MPP build stage 4 headphone test failed - seek advice

[Borisimo]

Thanks for your replies.

The coil is connected (coil is the white cables) and the yellow cable is being used as a jumper to connect the Rx and Tx pins. The photos in #5 of this thread might help show the coil more clearly.

I am asumming that one end of the coil cable goes to the Tx pin and the other end to the Tx pin. This is how I interpret the diagram in the MPP build document.

Cheers.

[Qiaozhi]

I am asumming that one end of the coil cable goes to the Tx pin and the other end to the Tx pin. This is how I interpret the diagram in the MPP build document.

Cheers.

Well ... that's why it's not working then. Have a closer look at the diagram (Figures 7 and 14 in the build document.
For a mono coil, pins 1 and 5 on the connector must be shorted together. The coil is connected between 1/5 and 3. The shield is also connected to pin 3.
Study the schematic and it will become clear that connecting the coil between pins 1 and 5 will not work. At the moment you basically don't have the TX driving the coil.

[Borisimo]

Oh Dear, I think I am making myself look even more stupid than I actually am....

So…..when I said 'I am assuming that one end of the coil cable goes to the Tx pin and the other end to the Tx pin'.

What I meant was, 'I am assuming that one end of the coil cable goes to the Tx pin and the other end to the Rx pin. (Where Tx pin = pin 2 on PL2, and Rx pin is pin 2 on PL4). Screen connects to pin 3 on PL2.

There is no connector as such….like on a five pin connector on a Tracker 4. My coil ends just connect into the PL socket connectors, as per the picture in the previous post.

So my understanding is that I have it connected as per figure 7 and 14 in the build document.

Once again, thanks for your reply.

[Qiaozhi]

Oh Dear, I think I am making myself look even more stupid than I actually am....

So…..when I said 'I am assuming that one end of the coil cable goes to the Tx pin and the other end to the Tx pin'.

What I meant was, 'I am assuming that one end of the coil cable goes to the Tx pin and the other end to the Rx pin. (Where Tx pin = pin 2 on PL2, and Rx pin is pin 2 on PL4). Screen connects to pin 3 on PL2.

There is no connector as such….like on a five pin connector on a Tracker 4. My coil ends just connect into the PL socket connectors, as per the picture in the previous post.

So my understanding is that I have it connected as per figure 7 and 14 in the build document.

Once again, thanks for your reply.

Connect the coil between pin 2 and pin 3 on the TX connector.
Then add a wire between pin2 on the TX connector and pin2 on the RX connector.
Connect the shield wire to pin 1 on the TX connector.

[Borisimo]

Thanks a lot for your reply.

I connected the coil as specified, but still have no headphone noise (for step 4).

So inspected the board, re-soldered any questionable joints and cleaned off any spatter and flux residue, but still no noise.

I do get a fly back signal shown in the picture.
Could I have damaged (fried) a component when soldering?

Thanks again for your replies.

B

[Borisimo]

.... forgot to mention that I tried this with a commercially made (Bounty Hunter) coil, and the results were very similar to what I get with my home made coil, so I don't think its the coil.

Cheers,

[Qiaozhi]

.... forgot to mention that I tried this with a commercially made (Bounty Hunter) coil, and the results were very similar to what I get with my home made coil, so I don't think its the coil.

Cheers,

The Bounty Hunter is a VLF detector, so the coil will not be suitable for a PI.

[Borisimo]

Ok...so that doesn't help

What information could I provide that would help anyone to understand the problem,

does it make sense that I'm getting a flyback signal (as per the picture), but no sound.

Thanks again.

[geoscash1]

Ok...so that doesn't help

What information could I provide that would help anyone to understand the problem,

does it make sense that I'm getting a flyback signal (as per the picture), but no sound.

Thanks again.

Take a close up pic of how you have wired the coil plug and the wiring to the PL2 and PL4.

As for sound, do you have the correct chips in U8/U9 and U10 and are they inserted correctly?

how to wire your mono coil

[Rinkerdink]

Thanks guys, just thought I'd let you know this thread has gotten me to the next stage of the build ��