[weblacky]

Thank you for coming back and updating the thread.

As some of us have indicated you're not unique in having this problem so it's interesting that replacing most of the functional component block worked.

Of course given the order of events we will never know exactly what needed to be replaced however I think it's a fair bet that a lot of those items probably needed to be replaced once the controller itself had been damaged.

Given your post said that initially the swapped controller functioned correctly for a moment until it nose dived again into failure. This could've easily indicated that yes it was damaged, but also that maybe it causes damage to one of the other components. Because again it was functioning after it hadn't functioned in its old footprint!

It's not out of the realm of possibility that a damaged controller also means that the items within its control may also have received some damage. I still believe replacing the cheaper stuff first was the better way to go but like you said it took replacing the controller and shotgunning a few other components.

For my own work in the future, could you please indicate which components you actually did solder on the board before you replaced the controller as the final step? You mentioned you purchased quite a few replacement components but that may not mean that you actually had to use them. Did you actually replace all the MOSFETs in that region or just the diodes?

Also in regards to the DS1780 I'm not 100% sure because most of the time SGI protected these with resistor networks, but individual sensor legs can be damaged and misreport voltage. I've seen this on two of my own repairs but I'm not hundred percent sure what causes the damage. It could be a voltage much higher than the anticipated sensing voltage. But I will agree they are extremely delicate and if you're going to replace a VRM section for repair if you don't get good reporting it is highly likely that the reporting mechanism was also damaged.

I tend to treat the DS1780 ICs more like canaries, in that yes they do warn of a voltage or environmental problem but they can die as they perform that warning.