Logic gates made of bipolar transistors are called TTL, or transistor-transistor logic. CMOS chips use mosfets instead of bipolar transistors. The C in CMOS comes from the complimentary pair in a push-pull configuration.
There are two easy ways to kill mosfets by accident. The insulation between the gate and substrate is so thin that sometimes voltage as low as 12v can punch through and destroy it. Bipolar transistors are more tolerant to voltage spikes, they just avalanche and reset themselves. If you get a nearby strike (or a cat) that can induce enough voltage in a gate trace to exceed that breakdown voltage, its toast. Static sensitive doesn't mean you need to feel or hear the zap, its often far less.
Another risk to CMOS chips is if the device is powered when there is a nearby strike. Then, the required induced voltage is just that to turn on the mosfets. In a push-pull configuration, turning them both on at the same time results in certain destruction as they pass supply current straight to ground through the complimentary pair burning them both up.
My thinking earlier that the H-field audio probe may not work on a CMOS chip was flawed because there is still the drain current pulses, not sure why I was doubting it. My brain gets a little clouded sometimes lol.
Back to the radio. I was simply thinking that maybe running down the service manual's parts list searching IC numbers would give us a quick indication which are worth looking at, but thinking about it more, its probably most of them.
There are two easy ways to kill mosfets by accident. The insulation between the gate and substrate is so thin that sometimes voltage as low as 12v can punch through and destroy it. Bipolar transistors are more tolerant to voltage spikes, they just avalanche and reset themselves. If you get a nearby strike (or a cat) that can induce enough voltage in a gate trace to exceed that breakdown voltage, its toast. Static sensitive doesn't mean you need to feel or hear the zap, its often far less.
Another risk to CMOS chips is if the device is powered when there is a nearby strike. Then, the required induced voltage is just that to turn on the mosfets. In a push-pull configuration, turning them both on at the same time results in certain destruction as they pass supply current straight to ground through the complimentary pair burning them both up.
My thinking earlier that the H-field audio probe may not work on a CMOS chip was flawed because there is still the drain current pulses, not sure why I was doubting it. My brain gets a little clouded sometimes lol.
Back to the radio. I was simply thinking that maybe running down the service manual's parts list searching IC numbers would give us a quick indication which are worth looking at, but thinking about it more, its probably most of them.
