New Member/multimeter thread ;-)

peteamer · Post by **peteamer** » Wed Jun 02, 2004 8:49 am

Gentlemen, we have amongst us a good number of very clued up I.T. personnel who just may be able to shed some light or offer a suggestion/solution to This problem.

Your reward ?

Further proving what a Damn fine Fella you are and the knowledge that you've helped recruit another member to the addiction... erm... I mean Worthy Cause.

Who in turn may be able to spread the 'Worthy Word' (i.e. Folding for SPCR)

BarCodeBlack writes that the crux of the problem is :

For a year or so now, I've been the proud owner of a compaq Proliant 5500R rackmount server

I now have the problem of trying to quieten it down. This machine is a hummer, and I mean a hum-dinger of a hummer!!

The fan specs are:

Make : Nidec Beta V (3 blade)
Size : 120 x 120 x 38
Voltage : 12v
Ampage : 8A

The connector on these fans are quite unique as I've never come across them before, which leads me to the idea that I may have difficulties finding quieter replacements. The fan utilises 4 cables (red, yellow and 2 black). An idea would be to disconnect the plastic connector and latch when I find replacements, but I can't be sure what the additional black wire is used for. Most other fans I've seen are 2 or 3 wire fans

Considering the light load on this machine at present, I can succesfully disconnect the fan blowing across the expansion slots, but as soon as I disconnect the fan for CPUs the machine shutsdown. This does have the advantage that the machine operates much quieter when shutdown.

I'm aware of 120mm fan alternatives from the likes of Panaflo, Evercool or Vantec, but my worries would be that I replace these fans, and the machine refuses to power up because of some fan monitoring.

If I can manage to quieten this thing down, I'll be willing to fold with it for the SPCR team

Any ideas Gentlemen?

And in anticipation of your expected usual exemplary standards... I'd like to... welcome BarCodeBlack to the fold.

Pete

haysdb · Post by **haysdb** » Tue Jun 08, 2004 9:42 pm

I don't know what the other black wire would be used for.

David

trodas · Post by **trodas** » Wed Jun 09, 2004 4:47 am

IMHO the colors of cable reasemble the colors of voltages used for computers - yellow +12V, red +5, black - ground.
Two blacks?
Look at the standard PSU connecttor for your HDD/CDROM

I think it SHOULD be this way done...

However fan should not need 2 voltages to operate, so my quess is, that the red wire is used for fan RPM measuring and therefore has to be connected to the replacement fan RPM output

The two grounds are probably just two grounds...

Some weird companies like IBM and such creating such "solutions" to prevent user replacing components

To be absolutely sure, let's connect multimeter and measure on the fly what's going on there

I bet on the double-ground and RPM on red and +12V on the yellow wire - unless the creator of this beast want us to confuse even more and use black wire for RPM, or something like that...

...after all, multimeter will cralify it

Now can I get some WUs?

dasman · Post by **dasman** » Wed Jun 09, 2004 9:59 am

I have a Dell PowerEdge server set up the same way -- 4 pins, 2 black on a square molex. Dell told me they were both grounds, but I can't say that I ever verified that. Someday I might try to swap the fans for something more "acoustically pleasing", but since the thing is in a closet, it doesn't really matter all that much to me...

Dave

mas92264 · Post by **mas92264** » Wed Jun 09, 2004 12:48 pm

...after all, multimeter will cralify it

trodas brings up a good point. Anyone that dinks around with computers much really should have a multimeter (aka vom) in their bag of tricks.

This one looks pretty good. There's a cheaper one also - about $16. Sears carries them also.

An analog meter is probably better for a newbie as the readings on digital multimeter can be confusing. I've got both, but I always reach for the analog meter first as it's just more comfortable.

M

sthayashi · Post by **sthayashi** » Wed Jun 09, 2004 1:36 pm

mas92264 wrote:An analog meter is probably better for a newbie as the readings on digital multimeter can be confusing. I've got both, but I always reach for the analog meter first as it's just more comfortable.

I have to politely disagree for exactly the same reasons on the VOM. If you put a Digital MultiMeter (DMM) in backwards, it almost always gives you the negative voltage. On some (like the one I have at work), it does the ranging for you.

Best of all, it's pretty damn easy to tell when the battery is dead on a DMM, whereas a VOM is a bit more difficult.

mas92264 · Post by **mas92264** » Wed Jun 09, 2004 1:45 pm

Phantom Issues!

If the reading (only when checking dc v or amps) is backwards, reverse the probes!

Low battery, iirc, applies only to ohm readings - you can't get the needle to zero when shorting the 2 probes. If so, change the batteries!

Go Analog!

M

mpteach · Post by **mpteach** » Wed Jun 09, 2004 7:02 pm

Digital meters are better for computer cuircuits because they have a higher intrenal resistance and thus cause less of a loading effect, also u cant damgage a digtal as easily by droping it.

mas92264 · Post by **mas92264** » Wed Jun 09, 2004 7:32 pm

I'm not giving up on this.

