Lowyat.NET: Latest topics by ff7yta

Hard disk cluster size

ff7yta — Sat, 14 Nov 2009 21:09:40 +0800

I was wondering, what cluster size would be best in terms of performance for a partition size of 1.3 TB?

Closed

ff7yta — Mon, 21 Sep 2009 21:10:59 +0800

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ff7yta — Thu, 20 Aug 2009 00:41:42 +0800

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ff7yta — Tue, 21 Jul 2009 13:29:04 +0800

Item(s):
Buying any dual core socket 939 processor.
The faster the better.

Warranty: 3 days please

Dealing method: COD @ Kampar, perak. Else postage

|WTS| Yamaha Ego Original Sport Rim

ff7yta — Sat, 14 Feb 2009 15:42:10 +0800

Item(s):
Yamaha Ego Original 14 Inch Sport Rim
- Front (new < RM100)

Dealing method: COD @ serdang or somewhere close by

Item(s) conditions:
Rims bought in one set. An accident caused the back rim to bent slightly and braking not smooth. Changed the back rim only, the front one is still unopened.

Reason for sale:

|WTS| Canon IP3300 ►►►

ff7yta — Sat, 20 Sep 2008 23:03:13 +0800

Item(s): Canon IP3300 (Out of ink) Can be sold separately.
1. Printer body
2. Printer Head (Sold to rabbit_fire)
3. Cartridges (5-8-8-8) (Black-Cyan-Magenta-Yellow)

Package includes: Box, CD, Cables,

Price: Offer me

Warranty: DOA

Dealing method: COD @ Serdang

Item(s) conditions: Used for few months. Left sitting around for many months.

Reason for sale: Funding

The cyan and magenta cartridge is not responding.

The printer cassette loader has broken off. But still 100% usable.

» Click to show Spoiler - click again to hide... «

Chimei LCD Repair

ff7yta — Wed, 03 Sep 2008 22:55:55 +0800

I have a cracked chimei LCD that I want to repair. Where can I get a quotation and location?

Closed

ff7yta — Fri, 15 Aug 2008 15:14:51 +0800

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Where can I find special ink for canon inkjet

ff7yta — Fri, 04 Jul 2008 18:04:40 +0800

Where can I find special ink for canon inkjet printer to print on non paper surfaces like plastic etc...

I thought of having water transfer ink to do the job but I cannot find any retailer in malaysia. Anyone can suggest me ideas?

Closed

ff7yta — Thu, 26 Jun 2008 20:48:19 +0800

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Fan's bearing description

ff7yta — Thu, 12 Jun 2008 23:21:33 +0800

Adopted from http://www.digit-life.com/articles2/cpucoo...-august2k2.html

QUOTE(http://www.digit-life.com/articles2/cpucoolersinquestion/fans-inquestion-august2k2.html)

Fans are playing a crucial role in modern technologies of computer cooling. Being the main component of forced air cooling systems, they are widely used in processor coolers, cooling devices for hard drives and video cards, systems units, power units, peripherals etc. In the Part 1 we studied all most important features concerning fans, their fundamental parameters, characteristics and working properties. Today we will look again at such devices, this time from the technical viewpoint and take into account all important technical details.
Fan's design and peculiarities of functioning
Modern direct-current fans are based on one- or two-phase thyratron motors. Such motors consist of two main parts: control circuit and inductor mechanism. The latter is a rotor-stator tandem where a rotor is an annular permanent magnet and a stator is a four-polar (sometimes 6-polar) inductor.

[center][/center]

A control circuit can be different. The most popular variant is based on a chip-driver with an integrated Hall device (Analog Technology ATS276/277 chips and their clones are usually used); it fulfills matched inductor's phase switching which allows the latter to induce a rotating magnetic field in the rotor-stator space and make the rotor move. Some advanced fans can use much more complicated and multifunctional chips-drivers coming with a tachometer control, security circuits for a circuit feeder and detection of impeller stoppage (for example, Sanyo LB1663 chip). But such control circuits are not very popular among manufacturers and are rather an exclusion than a rule.

[center][/center]

Now let's take a look at the mechanical part of a fan, i.e. its bearings. As we mentioned in Part 1, the rotor's (impeller's) shaft can be attached to the base using:

* sleeve bearing
* combined bearing (one sleeve bearing - one ball bearing)
* two ball bearings

Let's start with a sleeve bearing. Not so long ago such bearing was quite popular thanks to its low prime cost and a simple technology of production of such fans: a sleeve bearing is made in the form of a primitive bronze bush, a steel rotor shaft is mounted in the bearing with a plastic locking ring, and the bush is plugged up with two rubber glands attached to the shaft of each its end (the glands prevent grease leakage from the shaft-bearing gap).

