On Thu, Oct 27, 2022 at 03:03 AM, Bill W1PA wrote:
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.
This is used on transmit - the limit current would probably be quite high >2A.
I would not expect it to trigger at 0.5A even if it was active during RX as this is within the normal operating current range with volume up.
You can bridge Q1104 on the top side by connecting 13.8US (3 pins to PA) to TP1084 (emitter of Q1082).
Now the radios power will stay on and you can see what the voltages are, and check how much power it is using, and check that voltages (like the main +5) are correctly reaching the front panel.
To turn off, the front panel must be seeing an unexpected level on one of the lines that reach it.
There is not a lot of smarts on the main board - no processors or other digital devices that return anything to the front panel. i.e. it has to be some static level on one of the lines.
