I had my surf pi kit on the test bench, all working fine apart from some some slow pulsing. I thought maybe some mains interference from either the house or the overhead power lines. So I thought I would take it outside and test it away from any possible interference.
Went to switch it on......nothing.
I bought it back in back on the test bench, still nothing. I re-soldered all the joints to no avail.
If I touch on side of R6 with my finger, I get a buzzing through the speaker, so I guess the op amp is working.
Here is a pic of the scope screen, the trace is identical to when it was working ok.
when I put a metal object over the coil the trace bends.
Anyone have any ideas as this is driving me nuts now
Thanks in advance
Went to switch it on......nothing.
I bought it back in back on the test bench, still nothing. I re-soldered all the joints to no avail.
If I touch on side of R6 with my finger, I get a buzzing through the speaker, so I guess the op amp is working.
Here is a pic of the scope screen, the trace is identical to when it was working ok.
when I put a metal object over the coil the trace bends.
Anyone have any ideas as this is driving me nuts now

Thanks in advance