[center][/center]

At first glance, everything looks OK. But if you look closer at a sleeve bearing you will notice several quite sad downsides.

First disadvantage. As there is a gap between the bearing's internal surface and the shaft, the impeller's shaft rattles inside the bearing (beating of the shaft is rather noticeable). That is why it makes an abrasive effect on a bearing: its cross section becomes ellipsoidal instead of being round. The shaft begins rotating unstably, its noise level increases (creaking and tapping appears in the fan's noise spectrum), power consumption rises and the fan heats up more. If the impeller is unbalanced, the bearing can get damaged quite quickly and the fan will die.

Second disadvantage. Grease can leak out from the shaft-bearing gap (despite glands and other precautions). As a result, the shaft and the bearing run against each other without any grease, the impeller's speed falls down and a noise level increases.

Third disadvantage. The shaft-bearing gap is made as narrow as possible to prevent an ellipsoidal shape of the bearing. But if grease inside the bearing is not enough or it's of low quality, the motor starts with difficulty which causes increase in current consumption and power dissipation (sometimes it may result in stoppage of the impeller and damage of the fan). And the fan's service life becomes shorter.

Fourth disadvantage. Fans based on sleeve bearings can't stand high ambient temperatures. Over 50-60°C the service life of such fans gets much shorter and usually doesn't exceed 5,000 hours.

All these disadvantages coupled with careless attitude toward product quality of certain manufacturers make doubtful usage of fans based on sleeve bearings in computer cooling systems where reliability is of the utmost importance. Such fans are quite cheap, but a greedy man pays twice or even more. Because damage of a fan of a processor's cooler may cause death of the processor itself.

Now let's turn to a combined model based on sleeve and ball bearings.

[center][/center]

I can't say such a combo solves all problems, but it seats on a higher level.

First of all, a sleeve bearing plays a subsidiary role (it's used as a shunt). A ball bearing takes the main load. And as rolling friction is less than sliding friction, the motor starts easier and the power dissipated is lower.

Secondly, a combined construction is less sensitive to a disbalance of an impeller. The shaft's beatings are reduced to a great degree by a ball bearing, and probability of an ellipsoidal shape of the bush and its damage is minimal (provided that technical regulations at the plant are not neglected and quality of finished products is strictly controlled).

At last, the combined fans can work in quite complicated conditions (at high ambient temperatures and increased air humidity).

However, the problem of grease leakage from the bush/shaft gap is not solved here, which may result in a slower rotation of the impeller and a higher noise level. Sometimes too sticky or lubricating grease can be used, but they even worsen the situation: grease is pressed out of the gap anyway, or, which is worse, thickens forming hard particles. At worst, a shaft jams, and the fan gets damaged.

The last fan we have to estimate today is one based on two ball bearings.

[center][/center]

Although this construction is not a cure-all, fans on two ball bearings are preferable for processor coolers, power units and system units.

The main advantage of a design based on two ball bearings is high reliability and durability of such fans. Two ball bearings excellently supplement each other, provide an easy start of a motor and steady rotation of an impeller. Consumed power of such fans is as a rule lower as compared with products based on a combined bearing or a sleeve one which improves thermal conditions and increases reliability of their operation. Besides, fans based two ball bearings do not require special grease, the problem of grease leakage does not exist.

Another advantage - a fan based on two ball bearings is a well balanced construction. A spiral spring set on a shaft between the first bearing and the impeller eliminates a possible disbalance of a rotor, and residual beating of the shaft will be mutually made up for by two ball bearings. As a result, the fan works stably in almost any position relative to the gravity vector.

The last important advantage is that fans based on two ball bearings are able to work stably and reliably in very high ambient temperature (up to 70-90°C)

The only disadvantage of such devices is their high cost. But high-quality miniature ball bearings are very complicated and labor-intensive products (one high-precision ball bearing can cost $3-5 and higher while one miniature sleeve bearing is usually not dearer than 10 c). That is why high prices top-quality fans are offered at are inevitable. There is nothing to do. Health of a computer system is anyway more expensive.

Well, that's all I had to say about the electromechanical part of fans, and now we are turning to the last crucial technical aspect of an aerodynamic character.
Performance curve (metric characteristic) of fans
Last time we studied one of the most important characteristics of a fan - its performance. This parameter is always specified in the technical documentation of fans and it allows us estimate objectively their effectiveness. But you must remember that the performance is specified for ideal conditions, i.e. when a fan works in the open and there are no any obstacles for an air flow. In real conditions a fan is installed inside some system, be it a computer case, a power unit, a heatsink, ai airway etc. All such objects put obstacles in the way of an air flow formed by a fan (flow resistance of a fan's working circuit is different from zero). As a result, a real performance level can be actually much lower than the volume air flow rate which is usually specified on packages of fans, processor coolers etc.

