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Lobo Exp

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Detector Prospector Magazine

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Everything posted by Lobo Exp

  1. Thing is with this model the board is most likely a multiple layer which makes it even harder to reverse trace the circuitry. The Russian clone model on Ebay is only a 2 layer, conductors on both sides and nothing in between with a laminated board. It's a big enough mess by itself and for sure this model is way beyond that. Is this a replacement board or was it removed by unsoldering the leads? It appears to be a new board with no solder in the J points, so there must be some instructions lit for it. If so, it would be a big help to Trisha providing her board isn't toast now. I would like to k
  2. For sure on that! A schematic would be a life saver. I could draw one up but it would take a fair bit of time to do it. I just don't have one to reverse engineer. Trouble is with the ST is what I have seen as at current here in the photo posted, they are SMD which makes it tougher to do. I have attempted to track down this info myself and spent a good amount of time to come up with NOTHING yet. Someone has to have this info but finding out who is the deal and it would probably require a subscription fee to access that info. I used to have that kind of access years ago when I was doing repair w
  3. Pots inside the housing on the board are for tuning the detectors frequency, discrim, rough ground balance, amplitude, and then there are the volume, fine ground balance, external discrim, sensitivity and threshold on the panel. The ST has a momentary push button on the handle a think for resetting the GB. I think it can be used in auto or manual GB by setting a switch on the panel too. If the photo posted of the circuit board is of a ST, I see 9 pots, and no one has a schematic of that detector or has found one and posted it that I know of, so I can't say exactly what each one does. The phot
  4. Ok I just came back to this post and from looking at the photo, which is kind of hard to go by, you basically have 3 colors of wire, Red, Black and White, I'm going to go out on a limb and state this, most of the Black wires are going to go to a ground point. If you look at the wires going to the dials, these are what are variable voltage dividers for adjusting the detector circuitry. Black wires should go to a ground, red wires are going to go to various points of the board that supply the positive side of the power in the circuitry. The white wires go to the circuit points that are classifi
  5. Yeah my bad, I see that now, I just went by it too fast for it to register and as I was reading and responding, that part of the post went away on my screen.
  6. I saw that, 4 or 5 pin arrangement. I finally found my way to MetalDetector.com yesterday evening and looked at what they have to offer and found several coils that are listed to work with Tesoro models compatible with each other. The prices are not too bad considering what they run for some other Detectors/brands. I don't have a problem with paying $150 give or take $50 for a piece if it's right and since I am not an experienced prospector, (yet) Haha, I only need to lay out the cash for just one coil to start with and make sure my project is even going to work. If and once I get to that poin
  7. I am looking someone that has extra or used coils that are still in decent condition. I am trying to build a detector from one of the Russian boards and will be needing a coil first for testing and later if the detector works, for hunting. It needs to be tuned to 17 to 18khz to work. The coils for Tejons, Vaquero and Cibola and maybe other Tesoro models will function. I don't know that much about the models Tesoro sold and there doesn't seem to be much info on the net about such details. Coils seem to be hard to find for these units also. I have been searching and not finding much. I found on
  8. Well that sounds like a possible cold solder connection. Most of the time when something stops after it warms up it is a component issue. But working when it warms up, I would look for a bad connection first. If the board is assembled with lead free solder, it is more brittle than the older 60/40 lead tin stuff and can fracture at the joints.
  9. If you can post a photo of the side of the board with the traces, may be both sides have traces. I can tell you for certain if the photo is clear enough. I have a board for the old classic in kit form from across the Atlantic I am working on. There should be a Voltage regulator for the board, it has 3 large flat leads, the center lead is the negative terminal, also tied to the heat sink, which should lead to a wide trace that boarders the PCB. The black wire goes to the center lead. The red wire will go to the trace that leads to the end of a diode(opposite end from the white band if the diode
  10. Kind of what I thought too. I understand the old lobo is not top of the line in technical advancement by current standards and have been trying to find out how well people think the Lobo (not the ST) works. I would like to find some boards for a more advanced detector to build. I haven't sold myself on one of the features of the ST, the auto discrim, but it has the option to choose auto or manual from what I have read. I would like to find some parts for some of the other models too, but haven't seen much. I'm of the opinion that the more dials and switches something has the better it works,
  11. I just read something today about the audio battery indicator which I am assuming is a feature of the older units, has been replaced with the little LED placed in the central area of the PCB such as on the Russian Fed PCB offered on Ebay. Since I never had any experience with any of these, I am anxious to get my board finished and tested. I do remember many years ago someone with a detector prospecting for coins and stuff in a local park. I was a still a young kid at the time,( like 40 or 50 years ago) it seems like the thing made so much noise I didn't understand how anyone could tell when t
