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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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I have a small, handheld geiger counter made by a firm called RDX
Nuclear (model is DX-1). Unfortunately, a much younger family member than I decided to try putting a 9V battery in it, but he put it in the wrong way before I could intercept him. Now, when the activation button is pressed, all I'm getting is a constant tone. Within the tone, I can hear individual clicking as if it is still taking counts, but that's it. Also, the indication needle is pegged. Here is an image of the top of the circuit board: https://i.imgur.com/kSHzB0T.jpg Unfortunately, I've never seen a schematic of this unit on the web even though it seems to be sold all over the place. Contacting RDX, all they want to do is replace that tiny board... for $120. So, if you hooked it up backwards, what would you check first? I did check the diodes and they all seem fine. |
#2
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JB Haskins wrote:
================= I have a small, handheld geiger counter made by a firm called RDX Nuclear (model is DX-1). Unfortunately, a much younger family member than I decided to try putting a 9V battery in it, but he put it in the wrong way before I could intercept him. Now, when the activation button is pressed, all I'm getting is a constant tone. Within the tone, I can hear individual clicking as if it is still taking counts, but that's it. Also, the indication needle is pegged. Here is an image of the top of the circuit board: https://i.imgur.com/kSHzB0T.jpg Unfortunately, I've never seen a schematic of this unit on the web even though it seems to be sold all over the place. Contacting RDX, all they want to do is replace that tiny board... for $120. So, if you hooked it up backwards, what would you check first? I did check the diodes and they all seem fine. ** The CMOS IC is the most likely be damaged. ...... Phil |
#3
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On 2/15/21 4:54 PM, Phil Allison wrote:
JB Haskins wrote: ================= I have a small, handheld geiger counter made by a firm called RDX Nuclear (model is DX-1). Unfortunately, a much younger family member than I decided to try putting a 9V battery in it, but he put it in the wrong way before I could intercept him. Now, when the activation button is pressed, all I'm getting is a constant tone. Within the tone, I can hear individual clicking as if it is still taking counts, but that's it. Also, the indication needle is pegged. Here is an image of the top of the circuit board: https://i.imgur.com/kSHzB0T.jpg Unfortunately, I've never seen a schematic of this unit on the web even though it seems to be sold all over the place. Contacting RDX, all they want to do is replace that tiny board... for $120. So, if you hooked it up backwards, what would you check first? I did check the diodes and they all seem fine. ** The CMOS IC is the most likely be damaged. ..... Phil Thank you, that's what I have suspected as well. |
#4
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JB Haskins wrote:
https://i.imgur.com/kSHzB0T.jpg Unfortunately, I've never seen a schematic of this unit on the web even Given the seeming simplicity of that board in your image (it appears to be a single sided board) have you considered investing a moderate amount of time into reverse engineering a schematic by following which traces on the underside connect to which components from the top? |
#5
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On 16/02/2021 8:08 am, JB Haskins wrote:
I have a small, handheld geiger counter made by a firm called RDX Nuclear (model is DX-1).Â* Unfortunately, a much younger family member than I decided to try putting a 9V battery in it, but he put it in the wrong way before I could intercept him.Â* Now, when the activation button is pressed, all I'm getting is a constant tone.Â* Within the tone, I can hear individual clicking as if it is still taking counts, but that's it. Â*Also, the indication needle is pegged.Â* Here is an image of the top of the circuit board: Â*https://i.imgur.com/kSHzB0T.jpg Unfortunately, I've never seen a schematic of this unit on the web even though it seems to be sold all over the place.Â* Contacting RDX, all they want to do is replace that tiny board... for $120.Â* So, if you hooked it up backwards, what would you check first?Â* I did check the diodes and they all seem fine. **As Phil has stated, the 40106 is likely to be toast. For less than 10 Bucks and 20 minutes work, you could replace every semiconductor in the thing. -- Trevor Wilson www.rageaudio.com.au -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
