Surf 1.2 PI Help

[waltr]

IF when you removed U2 (NE5534) the output of U5 (78L05) now is +5V then either the NE5534 is bad OR you had it inserted backwards.
Recheck for where pin 1 of U2 is.

[Tatt2o]

thank you Waltr,
I changed the NE5534 but it was the same thing, hot U5, 2V output ... so I returned the NE5534 as you advised me and it was good. The U5 is no longer hot and I have 5V output.
As a problem never happens alone, I connected the coil that I made and I performed a metal detection test. But no sound comes out of the piezo. I measured all the resistors and they are ok. I checked the positive and negative voltages of the integrated circuits and they are ok. I wonder if it's not just from the coil. It has an inductance of 540mH (20cm diameter, insulated copper wire 0.5 and 34 turns). Does not having a sound can be related to this coil?
Thank you.

[kt315]

....

[waltr]

Did you Check the function of each Sub-circuit as you built with a DVM and an O'scope??
All clocks running?
Adjust each stage?

There is no way to troubleshoot from the output--- you must go stage by stage.

540uH sounds a bit high for a PI detector but should at least work.+
Did you adjust the value of R6 to get critical Damping?

[jladre]

MAKE NEW COIL. 260-350uH will work great.

[Tatt2o]

Hello everyone and foremost, happy new year 2018. I wish you health and success in your endeavors.
For my part, my first action is to finish my surfing PI 1.2.
I made a new coil of 20 cm diameter with 21 round of 0.5mm insulated copper wire. Still no sound. I am sending you the pin-by-pin voltages of all the integrated circuits below. Tell me if you notice an anomaly please.

U1 = NE555

1: 0v
2: 5.49v
3: 10.15v
4: 10.47v
5: 6.34v
6: 5.42v
7: 5.41v
8: 10.45v

U2 = NE5534 (for information I can adjust the value of pin 6 with the offset)

1: 3.11v
2: 0V
3: 0.02V
4: -4.66v
5: -0.76v
6: -0.14v
7: 4.99v
8: 3.02v

U3 = LM358

1: 1.87v
2: 0v
3: 0v
4 : -4.64v
5 : -0.22v
6 : -0.22v
7 : -0.28v
8 : 5v

U4 = 4093

1 : 4.99v
2 : 4.71v
3 : -4.37v
4 : -4.37v
5 : 4.99v
6 : 4.70v
7 : -4.55v
8 : 4.22v
9 : 4.99v
10 : -4.46v
11 : -3.67v
12 : 4.99v
13 : 3.68v
14 : 4.99v

U5 = 78L05

Input: 10.7v
Output : 5v
GND : 0v

U6 = 7660

1: 1.25v
2: 2.51v
3: 0v
4: -2.33v
5: -4.68v
6: 1.25v
7: 2.76v
8: 4.99v

U7 = 4066

1: 0v
2: -0.22v
3: 0v
4: -0.22v
5:-4.46v
6: -4.47v
7: -4.67v
8: -4.67v
9: -4.67v
10: 0v
11: 0.97v
12: -3.77v
13: -4.44v
14: 5v

Do you see anything abnormal?

Thank you.

[waltr]

None look abnormal but also a DVM can NOT reliably check that Clocks are working. As we all said use a O'scope to check clocks and pulses..
If the Pulses are not properly working then No audio.

However, you can TRY measuring with a DVM the output of each stage starting with the pre-amp U2 pin 6.
Look for a change in Voltage with a target near the coil.

[dbanner]

You need to start from beginning.
STEP 1: Remove all chips except 7660 or whichever one came with kit.
STEP 2: Make sure you have correct schematic without errors.
STEP 3: Download Electro Droid apk(free) from google play store and install on android phone. This app will help you to read resistor color code and capacitor code.
STEP4: Check and verify every single component on pcb is correctly placed and properly soldered. For this you need correct parts layout, dont just rely on silkscreen only. Also check for shorts and bad connections etc.
STEP5: Wind coil 22 turns 230mm Diameter coil with anything from .4mm to .6mm enamelled copper wire.
STEP6: Power on circuit and make sure you have correct supply voltages(+5v,-5v) approx.
STEP7: Disconnect battery and install all remaing chips paying attention to pin 1 placement is correct. Connect coil. Power on and check supply voltage correct etc. Adjust offset pin 6 on 5534 to 0v.

[dbanner]

If your detector is responding to metal when passed over coil then you can tinker with damping resistor value for optimal performance.

[Tatt2o]

Hello everyone,
I found another error, the C15 capacitor was reversed. I put it back in the right direction. New test and ...... still no sound. I have to revise all the resistances and everything seems ok.
Can you indicate to me points of tensions important to verify with the values that I must have?
Thank you

[Tatt2o]

Hello everybody,
I'did it !!! After having changed c12 I have changed all intégrated circuits. And.... It's all right. Thank you for all. See you soon.

[waltr]

Great it is now working.

[peyman 74]

hii

[qute1]

i am still "weighting" for the "stores" to get back to me about that Glass Hammer and 2 tins of tartan paint and as to the question of the Astable multivibrator............. not sure their response makes for polite viewing.

[Paraguayo]

thank you