  12. To Jeff Jones,,, I was wondering if you got rid of the controller you mentioned earlier? I have been working on one of those Russian Federation PCB's for a while now, a little here and there as I can get parts for it. I'm also looking for a coil that is tuned to the frequency this board is running at, 17,5khz. I may give a try at making my own coil, I have some enamel coated wire, but not sure if I have enough to make the coil. Making the form and getting the housing may turn out to be the hard part, getting the proper materials needed for it.
  13. I cannot say for positive on the issue of using a control box without the coil plugged, but I can say that with other circuits like 2 way radios, it is not a good idea to turn them on without the load coil which is what these machines are, transmitter/receivers. 2 way radios are meant to work with antennas tuned for a low standing wave ratio. Take CB's for instance, there are SWR meters for tuning the antenna length. Ideally you want a 1:1 SWR. Different frequency transmitters require different length antennas. Metal detectors work on the same principle. They send out a electromagnetic wave fr
  14. I forgot to mention a neat little piece of test gear that makes working with electronics much less hassle. The little GM328 transistor tester, which tests about every standard component one would work with. Transistors, MOSFET's, Capacitors, Resistors, Diodes, and Zeners up to 9 V, Inductors, and it identifies component leads and values. It will tell you what something is if you cannot identify it by the numbers or color code. Frankly I don't know how I got along without this device this long. It uses AVR C++ code running on a ATmega 328 controller with LCD display. The tester comes in kit or
  15. I ordered one of the DSO kits and assembled it. I haven't gotten it fully calibrated yet. There are some people that have posted Youtube videos about them and it seems replacing a few resistors in the circuit improves function and display for a cleaner wave pattern. I think I am going to order a second kit and assemble it with the suggested value which are 10x what the kit is supplied with. Also planning to order a kit form Function generator to work with setting up the scope and the detector. I also recently noticed that Digikey and possibly some other firms have done away with the minimum o
  16. Lobo Lover, you are discussing turning R33 and saying someone mentioned that moving it may be a bad idea. All of the pots which are on the board are supposed to be set with an Oscilloscope. if they get moved than the detector will be off frequency and likely not functional. I am still working on getting my board together, I recently purchased one of those kit form DSO scopes from Ebay and assembled it in hopes it will help me get my detector up and running. Also I got on this post a few months ago and it seems it has died? If anyone is still coming here, I would like to see what is happening a
  17. KAC made mention of getting parts through Digikey but the issue of getting parts not in minimum bulk, there is a Company in Calif.. Jameco Electronics and they will supply many parts in any quantity you need, the only requirement is to purchase more than $20 or so or they hit you with a sur charge. They have a nice web page. I purchased one of the blank boards some time back and started putting it together then set it aside. I have more parts on the way to go a little further with it. They should be coming in any time now as of Feb. 20/21.. From what I read some time back, the coil used with t
  18. At least now you know what and where to go if it happens again. May start thinking about getting a new pot. They are not all that robust anyway. A small metal wiper running on a thin layer of carbon inside a none sealed housing that gets dust in it. There are pots made that are better housed and won't be easy to get trash in them. Everyone usually goes for the cheapest piece available to get it working long enough to sell and after that, well you know. throw it away and get another, that's the American way.
  19. Coils are supposed to be shielded from the housing all the way to the coil. I would start by looking for a place or connection from the shield to ground point in the circuit to be a cause. These things are supposed to be super sensitive so it wouldn't take much of a leak in the ground circuit to let interference into the system. Beyond that, as I just noticed in your later post about the pots, yep, that would be about the same as a component value shifting, it happens. Glad you found the gremlin.
  20. Ok I just joined this site earlier today and I am having issues getting where I want to go. I think I may have hijacked someones post and if this gets where I want it to go, I appologise. I just read a new post by KAJ asking if the circuit could be modified to run at a much higher frequency. I would like to tell him that I believe it could be set to run about anywhere provided the correct components where installed on the circuit board to enable the 7555 to generate the desired freq. simply by replacing the resistors and capacitor with the values needed to adjust the timing of the IC.
  21. Just recently joined here myself and also recently acquired one of these boards. If you're still looking for help I can assemble board. I have a few ideas for bumping it up slightly and posted a somewhat long entry. Haven't seen it up here yet to see if it looks good, if it needs editing?
  22. I just recently got one of these Russian boards, which IMO looks like a good piece to work with. I read over the supplied build instructions which are fairly clear, but in a way are not totally, at the same time. I have worked with circuits quite a lot over several years, I went back to a site that discusses working with timer IC's of which in this build uses the 7555, a CMOS version of the vaunted 555 that uses 1/10th the power. This is where the MD transmitter freq. is produced. There are several ways to construct the oscillator and in the case of this design, I find one very small issue. Si
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