Troubleshooting Music Lights (ML1)
Assembled my ML1 kit years ago; it's been packed away and I decided to take it out. Unfortunately, it doesn't work; no light at all.
I've double/triple-checked the solder joints.
Transformer: primary coil measures ~0.8 Ohm, and secondary coil ~20 Ohm.
The primary coil is fed from the audio input.
I removed the Mid and Low pots in an attempt to isolate the problem.
If I short the SCR, Anode--Cathode, or Anode--Gate, the light turns on.
Any ideas on where to start? Which piece is most likely to fail?
Related question: By tapping around randomly with one probe, I can trigger quick flashes of the lightbulb. Is this an effect of capacitive coupling?