Full m/lab SD2000 schematics

[Geotech11]

Check if there is a frequency on the gate and drain of the mosfet transistor that enables the positive voltage of the 2n700 or that you put in, if the frequency exists it would mean that the mosfet is not working! There I also tried a bipolar transistor for example bc547 and I get 5v. The line that connects to the battery drop has nothing to do with the positive voltage! Maybe you have somewhere connected not to the mosfet that regulates 5v but to the line for voltage 5v? If something in the connection is faulty for example some component that is powered by the 5v line there will be no 5v voltage present at the output of the 2n7000 or whatever you are using at that location for that line or rail. I would remove the components from the pcb if you have a base and check the voltage, and if there is a voltage of 9.9v I would put back one component at a time and that way you can see which component is problematic or possibly there is a short circuit. Because of such problems that can occur when I solder components, I first solder the components that are in charge of powering the integrated circuits and only when I check and determine that there is normal power supply at the control points or lines, after that I solder the other components on the pcb.

Hello, thank you for your suggestions.
I have measured the 2N7000, and indeed, frequency signals are present on both its gate and drain. Could you give me a general idea of what might be causing the 2N7000 to malfunction? I measured the resistance across the +5V and -5V rails to be in the range of tens of kilohms, so there does not appear to be a short circuit. I have only soldered the components for the PULSE CCT, the SD2000 POWER SUPPLY AND REGULATOR CCT, and the LOW BAT CCT. In the PULSE CCT, the signal following the 10nF capacitor is a standard square wave; however, after passing through the 22k resistor, the waveform closely resembles a triangle wave. Is this normal?

[detectormods]

Put an isolated dc to dc converter module in It.

[Geotech11]

Check if there is a frequency on the gate and drain of the mosfet transistor that enables the positive voltage of the 2n700 or that you put in, if the frequency exists it would mean that the mosfet is not working! There I also tried a bipolar transistor for example bc547 and I get 5v. The line that connects to the battery drop has nothing to do with the positive voltage! Maybe you have somewhere connected not to the mosfet that regulates 5v but to the line for voltage 5v? If something in the connection is faulty for example some component that is powered by the 5v line there will be no 5v voltage present at the output of the 2n7000 or whatever you are using at that location for that line or rail. I would remove the components from the pcb if you have a base and check the voltage, and if there is a voltage of 9.9v I would put back one component at a time and that way you can see which component is problematic or possibly there is a short circuit. Because of such problems that can occur when I solder components, I first solder the components that are in charge of powering the integrated circuits and only when I check and determine that there is normal power supply at the control points or lines, after that I solder the other components on the pcb.

I'm not sure if it would violate any rules to upload a compressed archive directly here; however, I can package the design files, schematics, and PCB layouts into a compressed file and send them to you. May I ask for your contact details?

[Orbit]

Yes one way to determine that something in that part is to put as Detektormods said put an isolated dc on that line. Or remove the signal trace from the gate 2n7000 and connect it temporarily with the oscillator that you would have made from the 555 timer before that, set it to 62khz and it would give voltage, but the mosfet 2n7000 would heat up in the long run, but for the test it can!Try to replace 4093 or test 4011 and replace bs 170.. The best in this field Detektormods and the people who do the most work around Minelab devices!

[Geotech11]

Put an isolated dc to dc converter module in It.

Hello. Thank you for your suggestions.The gate of the 2N7000 is connected to Pin 4 of the CD4093. Measurements taken at this point indicated a signal of approximately 0.8V (at a frequency of 62 kHz)—a voltage insufficient to drive the 2N7000. Consequently, I proceeded to measure the signal at the CD4093's TP pin, where I measured a voltage of 6.2V (at 62 kHz). Subsequently, I connected the signal from the CD4093's TP pin directly to the gate of the 2N7000; at this point, the measured voltage rose significantly, indicating that components such as the 150µH inductor, the MOSFET, and the capacitor are all functioning correctly. Could you please identify which specific components are responsible for the excessively low output voltage at Pin 4 of the CD4093?

[Geotech11]

Yes one way to determine that something in that part is to put as Detektormods said put an isolated dc on that line. Or remove the signal trace from the gate 2n7000 and connect it temporarily with the oscillator that you would have made from the 555 timer before that, set it to 62khz and it would give voltage, but the mosfet 2n7000 would heat up in the long run, but for the test it can!Try to replace 4093 or test 4011 and replace bs 170.. The best in this field Detektormods and the people who do the most work around Minelab devices!

Hello. Thank you for your suggestions.The gate of the 2N7000 is connected to Pin 4 of the CD4093. Measurements taken at this point indicated a signal of approximately 0.8V (at a frequency of 62 kHz)—a voltage insufficient to drive the 2N7000. Consequently, I proceeded to measure the signal at the CD4093's TP pin, where I measured a voltage of 6.2V (at 62 kHz). Subsequently, I connected the signal from the CD4093's TP pin directly to the gate of the 2N7000; at this point, the measured voltage rose significantly, indicating that components such as the 150µH inductor, the MOSFET, and the capacitor are all functioning correctly. Could you please identify which specific components are responsible for the excessively low output voltage at Pin 4 of the CD4093?

[detectormods]

In every case of the +5 volts not being produced it always comes back to the 2n7000 failure. I’ve never seen any other fault as long as that 62 KHz signal is trying to drive it.

[N@SKO]

Hello. Thank you for your suggestions.The gate of the 2N7000 is connected to Pin 4 of the CD4093. Measurements taken at this point indicated a signal of approximately 0.8V (at a frequency of 62 kHz)—a voltage insufficient to drive the 2N7000. Consequently, I proceeded to measure the signal at the CD4093's TP pin, where I measured a voltage of 6.2V (at 62 kHz). Subsequently, I connected the signal from the CD4093's TP pin directly to the gate of the 2N7000; at this point, the measured voltage rose significantly, indicating that components such as the 150µH inductor, the MOSFET, and the capacitor are all functioning correctly. Could you please identify which specific components are responsible for the excessively low output voltage at Pin 4 of the CD4093?

CD4093 will not working ok!Must be MC14093 or HEF4093.They have more power output.I have same problem when building SD2000

[Orbit]

Detektormods, you are the most knowledgeable about the operation of Minelab devices, I would like to ask you to tell me whether and how many coils distance he gpx 3500 or 5000 gpx can detect a 3.5mm diabolo? And with which coil?

[Geotech11]

CD4093 will not working ok!Must be MC14093 or HEF4093.They have more power output.I have same problem when building SD2000

Hello! May I ask which manufacturer produced the HEF4093 you are using? Would the HEF4093BT,653, manufactured by Nexperia, be suitable for use?

[N@SKO]

I think will be ok.Datasheet says 10 ma output current.

[Geotech11]

I think will be ok.Datasheet says 10 ma output current.

Okay, since the +5V supply is missing, it is very likely caused by the CD4093. Thank you.