Magnum on steroids!

[nikko10]

swap the edge of the potentiometer output

[reiv]

Thank You for answer. But if i swap ("1" and "3") ground with -5v of the potentiometer i get no control volume at all. That is why I don't understand this.

[Qiaozhi]

Thank You for answer. But if i swap ("1" and "3") ground with -5v of the potentiometer i get no control volume at all. That is why I don't understand this.

I don't know this detector, but I've looked at the schematic.

Firstly I would check that the pot is actually connected between 0V and -5V, and that one end is not floating.
Secondly I would check that Q2 is a PNP transistor, and it is inserted correctly, bearing in mind that the same transistor can sometimes have different pinouts.
Also, try disconnecting the wire to the centre pin of the volume control (R26), and measure that the voltage at that pin can be adjusted from 0V to -5V. That will confirm the pot is OK.

[reiv]

Thank You Qiaozhi for Your good suggestions. Finally Solved-bad potentiometer, when I check it on multimeter it appers to be good in both ways.. maybe some bad connections inside. Wow it was hard battle. Thanks again and Regards

[zakari]

hi all
i gonna to make this detector
which pcb and lay out file is correct?
best regard
zakari

[reiv]

Nikko10 I have a question if You don`t mind. In this PCB ver.1 wich have You posted earlier there is more errors? Besides of BG, Volume pots and label 10nF ? I have major problem with discrimination- don`t work at all... All signals phase shifter works, but it don`t discriminate any metals.

[nikko10]

from "0" to the right and adjust the discrimination potentiometer

[reiv]

I know wich way to turn potentiometer, but the problem is discrimination don`t work even at "10" all metals has high tone. BG works fine ferrit is eliminated.

[nikko10]

there is also a trimmer for the tonality, maybe he removed the low tone altogether

[reiv]

I set this trimmer at the middle as You suggested at the other site (forum.cxem.net) In one tone mode discriminatoon don't work also. Coil was checked in other PCB and works fine

[Andre]

Dear Ivconic,

The value of R87 is missing.

[ivconic]

50k

[reiv]

Hi, please help me. I'm reaping of all my hairs beacuse of this circut. Maybe someone can answer how does it possible to not working discrimonation in one tone mode ?? If I switch to 2 tone mode all works fine, foil is discriminating if turnbthe nob etc. But in one tone mode beeps the same at any kind of metal, no reaction at disc. pot. I tried to switch 358, 393, 4053, zener and 4148. Even if I desolder 3v3 zener, 4148,1m5 behind comparator 393 it beebs at metal with no discr. I don't understand this circut.

[reiv]

Thanks to Vlaser, problem solved. If someone has similar sympthoms reason was - zener D1, she was new and checked her for short, but i guess not proper opens.

[Ruben2000]

Hello friends!!!
I would like to ask you a question.
I am assembling MAGNUM TH, could you confirm if I can use these replacements.
3FW=BC557
1GW=BC547
BL=BD139
AL=BD140


I would greatly appreciate your response.