TESORO GOLDEN SABRE

[metaldetector107]

last TGSL

Hi Ivco SB Max Qiaohz and all
i have repaired the PCB abit now is better but bliv me it wasnt like that
just due to too many times of soldering and disoldering became like that
and it is home made PCB any way
here are some measurements if you can help me please
U106 pins
1 6v
2 0v
3 0.6v
4 5.20v
5 0.20v
6 0.03v
7 4.8v
8 7.9v
U107 pins
1 6v
2 7.3v
3 7.3v
4 5.25v
5 4.8v
6 0.09v
7 1v
8 11.20

thanks all

[simonbaker]

Hi Ivco SB Max Qiaohz and all

i have repaired the PCB abit now is better but bliv me it wasnt like that
just due to too many times of soldering and disoldering became like that
and it is home made PCB any way
here are some measurements if you can help me please
U106 pins

1 6v -- should be same as pin 7.
2 0v - should be same as pin 6, close enough.
3 0.6v -- too high! Should be near zero.
4 5.20v -- this should be negative 5.20, right?
5 0.20v -- too high! Should be near zero.
6 0.03v - should be same as pin 6, close enough.
7 4.8v - should be same as pin 1
8 7.9v - good.

U107 pins
1 6v
2 7.3v
3 7.3v
4 5.25v
5 4.8v
6 0.09v
7 1v
8 11.20

thanks all

Thanks, that is very helpful.

I see possible problems.

Let's check again with your oscilloscope.
(Also be careful about pin numbers so we are not making a mistake.)

Let's start with U106 (LM393) pin 1 (u106a output) and pin 7 (u106b output).

They should be the same according to schematic! But maybe fluctuating so you cannot measure well -- use scope and check.


Ok, now U106 pin 3 and 5.

U106 pin 3 (+ input) and pin 5 (other + input) should be a very small voltage that fluctuates around zero volts, when not detecting target.

I recommend using your oscilloscope and put sweep speed very slow, like .1 second per cm (so dot moves slowly across screen).

Put the voltage sensitivity around 50 mV / cm. Make sure you ground the probe and adjust the trace to zero volts first.

The dot should stay within about 40 mV of zero - the less the better (less noisy).

You said pin 3 was .6 volts -- much too high! Something wrong there. I repeat, should be +- 40 mV or less.

You said pin 5 was .2 volts -- also too high! Something wrong like pin 3.

-----------------------------------------

Ok, now I look at PCB. I admire that you drew by hand, did not use Ivconic's layout file. But so many traces are very very close to touching -- scary. You will have to work hard to save this board.

I circled areas where traces should be separate but look too close, you should check. You need to use ohm meter and make sure those traces are separate - scrape with tool if necessary.

There is one blue circle with green arrows pointing to it -- looks like important mistake, please check carefully -- it looks like traces are connected where jumper crosses over.

Anyway, that is some ideas to begin with.

Cheers,

-SB

[ivconic]

Good thing is that you moved jumpers on top side. Now bottom layer looks a bit better. Yet i would like if you check again these spots.
Red circles means that you check from shorts and blue means that you check from breaks. So use some sharp knife and additionally cut and clean Cu traces and flux on red circles and use soldering iron and solder again on blue circles...

[ivconic]

It would be much more easier to make new pcb and do all the job again. More easier than to troubleshoot this one. But this time you dont draw it by free hand or yes you can draw it manually but use ruler and thinner marker. Or you may print it on laser printer on thermo foil and after apply it on clean (cleaned with smalles sanding paper and washed with resin good) pcb by heathing to 150 degrees celsius with iron. Use some steel roller and roll over heated pcb and thermo foil so to good apply laser powder on pcb surface. Than gently remove thermo foil and if neccessary correct some traces with marker again.... this is best amateur method to do pcb.
Here are pics...i tried to spot any mistake looking at your photos...but my eyes are tired. Maybe someone else could spot mistake..

[ivconic]

Ok..i have some measurements here. No need to be exactly as i noted, but must be in ranges.

