I got my Time Machine out of storage after moving house, and remembered why it wasn't going
No 5v. Pretty well all the caps have been replaced, as has the Bridge Rectifier.
I have been through and tested for continuity and all looks good and tests fine on the bench.
When I remove all the load from the 5v circuit, I get 5 volts at the test points. As soon as any load goes on (doesn't really matter which board I connect) it drops down to ~half a volt. It is not consistent - sometimes it will be closer to a volt after I have restarted. The 12v is always closer to 14v (and a bit higher when the 5v is down)
Looking at Clays guides, and the circuit diagram it seems the next suspects are the voltage controller chip or the large transistor on the heatsink.
I don't want to just shotgun replace everything, and I'd prefer not to have to replace the IC.
What is the best way to test/diagnose to narrow down the problem ?
What voltages should I see on the other leads of the transistor or inputs/outputs of the IC?
And secondary question, recommended currently available parts to replace the 2N6057 transistor or MC1723CP voltage regulator chip.