Building Wolf Treasure [Tesoro Lobo]

[Ruben2000]

This is my PCB, it agrees with the schematic I post. If there are any errors please let me know.

[MartyJ1963]

Hi Ruben,,,I hope you are having good luck with your Lobo project!
I noticed that there was a track not connected on the photo of your pcb.
Is this track supposed to be connected or not? Good luck, Regards, Marty.

[Ruben2000]

Thank you very much Marty for the detail !!
I apologize to everyone, on my PCB I had already corrected it but not in my files.
Here I post the WOLF LAY file on a single side and the black and white image in PDF.
To find out which is the last correct file, all you have to do is look at the date found on the PCB.

Thanks Marty you have a good eye !!!!

[MartyJ1963]

You're welcome Ruben. Good luck with your build. I may try to build the Lobo myself at a later date so I will follow your build. Regards, Marty.

[rolling rock]

According to what I see, only pins 2 and 3 of U11 are inverted from the diagram you published. The rest are fine, no matter the polarity, the important thing is the uvication of the pins. In my diagram only U12A the polarity of pins 2 and 3 are reversed but that has nothing to do with it. Any detail to improve the scheme will be welcome !!!

yeah but just remember that the schematic "(I) published" was originally posted by you, over on page one of this thread. I was just trying to clear up ambiguity where possible. I would be hesitant to trust the person who drew that schematic with a PCB layout, not before some judicious error checking.

[Ruben2000]

yeah but just remember that the schematic "(I) published" was originally posted by you, over on page one of this thread. I was just trying to clear up ambiguity where possible. I would be hesitant to trust the person who drew that schematic with a PCB layout, not before some judicious error checking.

Yes, I have had to correct the scheme, there are many schemes that have to be corrected, both the numbers of the pins and their polarities. But in the PCB that I published at the beginning everything is fine except for the detail that Marty gave me, but this last LAY that I published is all fine.

[MartyJ1963]

Hiya Ruben, How's the build going? Any progress yet? Regards, Marty

[Ruben2000]

Hiya Ruben, How's the build going? Any progress yet? Regards, Marty

Still nothing, friend Marty, there are many things I don't understand, it's hard for me to build Tesoro LOBO. I've tried to get it to work resonant at 17500Hz and non-resonant at 20Khz with no success. I have tried with several coils that I have built and nothing. If someone could help me or give me the steps to follow to find the faults at each stage, I would greatly appreciate it.

[MartyJ1963]

Hiya Ruben. Sorry to hear you are not having any success yet with your LOBO. I wish I had better knowledge of VLF Circuits so I could help you out. I'm still practising and learning VLF Circuits and Coils at the moment and still haven't learnt how to use my DSO 5102P Oscilloscope properly yet, Lol! I hope someone with the knowledge and experience of the LOBO sees your posts and offers you some help with it. It would be great when you finally get it up and running and this of course will help any others attempting to build the more advance detectors in the future. We're all here to help each other and learn this great hobby so I hope someone comes along soon with the information you're searching for. Good luck with your build and I hope you get it sorted. Regards, Marty.

[nalag46]

Hi everyone,
I have recently been asked to look at a Tesoro "Wolf Trax" that suddenly stopped working for not known reason. I have had a good amount of experience repairing many detectors of different brands, like Fisher, White, C-Scope etc, (all the good analogue circuits that are easy to see and work on) by this is my first Tesoro and having not been able to find a circuit diagram for this particular model, I was wondering if any of you knowledgeable good people would have one that you could pass on? I notice that this is an MDF to CMD design by Tesoro and is very similar to or appears to be an update from their "Lobo" model, but afer looking at your various copies of the "Lobo" diagram, I can see that most of the components used in the Wolf are different. Also, there is extensive us of SFM miniature analogue chips and other components that are clearly not use in the Lobo or other Tesoro models. So far, my initial test has consisted of checking the power supply and feed in. The 12v supply is being fed to the 8v Regulator and its output from there on it is not easy to follow without an schematic. I have checked all the electrolytic caps and they hold the full power supply but other than that there does not seem to be any signs of life from the speakers. I would be most obliged for any info anyone can supply. Cheers.