U106 pins
1 6v..............6V !?!? It must be from -6V to -2.1V
2 0v..............4.7mV to 5.2mV
3 0.6v
4 5.20v...........!?!? must be -6.xx V
5 0.20v
6 0.03v..............4.7mV to 5.2mV
7 4.8v...............!?!? It must be from -6V to -2.1V
8 7.9v..............OK!
U107 pins
1 6v
2 7.3v
3 7.3v
4 5.25v...........must be -6.xx V
5 4.8v............!?!?! It must be from -5.5 to -2.3V
6 0.09v
7 1v..............!?!?! It must be -5.5v and falls to 0V
8 11.20...........? Certain drop here....should be 12v least.. or you are using bad battery..



So.... it is obvious - you have a problem here..

Most probably you have break on negative supply rail somewhere on pcb. Use method to follow minus rail from chopper output to U106 and U107 pins 4.

It is like i guessed in one of previous posts - you have problems with negative voltage, that's why you get constant audio...

[Max]

Hi Ivco SB Max Qiaohz and all
i have repaired the PCB abit now is better but bliv me it wasnt like that
just due to too many times of soldering and disoldering became like that
and it is home made PCB any way
here are some measurements if you can help me please
U106 pins
1 6v
2 0v
3 0.6v
4 5.20v
5 0.20v
6 0.03v
7 4.8v
8 7.9v
U107 pins
1 6v
2 7.3v
3 7.3v
4 5.25v
5 4.8v
6 0.09v
7 1v
8 11.20

thanks all

Hi,
there's another easy way to make good quality boards (at least acceptable quality for these things like tgs) and that's similar to free-hand drawing... :

it's dry-transfers method

You buy dry-transfers in e.g. office shops... the ones that provide e.g. services and products for engineers... , in such places (in my place there are still many, but think in most of the world it's the same) you could find electronic patterns too... as well as other stuff like letters and numbers etc.

You'll be interested more in e.g. tracks and pads: there are various sizes... 1, 2, 3 mm wide and shapes... and for ics too, transistors... whatever

Once you get what you need you simply polish very well the new board and apply transfers making some pressure (rotating movement) with a pencil... and voilla... it will place over copper (there's glue on the back side of transfers) and stay there... that's for pads. For tracks you'll cut them with a blade and all fine...

It took more time than simple hand-draw but you'll get fairly better (and nice to see also) tracks and pads... also it will give you strong copper tracks/pads... cause sometimes the pencil you use for handdraw leave too few varnish... and etching will remove too copper from there... then you have to repair later...

here a picture of what I mean.

Kind regards,
Max

[metaldetector107]

thanks Ivco Max SB Qiaohz

Dear all
thanks for you all but let me say Ivconic you are briliant i have found the problem what was the problem Yes Ivconic i admit you are very very good
look the problem was exactly as you said from negative route i have checked the chopper step by step tel i found that the -lead of C4 was not connected to the route
thanks all again and i hope you as you are for futuer needs

best regards

[metaldetector107]

Last TGSL

Dear Ivco
now please tell me the best way to connect Dis switch and Sens, Discr Potanmeter i mean thier type of wire
and thier ground connection i know you metioned earler that shield wire fron cassette Head is good but
how to join thier shield to ground at one point do i need to cover shield as well to prevent any saturation please ..
another help about cable.
1- is it possible to use PC monitor cable
2- till now i could npt find exactly 100K for discrimination most of them around 80 to 90K
3- or to seprate coax cable which double shielded for RF made in germany i got it from BMW CD changer
4- which socket is good for cable connection
RS232?
VGA?
USB?

thanks so much

[ivconic]

