On Fri, Oct 4, 2024 at 06:17 PM, Stan Dye wrote:
Note that the general power-on process is this:
1 - pressing the power-on button turns on Q103/Q105, which puts the voltage from the input jack on the +12V rail
2 - this +12V goes to the input of IC101 which creates the initial 3.3V VDD voltage via D103, which is also connected at the top of D109.
3 - this VDD voltage powers on the CPU
?
Thank you Stan.? I now have some hope that the problem may lie with the power circuit.
1 - When I press the power on button I see +12v on the +12v rail.
2a. I measure 2.17v on IC101 Vo pin and 1.2v on Vdd.? My measurements are with a digital meter measuring voltage so may not be precise.
Are there any further checks that I can make before replacing D109?
Kevin MW0KXN