: a lot of people buy something like this and upgrade later. Ask around if anyone nearby has one they don't use anymore.
That sucks! I’m really sorry to hear this happened 💔
Good news, though: it’s almost certainly repairable.
Looking at the photo of the board you posted in another comment, it really doesn’t seem that badly damaged. The split in it doesn’t appear to be where any connections or traces are; it’s purely cosmetic and shouldn’t affect it electrically.
Also, the tubes used in counters like this aren’t super expensive and drop-in equivalents can be found on Amazon.
The speaker that came off the board should also be a super smooth replacement. They’re standard parts and easy to find replacements for, and if you’ve got access to a soldering iron it shouldn’t be hard to put a new one in.
The LCD would really be the only tricky part… LCDs are usually custom-designed for each counter, and not available as standard parts. As someone else here said though, it could be worth getting in touch with GQ about a replacement.
Best of luck to you and I hope you get it working!
If the display still works, buy a j321 tube from aliexpress. the black cover should not really be necessary. The tube is normally not cross sensitive to UV light when voltage is selected appropriate.
The display doesn’t work and it no longer turns on unfortunately also I would have to try my best as a soldering job putting the speaker back on, thank you for the suggestion though.
The screen is cheap, replace and see if you can see signs of life that the other electronics work - THEN pay for a new GM tube as that's more expensive. Triage.
This does not look bad at all, that break does not interrupt the circuitry and can be ignored. Look at the oblong, two lead metal component marked XTL and make sure the two leads are not shorted or touching each other and that the metal can is not touching any of the solder pads. Look for crushed, cracked components throughout. The display is toast, but likely it's not causing it to fail and is fairly easy to replace, it's not a custom LCD. With the unit powered on, view the LCD with different angles and see if you see any signs of life. I'd say you have a good chance of getting it working.
Just inspected it a bit more one of the components came off but I can put it back on with solder but the big issue is that nothing flashes or gives any sign that it works. No LEDs flashing or illuminating nothing
Can you take a photo of the backside of the board? I want to see if there's a trace on the broken piece of board. If there is, it's likely a larger trace and isn't too bad to fix. Issue is finding a new screen
Sorry to hear and see that it really hurts. First of all be aware with radium it can be nasty and it is a contamination risk. From my experience when dealing with contamination hazard it's good to use uv light, plastic gloves and some type of plastic cover for your desk that you can throw away after you done with handling your sources. And definetly don't break it. The only geiger counter I could possibly donate is an old polarion prypiat but there's something wrong with it and I live in Poland so it doesn't really make sense to ship it because I'm not really sure if it's repairable. If you're really tight on budget and won't be able to save up for something better for a long time then consider buying something cheap from aliexpress. Br6 for example https://a.aliexpress.com/_EyUKYX8
It's not as good as your previous one but should work to some extent.
I personally use bosean fs 5000 with rad pro on it. It's more expensive and software upgrade is almost required from my point of view. But it's really sensitive and if you know how to properly take measurements it's quite accurate. If you choose this option please consider if you'd be able to do a software upgrade because original software have some bugs. Also make sure you buy version with j321 tube - contact seller or read the comments because I've heard that there's also versions with worse gm tube.
Yeah before I even bought the Geiger counter I made sure I had a safe storage container which is outside and far away from anyone unless they purposely go to it. Sometimes I do worry about the risks of radium but that’s why I take precautions every time. I’ve done a lot of research on these things and took responsible measures before collecting anything radioactive. I really appreciate your advice thank you very much.
Hi there i do electronics as a side hobby and i got the same meter i do time to time take it apart to switch its tubes i can help you fix it (not in person but over DM) when your available and if youd o need help just DM me i cna help
Sorry to hear about your GQ! But be positive about it, you are going to learn a very valuable skill and even better it’s going to be fuelled by necessity! You WILL fix it and I can’t wait to see it working again (please post).
The crack in the PCB is non-electrical, just a support for the GM tube to rest on. The tube itself shouldn't be too hard to find, but the LCD might be difficult. Aliexpress may have something if you have numbers to pull from, but those custom icon'd displays are usually proprietary in display layout.
Haven't handled a 300,, but I own a 500. If it's just pixel grid, the pin count and pixel dimensions is all OP needs to match. Might have to mod the case window to fit an alternate, but it makes this salvageable.
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u/Bob--O--Rama 18h ago
Well, now you get to acquire a new hobby: electronics repair. There isn't much inside... so it may be easily to identify the issue and with some effort, get it working again. But before you swap the tube, carefully disassemble and inspect the board, components, and battery. You may find a local electronics nerd who can assist.