I need help with idx pro silverdog red pcb!!

[chiuino]

Hi Guru's my idx pro not work but i have no idea where begin to control this circuit!!! I have only checked the + and - rails on the ic's and all seems ok, but no other check i have made. i did a 27DD coil with wire that i had in home... for tx 0.55 and rx 0.35. When i have turned on i heard a single beep and in range of 13cm far detect a cell phone. i Turned off and pull off all ic's.... i remounted ic's and from then on i did not have audio signal.
Where do I start checking?
Thanks to all those who want to help me!!!

This is my pcb

[CDI]

Rx wire should be max 0.20, ideal 0.15 - 0.18.
IDX is not machine which is tolerant on unbalanced coils...
How much milivolts u have on U1 pin 3?
Give more informations, coil inductances, voltages...

[chiuino]

For first...Thanks for help!
My doubt is that before worked but in a strange way and with little sensitivity, after i unmount and remount ic's i have no sound with the same coil and capacitors!!
My RX have approx. 30 mH for Tx approx. 0.600 mH
On pin3 i have 0mv and on pin6 190mv measured with circuit ground, instead with - from power supply i have 4.02V on both pin's
Thanks lot for your help!
Andrea.

I'm sorry!! I have checked u1 pin3 with ac set voltmeter and measured 200mv alternated current!

[kt315]

you need to read those threads from start.

http://www.geotech1.com/forums/showt...51-IDX-PRO-VDI
http://www.geotech1.com/forums/showt...-Modifications

[chiuino]

I'm not sure to modify silverdog pcb components before that all right working!
I have read for one night idx-pro-vdi thread but i don't found anything about where i can start for check this pcb!!
Can you give me some info about correct voltage value around the ic's pin's and transistor's??
Surely my coils are not nulled properly and poorly made, but why in first time the detector started with audible sound and recognize large object like cellphone?
I want to make it work......please
Thanks lot for help!!!
Andrea.

[kt315]

do you have an o-scope?

[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

[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.

[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

[sinclairuser]

is that lf347 the right wayround?.

[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

[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

[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]

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!

[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)