Quote from: crashoveride54902 on February 25, 2014, 11:46:41 PM

Quote from: bondus on February 25, 2014, 11:31:49 PM

Quote from: tolip_wen on February 25, 2014, 10:52:42 AM

Quote from: bondus on February 25, 2014, 12:30:57 AM

I will start with a warning. It is unknown if this is safe. KnC may have turned off the VRMs due to that there is a problem with the design.
You board might burn! On the other hand they ran with all VRMs turned on for a few weeks when they were new without any major issues.
I have run a few machines with 8VRMs for almost 2 weeks without problems. Some machines will start buzzing pretty loud, I have no idea why.

bondus thx !

Is the buzzing 1 VRM, ALL VRM's, or just a few?

DISCLAIMER:
I have Oct 4 VRM hardware.
I have extra VRM's(and associated parts) that I thought to install, that is why I have studied it.
At this point not cost effective, at over .25 BTC ( >USD$125 ) per ASIC in VRM's alone.

I have 'ideas' why 8 VRM's MIGHT misbehave.
(notice the lack of absolutes in the above sentence!)

** Massive text with ideas to explain buzzing and safety ***

Too bad I do not have access to a proper electronics lab Sad

Most of your ideas could be easily tested with a scope and some other basic tools.

But I have made some other observations that might be interesting:

Iout and Vout from the two VRMs in the pairs are not even.

Typical values (as reported by the VRMs):
table]

VRM Nr	V	A
0	0.8154	24.8750
1	0.7998	27.6250
2	0.8066	30.3125
3	0.8164	26.8125
4	0.8184	30.5000
5	0.8096	30.0000
6	0.8235	27.6250
7	0.8164	31.8750

0,3 and 6 have slightly higher voltage that the other VRM in each pair. The pair 4,5 is pretty even.
Current is a bit higher on the VRMs with lower voltage. It looks the same on many different boards.
You would expect voltage and current to be the same on both VRMs in a pair. Odd.

The buzzing gets louder the more power you use. You can clearly hear when a block is found

I haven't had time yet to open a box and check what VRMs are buzzing.

Since you have ordered the parts you must know the value of then RTUNE and RTrim resistors for the VRMs?

hmm maybe you should copy my 8vrm board then Cheesy

i have to stick my ear next to it to hear a faint buzzing....

tiozes: ppl been having problems going from 1.0 to 99.1 tune or i think any tune...should go back to 99fw then 99.1 tune

yes, with 0.99.1 has returned everything to normal, go fuck have you done for 4Vrms jupiter of October.

I was hoping to pass my jupiter 221 as 231 dies.

That could put a V max each die?

temperatures are at 56 ° C maximum and have sinks in the vrms.

654Gh avg a 221

regards