Turbocharged Rimatron 7MX

[Legaucho]

Turbocharged Rimatron 7MX

Hi Luc,

The location of C22 is correct in the original schematic diagram. If it was connected as you have shown then U6A would be disabled. Also, there is no problem with D1. The purpose of the U6A/D1 combination is to switch off Q1 in the presence of any discriminated target.

I have some questions:

1. How have you constructed the coil? The Rimatron uses a Double-D. The TX and RX coils are identical (9.5mH, 25 ohms) but the TX coil is centre-tapped.

2. How much of the detector do you have working so far? Try running it in All-Metal mode first.

Qiaozhi

Hi Qiaozhi,

thanks again for your help,
For the moment I don't built the DD coil, I have finish my PCB ( please take a look on the attached file to check it ). All seems working, the next step is the coil. I have some concentric coils but they don't have the characteristic needed.
The width of the circuit corresponds to the internal width of case HAMMOND ref. Manufacturer: 1455N2201.

[Qiaozhi]

Hi Qiaozhi,

thanks again for your help,
For the moment I don't built the DD coil, I have finish my PCB ( please take a look on the attached file to check it ). All seems working, the next step is the coil. I have some concentric coils but they don't have the characteristic needed.
The width of the circuit corresponds to the internal width of case HAMMOND ref. Manufacturer: 1455N2201.

Hi Luc,

Unfortunately I cannot read the .lay file. Please can you repost as a .jpg?

[Qiaozhi]

Hi Luc,

Forget my last request. I've downloaded the free viewer. Although it's looking for a bitmap file called "plan fond", it still loads ok.
I'll take a look and get back to you.

[Legaucho]

Turbocharged Rimatron 7MX

Hi Luc,

Forget my last request. I've downloaded the free viewer. Although it's looking for a bitmap file called "plan fond", it still loads ok.
I'll take a look and get back to you.

In case, please find the .jpg file of Rimatron PCB
Luc

[Legaucho]

Turbocharged Rimatron 7MX

Hi Luc,

Forget my last request. I've downloaded the free viewer. Although it's looking for a bitmap file called "plan fond", it still loads ok.
I'll take a look and get back to you.

In case, please find this file.gif
Best regards
Luc

[Qiaozhi]

Hi Luc,

I've looked at the PCB layout fairly thoroughly.
The only problem I can spot is that R2 is connected to pin2 instead of pin 3 of U2A. I think you may have commented on this earlier, but the original schematic is correct. It was a little difficult to trace out this design from the original PCB, as some of the tracks were obscured by the components. Many parts of the circuit had to rechecked using a continuity tester to confirm the correct wiring.

Good job!

To help with your testing:
The coil gave a residual reading of about 100mV pp. You should be able to improve on this figure by careful balancing, and therefore get better discrimination than the original.
TX amplitude was about 12V pp.
V+ was 5.16V, and GND sits 2.6V above SCR.
TX frequency was 3.48KHz.

[Legaucho]

Hi Luc,

I've looked at the PCB layout fairly thoroughly.
The only problem I can spot is that R2 is connected to pin2 instead of pin 3 of U2A. I think you may have commented on this earlier, but the original schematic is correct. It was a little difficult to trace out this design from the original PCB, as some of the tracks were obscured by the components. Many parts of the circuit had to rechecked using a continuity tester to confirm the correct wiring.

Good job!

To help with your testing:
The coil gave a residual reading of about 100mV pp. You should be able to improve on this figure by careful balancing, and therefore get better discrimination than the original.
TX amplitude was about 12V pp.
V+ was 5.16V, and GND sits 2.6V above SCR.
TX frequency was 3.48KHz.

Hi Qiaozhi,
Can you specify what you want to say about R2. its position on Pine 3 is it that really raised on the original card.
Thanks also for the testing informations.
Luc

[Qiaozhi]

Hi Qiaozhi,
Can you specify what you want to say about R2. its position on Pine 3 is it that really raised on the original card.
Thanks also for the testing informations.
Luc

I made a typing error in my last reply.
On your PCB, R2 is connected between U2C pin9 and GND, but it should be connected between U2A pin 2 and GND. That is the only mistake I could see.

