Surf Pi diy - help??

[lmrubin]

Trying to build a Surf Pi 1.2....not an engineer...I had 2 different surf pi boards working, only to kill them after attaching cable and coils...I just finished another brand new board I'm embarrassed to say... I can't get this one to make a sound though (the buzzer is good). I feel like I'm banging my head against the wall...I've checked and rechecked soldering, replaced half the parts on the board etc. Power is definitely going in, and all the ICs show the negative and positive approximate 5v values.

I'm wondering if anyone has any experience building one of these, or if there's a particular forum where I might ask for some help...? Thanks in advance...

[waltr]

Do you have an O'scope???
Very handy for troubleshooting.

Use it to check all the timing circuits, TX pulse and RX sampling pulses.

Read the many posts on Surf PI and the other simple PI detectors about what to look for to troubleshoot.

[lmrubin]

Thanks. No oscilloscope, however I think I figured out the problem. It's almost too embarrassing to write it, but in case some other noob comes along and reads this thread...

I looked at my soldering and didn't see any pads touching. Everything looked ok physically. I checked the values of all the transistors and I started replacing parts. The batteries were fully charged. Anyway, after pulling my hair out, I took out my magnifying lense to scrutinize...I actually did this a couple of times, and resoldered a lot of what was there, hoping that maybe somewhere the solder wasn't making full contact. To make a very short story even longer...I saw a little whitish/bluish colored stuff, which I saw a few times before, and thought it was just residue from cleaning or from soldering and resoldering. On closer inspection, I noticed that there was actually a break in the trace - it was really hard to see, and I doubt I would have ever seen it with my eyes. I added a little copper tape, and after wasting hours and hours...beeeeep....sound is back! I'm a lilttle pissed at myself, but it is what it is. Now I'm going to try the ruebadue wire coil!

[6666]

Thanks. No oscilloscope, however I think I figured out the problem. It's almost too embarrassing to write it, but in case some other noob comes along and reads this thread...

I looked at my soldering and didn't see any pads touching. Everything looked ok physically. I checked the values of all the transistors and I started replacing parts. The batteries were fully charged. Anyway, after pulling my hair out, I took out my magnifying lense to scrutinize...I actually did this a couple of times, and resoldered a lot of what was there, hoping that maybe somewhere the solder wasn't making full contact. To make a very short story even longer...I saw a little whitish/bluish colored stuff, which I saw a few times before, and thought it was just residue from cleaning or from soldering and resoldering. On closer inspection, I noticed that there was actually a break in the trace - it was really hard to see, and I doubt I would have ever seen it with my eyes. I added a little copper tape, and after wasting hours and hours...beeeeep....sound is back! I'm a lilttle pissed at myself, but it is what it is. Now I'm going to try the ruebadue wire coil!

[waltr]

Good job. Yes, little things like that are hard to find.

[AK48]

hello imrubin
I have almost the same problem with my SMPI from white's,
could you put a picture of the break in the trace , thank you

[lmrubin]

I wish I could...I'll see if I can find another and what I did.

Basically, you know how you can see lines that are "under" the color of the board? Meaning you can see the lines (traces) of where a pad links to another pad. There's a strip of copper underneath the blue board (your color may be different). Well, I had somehow broken that line - all it takes is a stray sharp edge...from tweezers, or soldering iron, etc. Here's what I did - I used an Exacto knife to lightly scratch away say 1/8" of the blue paint on the opposite end of the break to expose the copper underneath (so you have the soldered beginning pad, then the trace starts, then the break, then the trace picks up again to the pad at the end) . Then I stuck a piece of copper tape (very small) touching the first pad on one side and ending after it touches/covers the exposed copper on the other side of the break. So the tape is basically a bridge over the break. Then I add a little solder to connect the beginning pad to the copper tape which is now filling the gap over where the break was. That should make sense?

But then I did another stupid thing that I'll post separately...

[AK48]

thank you men !