[dbanner]

Could this be lobo super traq? With microprocessor.

Assuming the micro is good, then obviously next is to check power supply for correct voltages. There is a negative rail, should be -6V or thereabouts. The power pins of each chip should have these voltages.

Then if no obvious clues as to where is the problem, oscilloscope becomes necessary to check waveforms at certain known points.

This circuit follows same typical block diagram of all tesoro designs, so finding tx oscillator and rx preamp output shouldn't be hard from tracing back the coil connection.

Then you look for the waveforms you're expecting to see, if they are present, then you go from stage to stage, through the phase shifters and demodulation.

Or maybe the speaker is bad, or the audio amp driving the speaker, you know, check the obvious things first.
Or maybe go directly to output pin(s) of micro, probing for any signs of life.

I don't know if there is schematic for lobo super traq.

[nalag46]

Thank you for all that. Unfortunately, my oscilloscope packed up a couple of weeks ago and I am still waiting for parts to get it back in working order (hopefully). So it is faultfinding with my trusted multi meter for now. All the obvious checks have been carried out for voltage feeds to the various semiconductors and that seems to be in order.
At the front of the board where the main +8 Voltage Regulator is, there is an 8pin CSRS 2951 chip, which I believe is a fixed voltage regulator at just over +5v. and this is the voltage that is present in all the ics. Also, just above these two, there is another 8 pin ic 2426C, kind of a voltage reference type but I do not know what is for and there is no voltage readings on its pins.
The peculiar part of this set up is a large analogue 18 pin IC mounted on a "socket" on the top left hand side of the board with a sticker on it and the writing NUG 5.2? No idea what this is and I assume it is fitted that way so that it can be replaced easily as it probably is prone to failure? However, the +5v from the regulator is present and there are various other lower readings from the different pins.
Because 80% of the components are SM types, which make them harder to fault find, the negative power supply from the batteries is fed directly to the center pin of the +8 V regulator which is soldered to the central strip on the underneath, and this rail does not connect to any other metal parts, like switches or even the coil's metal socket that is attached to the board. The speaker and the headphones socket have
also been checked and they are both working.
Like I said, it is a hard and arduos job without a circuit diagram, but I will persevere and see where it takes me.

[dbanner]

The 2426 chip you referenced could be a rail splitter chip. Texas Instruments has a datasheet. No voltages present is obviously bad news(or good news, because you found a problem). One of the pins is virtual ground, so I would think that measurements on other pins can be made with respect to this pin.

The 18 pin chip could be a pic16 micro.
The other surface mount 16 pin chip nearby could be a decoder/multiplexer.

[dbanner]

There appears to be a small switch next to the micro.

[nalag46]

Most obliged for all the info sent. You have got the exact circuit board I have so there must be quite a few of these "updated" models about.
Going back to my fault finding, the rail splitter ic2426 seems to be working withing the data tolerance, ie. the input voltage at pin 3 is 5v and the output on pin 5 is 2.48v (the same voltage is available on pin 5 also) I did not check it correctly the first time because I was measuring with the negative probe on a metal part of the board that is not connected to true -0v from the supply. The switch next to the micro has one side connected to ground negative pins 4 and 14 of the chip and the other side to pin 18 so by activating it, it just grounds pin 18 but I cannot tell whether this chip is faulty or not. It does have its input 5v voltage and there are other lower voltages at different pins too.
So happy days, I should carry on but I am running out of obvious parts to test as it all seems to be in quite a good nick, yet no a hint of sound from the speaker (it is alive though, as touching the pins of one of the two push-pull transistors nearby, one can hear a scratchy noise?).