Why will my machine not re-start?
I have a similar issue to Powers up, no chime, three LEDs, then shuts off.. but with a very slightly different LED sequence.
Early 2008 24” 2.8 GHz Intel iMac; 4GB RAM; EMC No. 2211; Model No. A1225; OS X El Capitan with latest (last) security update (15G22010).
The machine was shut down during a recent vacation and on return it would not start normally. After re-setting SMC or PRAM it would run without a problem. But it required such re-setting after every shutdown.
Yesterday the machine worked fine – it had been on continuously for several days after starting with a PRAM re-set. I reinstalled OS X El Capitan, keeping the user data. Everything looked good and I subsequently closed down and restarted the machine normally 4 – 5 times (no re-sets).
Today the machine would not start. Resetting the SMC and PRAM does nothing. I replaced the PRAM battery. No change.
Symptoms: After pressing the power button I hear a fan operating and the chime starts; however the chime is cut short and the fan noise stops. The machine cannot be re-started until the mains plug is removed and replaced.
LED 1 lights up when it's plugged in. When I push the power button LEDs 2 and 3 and 4 light up sequentially. But as soon as LED #4 lights up it turns off, followed very rapidly by LEDs 3, 2 and 1.
Long story but a short question: Is the power supply the culprit, as in Steve Godun’s case, or, because LED #4 is coming on for a split second before all LEDs shut down, is something else in play?
Update (06/04/2019)
Bulge at end of capacitor C209 second from right:
Maybe slight bulges at end of two black capacitors C214 & C215:
Discoloured coil:
Esta é uma boa pergunta?
1 comentário
The two caps are indeed need to be replaced! Or, just replace the full PS unit.
The coils look OK, the coloring of the wire has to do with the gage of the wire and the supplier.
por Dan