STEP 8 FAIL

[loopin3]

Hi all,
im building a MPP and i have a problem with step 8, in each step the measured value :

1. Voltage at pin 4 of U8 -4.74
2. Voltage at TP1 5.1
3. Frequeny of pulse 1.08Khz and pulse width 50us
4. Flyback voltage about 350V
5. on TP 3 i measure a difference of 100mv or more when object is near the coil
6. Sample dealy of 22us with pin1&2 shorted of pl3
7. i confirm the dc voltage change wit object near the coil

tp9 with the audio pot dosent swing from -5 to 5, remain stable
what i can check?

[Goaty]

Check your audio pot connections are correct. Pin2 on PL6 should be connected to the pot wiper and the voltage on this this should should vary between +5v and -5v as the pot shaft is rotated.
Measure with you multi-meter + probe on pin2 of PL6 and the - probe on TP10. If you get a variable voltage here test for a similar result with the + probe on pin2 of U9.

[loopin3]

On pin 2 of pl6 the voltage swing , with potrebbe, fronte 4.8 to -4.8, on the pin 2 of u9 fronte 120mv ti -120mv... Offline i connect the headphone i hear a persistent sound without variation with object near the coil..

[loopin3]

Sorry but i reply with phone and t9 correct in my language.. i measure on pin 2 of pl6 and the voltage swing from -4.8 to 4.8 and on pin2 of u2 swing from 120mv to -120mv.. when connect the headphone i everything hear a sound without change when the obcjet is near the coil...