#6
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On 2/15/21 5:52 PM, Rich wrote:
JB Haskins wrote: https://i.imgur.com/kSHzB0T.jpg Unfortunately, I've never seen a schematic of this unit on the web even Given the seeming simplicity of that board in your image (it appears to be a single sided board) have you considered investing a moderate amount of time into reverse engineering a schematic by following which traces on the underside connect to which components from the top? The last time I tried to do that, it turned out to be a disaster although what I tried it with was a little more complex. Still, I might give it a go with this one. I already ordered a replacement IC and the transistors on the board- all are common parts and not expensive. Actually ordered more than one of each since I own at least two of these geiger counters. |
#7
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On 2/15/21 6:47 PM, Trevor Wilson wrote:
On 16/02/2021 8:08 am, JB Haskins wrote: I have a small, handheld geiger counter made by a firm called RDX Nuclear (model is DX-1).Â* Unfortunately, a much younger family member than I decided to try putting a 9V battery in it, but he put it in the wrong way before I could intercept him.Â* Now, when the activation button is pressed, all I'm getting is a constant tone.Â* Within the tone, I can hear individual clicking as if it is still taking counts, but that's it. Â*Â*Also, the indication needle is pegged.Â* Here is an image of the top of the circuit board: Â*Â*https://i.imgur.com/kSHzB0T.jpg Unfortunately, I've never seen a schematic of this unit on the web even though it seems to be sold all over the place.Â* Contacting RDX, all they want to do is replace that tiny board... for $120.Â* So, if you hooked it up backwards, what would you check first?Â* I did check the diodes and they all seem fine. **As Phil has stated, the 40106 is likely to be toast. For less than 10 Bucks and 20 minutes work, you could replace every semiconductor in the thing. Quite true, even without a schematic, none of the parts are uncommon or costly so ordered the IC and all the transistors. I got seconds because I have at least one other of these units. |
#8
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On 2/15/21 6:50 PM, JB Haskins wrote:
On 2/15/21 6:47 PM, Trevor Wilson wrote: On 16/02/2021 8:08 am, JB Haskins wrote: I have a small, handheld geiger counter made by a firm called RDX Nuclear (model is DX-1).Â* Unfortunately, a much younger family member than I decided to try putting a 9V battery in it, but he put it in the wrong way before I could intercept him.Â* Now, when the activation button is pressed, all I'm getting is a constant tone.Â* Within the tone, I can hear individual clicking as if it is still taking counts, but that's it. Â*Â*Also, the indication needle is pegged.Â* Here is an image of the top of the circuit board: Â*Â*https://i.imgur.com/kSHzB0T.jpg Unfortunately, I've never seen a schematic of this unit on the web even though it seems to be sold all over the place.Â* Contacting RDX, all they want to do is replace that tiny board... for $120.Â* So, if you hooked it up backwards, what would you check first?Â* I did check the diodes and they all seem fine. **As Phil has stated, the 40106 is likely to be toast. For less than 10 Bucks and 20 minutes work, you could replace every semiconductor in the thing. Quite true, even without a schematic, none of the parts are uncommon or costly so ordered the IC and all the transistors.Â* I got seconds because I have at least one other of these units. And I just got done putting a socket in there for the IC in case any future accidents happen, the job should be simpler. |
#9
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JB Haskins wrote:
============== And I just got done putting a socket in there for the IC in case any future accidents happen, the job should be simpler. ** Install a 1 amp diode in reverse across the batt connection while you are at it. Only fools design such items with no reverse batt protection. ...... Phil |
#10
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On 2/15/21 7:04 PM, Phil Allison wrote:
JB Haskins wrote: ============== And I just got done putting a socket in there for the IC in case any future accidents happen, the job should be simpler. ** Install a 1 amp diode in reverse across the batt connection while you are at it. Only fools design such items with no reverse batt protection. Good idea, thanks, will do that. ..... Phil |
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