Quote from: GandalfG on August 16, 2013, 04:12:04 PM

Quote from: GenTarkin on August 16, 2013, 02:49:02 PM

Quote from: GandalfG on August 16, 2013, 10:00:44 AM

Quote from: S M I L Y on August 16, 2013, 02:58:23 AM

Thanks lastbit and GandalfG for the info. I have access to a nice 12ghz oscilloscope and will take noise and ripple measurements of the output of the VR and see if it gets unstable past 20a.

Just took some measurements. At the top of the board closest to the VR im seeing 1.2v at the bottom im seeing 1.15v! Im surprised to see so much of a drop! They must have cheeped out on the amount of copper on the board.

I measure my board with my 100MHz oscilloscope with 1.3V mod and did not see noise on power lines. I check it now after over 10 days mining.
About drop:
Standby: 1.298V
395MHz:
1.278 on coil VR and nearest capacitor
1.268 first two chip
1.228 last chip.

I solder silver-plated wire 0,8mm across one board and check how its help.

Have any amps / watts per board power measurement?
Also, was this a b2 or b3? Did they change anything on the b3 miner boards?

I did not measure amps. It is Avalon clone based on B2 design that I build self. Buy PCB and parts from Strombom.
Actually have only 50 chip and patiently wait for supply from Bitsyncom.

Quote from: S M I L Y on August 16, 2013, 03:57:53 PM

Quote from: lastbit on August 16, 2013, 11:00:46 AM

50mv drop is horrible!

adding a couple thick wires from the output of the VR to the last chips should help a lot. although the problem could be a return path issue. I dont have my unit in front of me at the moment. I assume the bottom layer is Ground and the top is VCC? There may be an issue with the ground vias/pins not being able to handle the current.

Yes that huge drops are very undesirable. As I stated I solder wire and make measure again. I'm a little surprised that the original B1/B2 have a similar problem.
How about B3 machines that have changed design ? I see on one photos hash unit are probably grouped in 4 on one PCB and added thermal sensor on it.

Hey, do you have results of the wire mod improvement on voltage? dont recall seeing them...