Jaycar troubles

Hello,

I've been trying to get the mk II Jaycar theremin to work, most recently I am getting no voltage reading and no continuity between ground and TP2..

There is 9V at TP1, however you should know that I have already taken the liberty of doing the first two of Thierry's mods: adding the two potentiometers for fine pitch and fine volume tuning.

I also have replaced 2 of the RF coils because I messed two of them up with a metal screwdriver. I bought a set of 4 coils for AM radio and the label indicated that the 1st and 2nd IFT (the YELLOW and WHITE coils) were interchangeable, so I used both of those.

I have also already gone ahead and started making a hexagonal box and have 10mm aluminium rods for the antenae.

Is there anything I can do to test what is going wrong? I only have a multimeter to use.

Thanks

A "howto systematically diagnose a Jaycar theremin" can be found here: http://www.thereminworld.com/Forums/T/26521/diagnosing-jaycarepesilicon-chipkees-enkelaar-theremins

A multimeter will most probably not be enough... I think that a small requency counter and at least a cheap handheld oscilloscope with 8MHz sampling rate and 8bit resolution are the absolute minimum prerequisites for successfully debugging theremin circuits.

OK thanks, do you think a sound card oscilloscope would work?

A sound card oscilloscope will definitively not work because its sample rate is about hundred times too low. As I wrote above, a minimum sample rate of 8 Megasamples per second is needed to have a good representation of the RF signals found in a Jaycar which are around 500kHz, so that one cycle is represented by 16 samples.

Sound cards have sampling rates from 48 ks/sec to 192 ks/sec which means that you'd have ways less than one sample per cycle.