Quote from: miniasic on January 23, 2014, 08:42:35 AM

Hi,

I found a simple method to increase the voltage without soldering. On the image you can see several measurement points for different voltages on the antminer board. The USB voltage can be found between the outer pins of the the connector (red = 5V and black = Ground). Then we have two points near the USB - Serial converter which give us about 3.3V. Next you can find 1.1V close to U5 what seems to be the communication voltage of the ASIC. The relevant voltage for operation is the green point near U2. There are 0.8V (or in my case 0.86V in factory mode, what coud explain the differences in overclockability of the devices). Now to the interesting part. There is no need to replace both R1 and R2 just to follow the table in the U1 manual. The table there is more or less the same as in the AOZ1021AI datasheet. What I did was to use a medium hard pencil and do 3-4 strokes between the R2 connectors, plugged the device in an measured between black and green and voila I got 1.06V. You could easily do just one stroke for the start and see what happens with operation voltage. lesser strokes should give a higher resistance what would lower the voltage, so no risk in trying this. Unfotunately I "ruined" my device before this test (what made me bold enough to try it this way) so I can't tell you what hash rate I coud make after this modification. My antminer doesn't reach more than 450MHs as I can't clock it higher than 57.81MHz (0x1207). Somehow I messed up the PLL in earlier tests with small steps in clock rate and never made the device recover Embarrassed

Greetings,

miniasic.

Makes sense, as you are closing the circuit. The only problem I forsee is that without knowing the resistance of the pencil mark, you will not know the voltage. In your case, it worked out to be around 10.3KOhms.

EDIT: Well this is fabulous. Battery died on my multimeter right as I went to test how much resistance a pencil stroke has. None of my three alarm clocks have a 9V battery in them, and I can't find a 9V DC power supply. I'm not gonna wire up 6 AAs in series either...

EDIT EDIT: Now the doubt sets in that it was really the battery, because this meter has been wonky sometimes. Off to look for another multimeter to test the battery with...

Meh, not walking up to the shop when it's 10 below at 4 am, be back later today...