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All of my Blade 1500 workstations (blue) generate a strange kind of howling
noise. Taking a close look with the case opened, I know now that it's
caused by the case fans, which accelerate/decelerate about once or twice
per second - one can hear that, and even see it when looking at the
fan blades.

One can see it in prtdiag -v output, too. I used:

while test 1 = 1
do
date
prtdiag -v | egrep 'rpm|Ambient'
done

The temperature is constant, but the fan rpm of both case fans is changing
frequently. I guess the problem could easily be solved in software, by
modifying the fan speed control. Is it possible to do this via any Solaris
command (picl/*fru*/whatever) ? I'd really like to check whether e.g.
setting the fans to a fixed rpm would resolve the noise problem.

If nothing else, I'd like to know if anybody else has this problem.

Running the fans on full-speed all the time would probably be less
disturbing than this pulsating sound.

I'm up-to-date on patches, and I just updated the OBP to the most recent
version, too (I hoped this could help, esp. after seeing "4816966: Need to
change Fan PWM Freq in OBP for Taco" in the OBP patch README, but to no
avail).

mp.
--
Systems Administrator | Institute of Scientific Computing | Univ. of Vienna

HI,

Martin Paul wrote:
> All of my Blade 1500 workstations (blue) generate a strange kind of howling
> noise. Taking a close look with the case opened, I know now that it's
> caused by the case fans, which accelerate/decelerate about once or twice
> per second - one can hear that, and even see it when looking at the
> fan blades.
>
> One can see it in prtdiag -v output, too. I used:
>
> while test 1 = 1
> do
> date
> prtdiag -v | egrep 'rpm|Ambient'
> done
>
> The temperature is constant, but the fan rpm of both case fans is changing
> frequently. I guess the problem could easily be solved in software, by
> modifying the fan speed control. Is it possible to do this via any Solaris
> command (picl/*fru*/whatever) ? I'd really like to check whether e.g.
> setting the fans to a fixed rpm would resolve the noise problem.
>
> If nothing else, I'd like to know if anybody else has this problem.
>
> Running the fans on full-speed all the time would probably be less
> disturbing than this pulsating sound.
>
> I'm up-to-date on patches, and I just updated the OBP to the most recent
> version, too (I hoped this could help, esp. after seeing "4816966: Need to
> change Fan PWM Freq in OBP for Taco" in the OBP patch README, but to no
> avail).
>
> mp.
I have this also on a Blade 1500 silver.


/michael

In article <434b90af$0$10578$3b214f66@usenet.univie.ac.at>, Martin Paul <map@par.univie.ac.at> wrote:
>All of my Blade 1500 workstations (blue) generate a strange kind of howling
>noise. Taking a close look with the case opened, I know now that it's
>caused by the case fans, which accelerate/decelerate about once or twice
>per second - one can hear that, and even see it when looking at the
>fan blades.
>

I had a 2500 (same vintage as the 1500)
that used to make a sorta clicking noise.
I think it was the PWM frequency aliasing with the
fan's rotation frequency.

I soldered a small electrolytic cap (note polarity, or it
turns into a firecracker) to the fans leads where
they entered the connector (unlatched barb,
pulled out pins, soldered, and replaced).
It smoothed out the voltage, and all the noise went away.
If you could find the right connectors you could
even put it inline, and plug it in (and remove for a
warrantee return, if needed (or just snip off
the cap, if you do it may way))

The cap I used was about a centimeter in diameter.
The value isn't critical, it just needs to be "big enough"
to smooth it out.
Make sure it's rated for more than 12 volts.


>One can see it in prtdiag -v output, too. I used:
>
> while test 1 = 1
> do
> date
> prtdiag -v | egrep 'rpm|Ambient'
> done
>
>The temperature is constant, but the fan rpm of both case fans is changing
>frequently. I guess the problem could easily be solved in software, by
>modifying the fan speed control. Is it possible to do this via any Solaris
>command (picl/*fru*/whatever) ? I'd really like to check whether e.g.
>setting the fans to a fixed rpm would resolve the noise problem.
>
>If nothing else, I'd like to know if anybody else has this problem.
>
>Running the fans on full-speed all the time would probably be less
>disturbing than this pulsating sound.
>
>I'm up-to-date on patches, and I just updated the OBP to the most recent
>version, too (I hoped this could help, esp. after seeing "4816966: Need to
>change Fan PWM Freq in OBP for Taco" in the OBP patch README, but to no
>avail).
>
>mp.

In comp.sys.sun.hardware x@x.x wrote:
> I soldered a small electrolytic cap (note polarity, or it
> turns into a firecracker) to the fans leads where
> they entered the connector (unlatched barb,
> pulled out pins, soldered, and replaced).

Thanks for the hint. Being more of a software guy, I hoped to
find a non-hardware solution. Too bad that there doesn't seem
to be any.

I decided to try a more radical approach to noise avoidance. I've
switched to a SunRay, and it seems as it's a viable way for all my
admin tasks. My test workstation (to be used when I need access to a
DVD-ROM drive, for example) has been sent into standby-mode - I
will resume it only when actually needed. A fan-free office at
last.

Problem is that I can hear a fan from the printer down the aisle,
and a radio from the neighbour office now

mp.
--
Systems Administrator | Institute of Scientific Computing | Univ. of Vienna

HI;

Martin Paul wrote:
> In comp.sys.sun.hardware x@x.x wrote:
>
>>I soldered a small electrolytic cap (note polarity, or it
>> turns into a firecracker) to the fans leads where
<snip>
>
> I decided to try a more radical approach to noise avoidance. I've
> switched to a SunRay, and it seems as it's a viable way for all my
> admin tasks. My test workstation (to be used when I need access to a
> DVD-ROM drive, for example) has been sent into standby-mode - I
> will resume it only when actually needed. A fan-free office at
> last.
>
> Problem is that I can hear a fan from the printer down the aisle,
> and a radio from the neighbour office now
>
> mp.

Thats always the case, no matter what changes is done, the problems is
just moved...

I also use SunRay instead to a Blade 2500 which is twice as bad as the
1500, with repect to noise that is


/michael