I need help with idx pro silverdog red pcb!!

[lamoiz]

Hello, check r39 .. 22k, the meaning of Q3 is it good? It is the power supply of your circuit? L impedance of the hp? I am not a specialist..but this is the first test to do. good luck .

[Wahyu]

Hi eduardo and Lamoiz

I have problem Q4 BC517, always getting Hot, with or without sound beep.

[lamoiz]

oupss.. 0.25 for rx coil ...
it s 0.8 for tx ..... sorry

[lamoiz]

Hello,
I have the same circuit of silverdog.
I also had a problem, but my fault ... I replaced the lm358 by a 4558 ... and so it does not work. J had manufactured a concentric coil but the operation is not good. Made a double d in 27 ... but after measurement, the tx made 1.5R for 550mh son 0.25 ... this work @ 6.70khz ..... and not 6.59 with 1uf it goes to 6.67 khz. My question to the gurus of the site is: is it a problem if the frequency is a little higher?
Moreover, I find that sensitivity is not very good.
Thank you all for your help .

[chiuino]

No eduardo my coils are umbalanced and for reach 6.5Khz i have mount 3 or 4 capacitors! but if you say this, i rewind a coils and perform measurement for exact mH and impedance....i have bought the exact size of wire that i read on forum 0.70 and 0.18 mm!!!
But if this is true why my detector at the beginning have ringed with some pieces of iron and with my cellphone?
Thx

This is the coil tx 0.5 and rx 0.35(too much big)

[eduardo1979]

Have you connected the 33nF and 1uF capacitors in parallel with the TX and RX coils?
Without those capacitors the detector will never work. In parallel with the TX coil, the 1uF capacitor is connected, and in parallel with the coil RX, the 33nF capacitor is connected.
It would be best if you put a picture of your coils, because the fault could be there.

[chiuino]

Only one thing can help me.....know in all ic's what kind of sinewave(amplitude etc. etc) and in amplifier where i should have voltage(how mV ...in which pin's)

[chiuino]

Hi eduardo1979 thank you for help!! but i have changed with another one and nothing ringing, and the terminals are in right positions because the serigraphy on the pcb is clear!! I'm very frustrated with this situation because i tried everything without results!

[eduardo1979]

You should check the MPSA13 audio transistor. It is possible that the transistor is damaged or that it is mounted in reverse. You should look carefully at the terminals E, B, C, that are correctly positioned.

[chiuino]

With my friend we have checked all sine wave in all ic's input and output but i do not have audio output with or without coils! Sine wave changing when object cross the coils and i think that is ok, also pots' working but i do not have sound from speaker.
Monday i reorder a pcb and some components from silverdog!! The pcb appear good but something was wrong with components or ic sockets or resistors!
Only one resistor is not the value that is in pcb 1.8k(r instead 1.6k that i have mounted around ne5534 but i do not think that this is the problem because all ic's oscillate right! Throw it all away and start again from zero.
I return to forum when it will arrive.
With a bit bitter taste.....Thanks to all for help!

Andrea

[chiuino]

Thanks yes it is in the right way!! Yesterday i have bought the right wire size and in the next few days i will winding the coils and return to forum with news!
Thank you bro!!

P.s. I have changed the speaker with another one 18 ohm impedance instead of 8 ohm

[sinclairuser]

is that lf347 the right wayround?.

[chiuino]

Sorry for delay!! Yes i have a pc oscope....better than nothing!
I have recheck with beeping all ic's pin's from top to bottom and all welds are ok!
In photo you see the little tin solder ball that i have removed but i think that not did do any short. You have hawk eyes Koala!
kt315...I have turned out coil and from circuit ground and pin 2 of u1 i have about 150 180 Hz fluctuant signal not 50Hz
This is what i view

[kt315]

Guess Koala he does have untuned coil. simple probe for any analog circuit - your hands.
turn out the coil. touch input of preamp. you have to see a passing of 50Hz signal.
that is WITHOUT ESPECIAL SINUS GENERATOR you do not want waste a money on.

[Koala]

Guess something went wrong with the reseat.


Try beeping each pin from the top of the component to the bottom track.

Something looks wrong here