Troubleshooting an electric/electronic intermittent takes patience. With headphones on, I would start by:
1. lightly torquing the body against the head, to see whether physical stress on the board connections triggers the failure
2. after removing the housing tube, with a plastic fiddlestick push on either end of all three circuit boards, bending it up and down trying to trigger failure
3. doing the same on each electronic component: wiggling, bending, pushing and pulling
4. doing the same on all wire connections
If none of that yields any results, wait for the signal to drop out, then:
5. measure incoming voltages at both 2.2KΩ resistors, then:
6. measure drain voltage at the 47kΩ resistor (should be around 22VDC incoming and 10VDC on the drain side of the resistor), then:
7. turn the mic off and measure transformer secondary resistance (should be around 18Ω with 200Ω output strapping), then:
8. disconnect one of the primary wires and measure across the primary (should be around 650Ω)
Report back your findings.
KH