We're not talking about someone with a lot of electronic savvy, we're talking about someone that's never had a vom before. Someone that wants to know whether a wire is hot or a ground (always set your meter to check for volts, first!) Or, wants to know what that the voltage is 5, 7 or 12. They don't care that a dmm shows the voltage as 11.789 - which really doesn't give any additonal information than "about 11.8" does.

So what if a dmm says the value is 2.11 ohms? For all practical purposes, it's a closed circuit and an analog meter will instantly tell you this - no interpreting a numerical value required!

The analog meter that I have was purchased so long ago that I don't even remember when I bought it. It's been dropped, kicked and stepped on and still works great. Everyone should have one.

M

Putz · Post by **Putz** » Wed Jun 09, 2004 7:58 pm

I'd like to add my vote: I prefer analog. I'm an A/V techie, and get a lot of use out of my multimeters (I have one of each). If you work with multimeters a lot, then you'll know that both digital and analog VOMs have their advantages, and are better-suited to different tasks. However, for basic stuff like what mas is talking about, analog is my preference. And cheaper, too! For "Sunday" computer tinkerers (like Sunday mechanics), an analog will serve the purpose just fine, and not put too much of a dent in the wallet.

mpteach · Post by **mpteach** » Wed Jun 09, 2004 8:36 pm

if he only wants to know the voltages to with and acuracy of +- 3 volts he could use a flashlight battery, j/k

trodas · Post by **trodas** » Fri Jun 11, 2004 2:22 am

I have both, analog and digital ones too

The "very high imports resistance" of the digital ones have the drawbacks too. Measuring around power wires easily end with confusing numbers with digital, where analog is fine

So, after all, you have to know what the hell you are doing to use any of these

sthayashi raised a good point, tough. You don't need reverse the probes on digital, just interpret the - value as you have reverse the probes, but you do not,because you already see the value...

Better multimeter (digitals) have the "analog bar" on the bottom side of display too, so it sometimes alo help - as long you are not into the autorange stuff, well...

After all, Im pretty positive (back to the topic) that the two black wires are ground ones and it very easy to replace the fan then

Just measure and if the yellow vire giving about 12V (from 10 to 14 it's okay) and the red giving no signal then one stop the fan (use piece of soft material, not your fingers!

- if you like them

), then the pins are pretty much diagnosed right

BTW, another advantage of the analog is, that it did not measure well the impulses like the RPM impulses from the fan

(into short - you know that there is something different that only voltage, as the digital show there!) ...well, for this effect you have to combine the measurings from both devices

...and it's not bad idea to measure the frequency, after all

mas92264 · Post by **mas92264** » Fri Jun 11, 2004 5:17 am

New Member/Multimeter Thread.

M

peteamer · Post by **peteamer** » Fri Jun 11, 2004 5:28 am

Pete

mpteach · Post by **mpteach** » Fri Jun 11, 2004 5:39 am

trodas wrote:BTW, another advantage of the analog is, that it did not measure well the impulses like the RPM impulses from the fan
(into short - you know that there is something different that only voltage, as the digital show there!) ...well, for this effect you have to combine the measurings from both devices
...and it's not bad idea to measure the frequency, after all

IF you want to measure for pulsating signals on a analog or cheap digital then test it on RMS AC and ON DC if thiers a difference in the readings then ur signal is pulsating. Or you could buy a nice digital multimeter with a frequency counter built in. Antother advantage of digital.

peteamer · Post by **peteamer** » Sat Jun 12, 2004 12:54 am

I use a new member at work occasionaly and it's a digi, it helps when you don't have to worry abbout polarity. I also need it to be digi with 3 places after the decimal point so when I check the 12V line for voltage I know exactly whether there's power there or not....

Newer new members can also have temp probes inserted

and you can even have a psuedo osiliscope display and various other functions that I'm not going to be able to live with out when I finally get round to buying the rather expensive 'Fluke' I want so I can tell in a stylish way whether there's voltage... or not...

At work I more normally use a device that's a little shorter but wider than a pen, made of plastic with two 'contacts' near the top. Put the metal tip near a live cable whilst touching the correct contact and it will show voltage present on the display, touch a live component and it will show the voltage. Not accurate but as most testing is usualy is there voltage or not, it's perfect.

But it has to be said there is nothing better than using a genuine AVO analogue new member, it just 'feels' better. I used to have one years ago, you just cant beat the big old, never gonna break, heavy, chunky feel of an AVO new member.

Pete

mas92264 · Post by **mas92264** » Sat Jun 12, 2004 5:34 am

Pete, you're the best. If there's an award for "Best Thread Addition," my vote's for you.

M

peteamer · Post by **peteamer** » Sat Jun 12, 2004 5:47 am

mas,

I wonder if anyone else has noticed that to which you refer...

I'm actually concerned at the moment, cause reading my above post has made me laugh out loud..... again

... but I'm not really sure what's funny about it

Pete