The power supply is chirping and it doesn't give the output voltage which it is supposed to.
The output voltage is this:
pin 3: fluctuates bewtween +1 and +2,7 - should be +5
pin 4: fluctuates bewtween +1,3 and +1,9 - should be +12
pin 5: fluctuates bewtween -0,4 and -2,3 -s hould be -12
pin 6: fluctuates bewtween -4 and -8 - should be -5
I'm not an electronic Expert and I only have a simple multimeter to measure it, so it's difficult to be precise.
It's measured with power supply pulled out of the machine, so it is without any load.
(I do have another power supply that works and the output is steady with the correct voltages without any load.)
The broken power supply failed after my apple II had been sitting in a box unused for about 25 years, and it worked fine for about a week with a few hours work time each day, before it developed the fault.
When I look at the capacitors and the other components of the power supply there isn't any "smoking gun", they all look fine (to my eye).
I have changed all the electrolytic capacitors and put in new ones, including the C7, and I have also changed the 0,1 uf MP capacitor.
That changed nothing.
The power supply is the ASTEC model AA11040C 230V.
Which component should I change now?