Problem with TGSL EDU

[knutdi]

Hi, this is my firs post, I have not found where they presented.

I have problems with my new TGSL, i have buy TGSL EDU in silverdog web with all components, and made the coil DD, the problem is that when move the detector sounds beep, when I touch any POT wire sounds beep, when touch some IC sounds beep, when approached my hand to GB POT sounds beep, however metals are detected correctly, I don’t know that do.
I use usb 2 cable, with this connections:

[knutdi]

I have made this coil:

[knutdi]

Look my videos with the problem:

http://www.youtube.com/watch?v=K0P2Bk49lMU

http://www.youtube.com/watch?v=xhdJuMxtPvw

http://www.youtube.com/watch?v=hGlBUTR6RJU

Sorry for my bad english, if anyone spanish can help me please contact.

[simonbaker]

Look my videos with the problem:

http://www.youtube.com/watch?v=K0P2Bk49lMU

http://www.youtube.com/watch?v=xhdJuMxtPvw

http://www.youtube.com/watch?v=hGlBUTR6RJU

Sorry for my bad english, if anyone spanish can help me please contact.

Please measure the oscillator frequency and the inductance of the RX coil. If possible, measure the capacitance of the capacitor in parallel with the RX coil (C6 .015 uF).

-SB

[knutdi]

Hello, how could I check the oscillator frequency? rx inductance I can not measure, I can only measure resistor is 23.6 ohm and capacitor RX is correct.

If I only connect the TX coil is the same problem, watch this video:

http://www.youtube.com/watch?v=po7yUFPBmyY

Thank you

[Qiaozhi]

Hello, how could I check the oscillator frequency? rx inductance I can not measure, I can only measure resistor is 23.6 ohm and capacitor RX is correct.

If I only connect the TX coil is the same problem, watch this video:

http://www.youtube.com/watch?v=po7yUFPBmyY

Thank you

Try removing the coax cable between the PCB and the coil. Then connect only the TX coil using a twisted pair of wires. It's possible the coax cable has become microphonic. Either that or you have a mistake somewhere and the gain is set too high.

[knutdi]

hi Qiaozhi, I tested with two different wires and the problem is the same, however I will try with a twisted pair of wires. where can i set the gain???
Thank you

[knutdi]

I tried to connect onlyTX coil with the twisted pair of wires, and the problem continues, when down the SENS POT, the problem down too, but then does not recognize the metals.

[Qiaozhi]

I tried to connect onlyTX coil with the twisted pair of wires, and the problem continues, when down the SENS POT, the problem down too, but then does not recognize the metals.

In that case, is the problem still present with the coil wires completely removed from the PCB? In other words, no coil connected at all.

[knutdi]

Whitout coil RX and TX conected, no sound present, no present the problem, but i think the coil are good. how can i tested this, I have not scope, only multimeter.

[simonbaker]

Whitout coil RX and TX conected, no sound present, no present the problem, but i think the coil are good. how can i tested this, I have not scope, only multimeter.

You won't get audio with the TX leads disconnected, so leave those connected.

When you disconnected the RX leads, at what point did you disconnect? Which end of cable?

I have had same problem with in the past and never found the exact problem.

Sometimes it is very difficult until you finish the MD -- pot the coils, mount everything solidly.

When you touch, you don't realize but the tiny vibrations, even moving air, can cause loose coils to chatter.

However, because you disconnect RX coil and still get problem, that seems different.

It is even possible that if you have strong EMI in your workshop, your body picks it up and couples it to the circuit. Try test outdoors, far from EMI.

Sometimes you just have to rebuild. But keep trying to test and isolate what source of the problem is.

-SB

[knutdi]

Hi simonbaker, the RX the TGSL disconnected from the motherboard, everything is solid mounted, have rejected an EMI source since I tried it on the outside and it is exactly the same, because I have no scope, I measured the impedance of the coils and is as follows:

RX 25.8 ohms --- 107 laps

TX 23.8 ohms --- 98 laps

I also measured on pin 4 of the LM393, where in theory there-5v and 6v I have, actually, it may be that the problem???

[compadre]

Hi Knutdi
Look here i had the same proplem hope this help

http://174.132.129.189/~moreland/for...t=17727&page=3

compadre

[knutdi]

Hi compadre, you write there " now everything is ok i only connect the shild wire to the conector to the coil "

Can you explain how you did it???

if I can put an image of how you did, i understand it better, my english is very bad.

[compadre]

Hi
do you use a metal box for your pcp?
take one wire where the shild is connect, and put it on the metal box (or on a Poti metal case) that is what i do and (no more touch proplems)