Quote from: stewdk on January 23, 2014, 10:25:59 PM

Quote from: twib2 on January 23, 2014, 10:09:38 PM

Quote from: stewdk on January 23, 2014, 10:06:45 PM

Quote from: robbcarpdm on January 23, 2014, 09:18:34 PM

Cap would be open circuit right not short.

Not if the capacitor was installed backwards. Which it was. More details to follow after I get the blade back online... IF I get it back online. Things are looking better now than a couple of hours ago at least.

Backwards?!? Ouch, their QC doesn't seem to have worked for the Q or the C for the non-early orders.

Reversed polarity. As bass ackwards as it gets.

After some tinkering, I finally got both blades up and hashing again. Like I said before, I narrowed it down to a short between 12V and GND on one of the modules. I temporarily removed the faulty module so I could run the good one while figuring out the problem.

At first I though it was due to the shitty soldering job:
http://i.imgur.com/3NYDjKE.png
http://i.imgur.com/3NYDjKE.png

But as it turns out it was actually due to the shitty soldering job. Electrolytic capacitors don't like to be connected backwards, contrary to what BTMine thinks. I'm honestly surprised it ran for as long as it did. This picture was after I had removed the C1 since I was doing the process of elimination.
http://i.imgur.com/dsmEwfn.png
http://i.imgur.com/dsmEwfn.png

I snapped a picture of the other working module. This is what it's supposed to look like:
http://i.imgur.com/GLxEWon.png
http://i.imgur.com/GLxEWon.png

Both caps removed:
http://i.imgur.com/0V4gx4z.png
http://i.imgur.com/0V4gx4z.png

Have a look at the schematic for this board http://downloads.canaan-creative.com/hardware/A3256/avalon/2013-11-30/HASH_PANEL/PDF/hash_panel.pdf
C1 is decoupling the 3.3V rail, and C2 is decoupling the 12V rail, and I confirmed this with my multimeter on the working module. The old C2 was obviously fried, and I just so happened to have a spare 470uF capacitor on hand. It's rated for 10V, not 16V, but that's okay, I just used it for C1. It was a bitch to solder since the ground plane acts like a huge heatsink.

http://i.imgur.com/5af6CAm.png
http://i.imgur.com/5af6CAm.png

If you're looking for replacement capacitors for yourself, you could use mouser as mtnminer suggested, or I personally like digikey.com.

stewdk

Posts

Merits