I've done some of this.?
- I put in an ammeter in line with power, and as the rig powers up, it gets to just over 0.5A draw before it shuts off.? As I understand it, the op-amp circuit near the power connector uses the common mode choke as a current sense device and sends a "power off" signal to the CPU to shut things down if it doesn't like what it sees.
- I did unsolder the finals power lead, and removed the two-pin connectors to the drivers, with no help --- thought for sure that would be it.
- I have both fuses on mine, despite what the service manual says -- both check fine.
- I confirmed each of the power rails (5, 6, 9, and 13V) as the rig tries to power up, on the main board and the front display board, but I will look again at the test points you mention.
The service manual is pretty good at describing the RX and TX chains, but there is very little on power-up, reset, and shut-down conditions for the CPU and radio in general --? a common issue with Yaesu service manuals.? Wish there more voltages noted in the schematics.
b
