PI-2

[WesP]

Gary,
I have completed a PI-2 and am having some problems. I get 4.97 Volts at at TP1 and TP2. I have adjusted VR1 to get the required voltage at TP3. (I'm setting it at .75 Volts) This voltage doesn't stay constant but seems to slowly change. I have a good meter reading that is adjustable and a tone but the tone has a very unstable threshold and the meter bounces as the tone breaks in and out. I have checked for the correct polarity on all the caps and double checked the pins on the transistors for correct placement. I did note that the overlay pictures for the P1 and P2 show reversed positions for diodes D2 through D8. I changed them to match the the P1 overlay picture as my P1 is working well and they both use the same schematic. Would reversing the diodes have caused any damage to any of the components? I am not getting any reaction from the tone or meter when metal is moved close to the coil. Any sugestions on where and what to check. I have substitiuded the equalivent value resistors VR5, VR6 and VR7 while trouble shooting the board.

Thanks,
Wes P

[chemelec]

Gary,
I have completed a PI-2 and am having some problems. I get 4.97 Volts at at TP1 and TP2. I have adjusted VR1 to get the required voltage at TP3. (I'm setting it at .75 Volts) This voltage doesn't stay constant but seems to slowly change. I have a good meter reading that is adjustable and a tone but the tone has a very unstable threshold and the meter bounces as the tone breaks in and out. I have checked for the correct polarity on all the caps and double checked the pins on the transistors for correct placement. I did note that the overlay pictures for the P1 and P2 show reversed positions for diodes D2 through D8. I changed them to match the the P1 overlay picture as my P1 is working well and they both use the same schematic. Would reversing the diodes have caused any damage to any of the components? I am not getting any reaction from the tone or meter when metal is moved close to the coil. Any sugestions on where and what to check. I have substitiuded the equalivent value resistors VR5, VR6 and VR7 while trouble shooting the board.

Thanks,
Wes P

If you Email me directly, I can probably help better.
Always go to the SOURCE First for the best help.

However, First you need to check Both the +5 and -5 Supplies. If these voltages are within 1/4 of a volt from the 5 volt readings, they are OK.

Next, What voltage do you get for the -10 Volts. It should Read ABOUT 9.75 Volts.

Also DID YOU REMOVE ALL THE SOLDER FLUX from the Board.
"Failure do do this Can Result in the detector to Not Work, Or be Very Unstable".
This is Especially Important Around Q4.

The Exact Positions of D3 to D8 Isn't Critical. Either Picture is OK. They Just Create a .6 and 1.2 Volt Signal Limit for both + & - Signals.

Also, Depending on the Setting of R5A, R7A and R9A, and the Coil you have, This Detector May Also NOT WORK.
I Suggest Before Turning it On, Set These Timing Values as If it were a Pulse-1.

If you Substituted a Different Fet for Q3, Check the Pinout Connections to make sure its installed Correctly.

Gary