I am starting to learn how to fix these boards, hope this is the right subforum
I'm hoping someone can give me a pointer where to look next. I feel like something is messed up with a 1V8 line *somewhere* but I can't really pinpoint it.
Symptoms (Hashboard 63 V1.9) :
- Board is not detected - I believe the kernel log showed "can't find sensors" and it hangs there.
- I measure .772 V to the base of Q86 (The 1V8 -> 3V3 level shift transistor for RX)
This is ~1.7 V on a good board. - Audible clicking from the power supply section. (Assuming one of the switching supplies - but don't know which.) Both 14V (14.32) and 9V (9.2 V) appear.
Makes me believe something is loading a supply somewhere. - I am reading .464 V on the RI testpoint near IC 2. (The third one in the chain - on what I believe is the 1st voltage domain).
IC | Good | Bad |
0 | 1.6 V | 0 V |
1 | 1.6 V | 0 V |
2 | 2 V | .464 V |
Does this pinpoint IC 0 & 1 as dead? When I compare RI resistance to ground I get roughly 200k on both good and bad.
Side question: Where the heck is 2V5 generated?
thanks for any nudge in the correct direction