LiteOn PA-6601-1A blows F1, etc.

[godonr]

The original thread I posted has mixed two problems associated with this Mac power supply. I would like this one to address the problem where the fuse (F1) blows along with R302, Q301, C301 and C302 and apparently anything else that gets in its way.
The other thread should be devoted to TOP249YN failures and repairs.
Hope this will help clear both problems with these supplies. As best I can tell, no one has been successful in repairing either, yet.
Thanks to all so far and I hope this will make it easier.

[godonr]

Re: LiteOn PA-6601-1A blows F1, etc.

Here's the latest I have on this repair. I've taken three of these which had some obvious damage... F1 open, R302 burnt, C301 and C302 split open and Q301 shorted... and replaced those components. In all three, that restored +5vsb and 25vsb but none of the other voltages.
Now looking for the source of missing 12v, etc. The supply uses a LM2596T @U802 in the area but there's also a transformer which looks like it supplies what's marked as 3.3v OC, 5v OC and 12v OC.
Problem I have here is on the supplies where vsb has been restored, I don't see anything with the meter on the secondary side of the transformer.
Seems odd all three would have the same problem. I now suspect the original cause of failure here was overheating since the 12v drives the fans on this unit.
Would welcome any ideas on how to proceed with troubleshooting this supply from this point.

[Toasty]

Re: LiteOn PA-6601-1A blows F1, etc.

I don't understand the sudden split in the topic after all this time. Just serves to confuse the masses...

The TOP problem is the rarer issue.

Toast

[godonr]

Re: LiteOn PA-6601-1A blows F1, etc.

The TOP problem was the original I encountered. It quickly became about the "R302 failure" and more people responded to that. Since I couldn't change the thread's name, I decided to try this. Of course, you're right.
I'd just like to resolve this problem. Do you have this board?
Sorry if I confused things... it's what I do best!