Dear Ivco

now please tell me the best way to connect Dis switch and Sens, Discr Potanmeter i mean thier type of wire
and thier ground connection i know you metioned earler that shield wire fron cassette Head is good but
how to join thier shield to ground at one point do i need to cover shield as well to prevent any saturation please ..
another help about cable.
1- is it possible to use PC monitor cable
2- till now i could npt find exactly 100K for discrimination most of them around 80 to 90K
3- or to seprate coax cable which double shielded for RF made in germany i got it from BMW CD changer
4- which socket is good for cable connection
RS232?
VGA?
USB?

thanks so much

Actually...you dont need to do that. You may use ordinary pvc coated wires. But yes; it is better to use coaxials. From what you named there i 'll rather use VGA cable. Strip it and you will find 3 separate coaxials inside. Use those. On pots side use only "hot" wires and shield leave short but not connected. On other side all shields connect (find most suitable way to you) togather and that joint connect to pcb GND. Of course; "hot" wires on other side do connect on proper places on pcb.
This i suggest only for Disc pot. All/Disc switch you may connect with ordinary pvc coated wires...do not bug yourself to solder coaxials there - no need. Also Sense....no need for coaxials. Use ordinary wires.
About pots values....ha,ha,ha! Same case with me - brand new potentiometers oftenly have different resistances...not exactly 100K but pretty oftenly 80k, 85k, 93k....etc..etc.. Dont worry, use what you have there. Just make sure those are accurate - not to old and "expired".
Sockets...? What sockets? At pcb? I do not use sockets..i am soldering wires directly to pcb. Best way!
If you get to much instabillity despite good shielding and proper enclosure...than...hmm...you will have to reconsider your coil. Maybe coil is not balanced (nulled) well.
Ok..that was all. After you finish with packing and adjusting, let us know about detector behavior and performances..
Cheers!

[metaldetector107]

last TGSL

Dear Ivco
thanks for all your help i realy appriciate.
i have tested without shielding coils
i can reject most types of iron the black thingy ferrite 7cm long 1cm dia
only i hear carck 2.4cm coin at around 20cm
so do i need to shield the coil ???
thanks in advance

[ivconic]

You better do that. Apply shield on both coils.
2.4cm coin on 20cm is not such good result. 2.4cm coin it must detect least at 30cm, if not a bit more. But this is not cose of a shield. Either coils are not balanced properly, either you missmached wire gauge, coil dimensions or number of windings. Involve some effort and try to make good coil, shielded also.
Regards

[metaldetector107]

last TGSL

Dear Ivco
please u said your last tgsl will detect 1coin at 46cm in air if coil proper nulled can i get this resault if i try ????
may i use alaminum shaft because its light and stiff?

thanks

[ivconic]

Yes it is true. But that result was with monostabile mod included. Without monostabile mod , best you can expect with 27cm DD coil should be 1e coin at 30cm up to 34cm in air (Disc on "3", Sense at "10") very stabille , no falses, cable from coil to detector can be moved, touched, punched - not even one false signal.
I made over 30 coils so far. Let's say only 5-6 of those were so good to detect 1e at 34-36cm in explained conditions. Rest of coils were pretty solid in performances and usually do detect 1e coin at 30-31cm in air in same conditions.
If you are interested how TGSL works with monostabile mod than watch this video:

http://www.youtube.com/watch?v=CxUOcCQBqU4

This specific coil detected 1e coin at 41cm in air. A bit larger silver coin (2cm) detected at 48cm in air.
But....there is always some catch! Monostabile mod is not working very good on soil - tends to produce ocassional false signals, so i do not recommend it to you...at least not for now.

Al shaft ...bar.. ok, of course you may use. Leave 20cm plastic bar from coil and than use Al pipe to detector...As on any other original model.

[metaldetector107]

last TGSL

Dear Ivco
thanks so much, i have reduced coil inductance from 6.5mh to 6.2mh for RX and from 6mh to 5.8 for TX onw detection depth is better it is around 25cm for single 1.7cm silver coin..
monostable? do you mean Max mono the one with 555 trimer if yes
should i disconnect the main audio amplifier to connect monostable?

many many thanks

[ivconic]

No...i do not suggest you that. Do more experiments on coil. Try to improve it.