Hi all,

Can anyone share some techniques/tips on how to swap chips on these hashboards.

I have a pile of donor boards and I'm trying to take some bad boards and make then good boards by swapping the good chips in.

But my technique apparently sucks ass -- it generally looks like i cant get enough solder on all the pads to make good contact.

My success rate is like 5% - terrible.

I use a hot-air at 400C to get the top heatsink off (thermal adhesive)
I preheat the bottom - use a hotair at around 250C to pull the chip.
I have no problem getting the chip off nicely, and also removing the rest of the thermal adhesive.

From that point ive tried all various combos of fluxing the PCB pads and putting solder down, trying to flux and re-tin the IC pads, not using flux, etc.
It always looks "too dry" around the pads and I'm sure they aren't making contact correctly.

I'm not really sure what else to do - perhaps my solder and flux are not correct?
I am using leaded solder 60/40 Sn/Pb and Amtech VS-213-A-TF flux

Will send sats for good tips!

i am interested in the same thing! a small bitcool immersion setup for 1 S9. what is the brand/model of the pump you are using? it has to have specific viton seals for it to be compatible.

i have not done it myself yet, but i think you can and should OC as much as you can (within cooling & dont forget power limits)
you might as well!

from what ive read the fluid lasts a long time and long term effects should be nothing, since the fluid is designed to be compatible with the materials in the asic. (i have read some incompatible fluid/materials will cause capacitors to bulge and become destroyed).

---

i pulled off all the heatsinks
that was some HOT fun. now i can understand the design & layout much better. i also pulled off the first 2 ASICs, that I thought were maybe shorting something to ground, but that did not help.
the buck/boost still makes noise. more investigation.

Just out of curiosity, how many versions of the S9 hashboard are there?

Edit Update: Found one of the 1V8 regulators putting out 1.5V and pulled the ASIC near it, and that seemed to make everything happier. No more noise from the switching supply. Now I'm debating if i want to put new BM1387 on there or just chalk up the board for more experimentation.

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

you might want to talk to SQRL, looks like they want to unload some. dont know the price.

you might get flamed but i think you aren't that far off on actual market price, especially at these quantities.

lol what you linked has nothing to do with the substratum being discussed here.

did you even read the github?