[Qiaozhi]

I made a typing error in my last reply.
On your PCB, R2 is connected between U2C pin9 and GND, but it should be connected between U2A pin 2 and GND. That is the only mistake I could see.

I must get rid of this dyslexic keyboard.
This should have been: "but it should be connected between U2A pin 3 and GND".
U2A pin2 is NC (not connected).

Hope you haven't made any changes yet.

[Delbert grady]

funny

102nf capacitor ????? is there such a thing

[Qiaozhi]

102nf capacitor ????? is there such a thing

Oh yeh! Forgot to mention that...
C14 (102nF) and C27 (103nF) should both be 100nF.

This back-engineering lark is a real bugger!
Thanks for reminding me.

[Qiaozhi]

All seems working, the next step is the coil.

Hi Legaucho,

How is your project going?
Have you build the coil yet?

[Legaucho]

Turbocharged Rimatron 7MX

Hi Legaucho,

How is your project going?
Have you build the coil yet?

Hi Qiaozhi,
The PCB is finished, the components were assembled, and a first test was made but without result. I do not have an oscilloscope. I already built a TESORO Bandido uII max and also Hammerhead and these two circuits function perfectly.
I waits to receive the audio cable screened ( cable between coil and box ) to finish the head of detection. Is the resistance of each reel of 25 or 29 Ohms? Because I initially tested with a winding of 29 Ohms but I did not have a result. I reverified the circuit, the weldings as well as the connections as well as the values of the components, but it seems that something does not go. I saw that the C21 capacitor was to be connected to the SCR and not to the GND.
Can you take other photographs of the original on other angles of view. If you have some ideas, don't hesitate.
My best regards.Luc

[Qiaozhi]

Hi Qiaozhi,
The PCB is finished, the components were assembled, and a first test was made but without result. I do not have an oscilloscope. I already built a TESORO Bandido uII max and also Hammerhead and these two circuits function perfectly.
I waits to receive the audio cable screened ( cable between coil and box ) to finish the head of detection. Is the resistance of each reel of 25 or 29 Ohms? Because I initially tested with a winding of 29 Ohms but I did not have a result. I reverified the circuit, the weldings as well as the connections as well as the values of the components, but it seems that something does not go. I saw that the C21 capacitor was to be connected to the SCR and not to the GND.
Can you take other photographs of the original on other angles of view. If you have some ideas, don't hesitate.
My best regards.Luc

Hi Luc,

You are probably correct about C21. Looks like this needs to be connected to SCR, but connecting to GND shouldn't make a big difference. The RX and TX coils should both be 29 ohms. Note that the TX coil is center-tapped, so the two halves are each 14.5 ohms. The inductance is the important value, not the resistance, but you will need an inductance meter to test this. If you do not have an oscilloscope then you have a big problem. You were lucky with the Bandido and the Hammerhead, but this is unusual. Many others here end up using a big hammer and starting again.
If all else fails, then you can send me the PCB and I'll get it working free of charge. We are both in Europe, so the postage cost will be small.

Qiaozhi

[Legaucho]

Turbocharged Rimatron 7MX

Hi Luc,

You are probably correct about C21. Looks like this needs to be connected to SCR, but connecting to GND shouldn't make a big difference. The RX and TX coils should both be 29 ohms. Note that the TX coil is center-tapped, so the two halves are each 14.5 ohms. The inductance is the important value, not the resistance, but you will need an inductance meter to test this. If you do not have an oscilloscope then you have a big problem. You were lucky with the Bandido and the Hammerhead, but this is unusual. Many others here end up using a big hammer and starting again.
If all else fails, then you can send me the PCB and I'll get it working free of charge. We are both in Europe, so the postage cost will be small.

Qiaozhi

Hi Qiaozhi

Thank you for your proposition and information, I still will try to control the circuit and to realize the DD head of detection and to get an inductance meter. I must stop the tests in the next days because I must leave for a professional trip to South Korea. I have note your proposal for controlling my circuit, I keep your proposal but before coming to this possibility I would realize a second PCB because the first starts to suffer from the modifications and many weldings. Thank you again, I will keep you informed of the possible projections of my tests. With the best Luc