Apart from performance any fan possesses one more weighty aerodynamic parameter - static pressure. This value is measured in inches (or millimeters) of water and shows a difference in pressure of an air flow formed by the fan and ambient pressure (atmosphere pressure).

There is a clear dependence between the fan's performance and static pressure of its air flow. It is defined in a special pressure chamber and called performance curve (metering characteristic) of a fan.

[center][/center]

Two extreme values are shown in the technical documentation of manufacturers. Pressure of the air flow at its zero volume rate (zero performance), i.e. when the fan runs idle (no flow at all), is taken as its static pressure. It happens when its resistive action (flow resistance) of the channel is so high that the fan is not able to pump air through this channel. Such situation never occurs in computer cooling, but it can take place in other spheres of application of fans.

Volume flow rate at the static pressure equal to zero, i.e. when a fan works to its full capacity and gets no obstacles from the channel, is taken as performance. In practice such situation is impossible at all and can be emulated only in a special pressure chamber.

Well, let's call it a day, and next time we will continue speaking about a metering characteristic of fans and look at its practical use closely.

How to oil sleeve bearing fans

ff7yta — Thu, 12 Jun 2008 23:15:13 +0800

Adopted from http://www.dansdata.com/fanmaint.htm

QUOTE(http://www.dansdata.com/fanmaint.htm)

Your computer's life probably depends on fans. At least two, in pretty much all current PCs - a little fast one on the CPU cooler, and a bigger slower one in the power supply. Many PCs have a second 80mm fan mounted in the front of the case to help with air flow. And some... special... PCs have a veritable wind farm in there, competing for space with the neon lights and fluffy dice.

The trouble is - fans don't last forever.

The motors in modern computer fans are brushless units which will last, by computer standards, forever. But the spindle on which the fan turns sits in a bearing, and bearings wear out.

The most common, and cheapest, kind of fan bearing is the "sleeve" type. It's a simple design; the steel shaft just sits in a solid bushing. The bushing is likely to be made from sintered bronze, which is porous metal that's impregnated with lubricant at the factory. When that lubricant runs out, the bearing will start to wear, and make a distinctive buzz. The wear will get worse and worse, the buzz louder and louder, and the fan slower and slower, until finally it stops.

This process can take weeks for larger, slower fans, but can happen a lot faster to smaller, higher speed fans. A failed CPU cooler fan probably won't leave you with a dead CPU, but it will make your computer hopelessly flaky until it's replaced.

The other kind of bearing is the "ballrace", commonly just called a "ball bearing".

[center][/center]

This is what a ballrace looks like on the inside - a ring of steel balls in the space between outer and inner rings of metal. The balls roll between the rings, allowing them to rotate freely.

Ballraces last better than cheap sleeve bearings; some higher-tech sleeve bearings now exist which may well outlast ball bearings, but most computer fans use the cheap type. When ball bearings finally do fail, though, they can seize rock solid. Once that happens, they're junk.

If you catch a deteriorating bearing before it gets too bad, though, you can make the fan live a lot longer with a few drops of oil. If you oil a bearing before it shows any symptoms, the thing can live for a lot longer than the manufacturers expected.

So how do you oil a fan bearing?

In almost all cases, it's actually quite easy.

First, you need to get access to the motor side of the fan, which will be covered by a sticker.

[center][/center]

Most ATX Power Supply Units (PSUs), including this one, have their fan mounted so that you can see the sticker through the finger guard. Undo the four screws holding the finger guard in place (they also hold the fan in place, but it probably won't have much room to move even without them) and you can get at the sticker side of the fan without taking the lid off the PSU.

[center][/center]

Now, carefully peel back the sticker. If you damage it, don't panic; you can just replace it with a piece of tape.

Small fans often seal the bearing with nothing but the sticker, but larger ones usually have a round plastic cap under the sticker. This fan's got a rubber cap, which is easy enough to pop out.

[center][/center]

Inside, you can see the bearing. This fan's got a ball bearing; sleeve bearings are less interesting looking.

[center][/center]

Now, oil that sucker.

What you oil it with isn't too critical. Pretty much any light oil will do. Plain old 3-IN-ONE or sewing machine oil from the supermarket is fine. Note that the usual red-label 3-IN-ONE that I'm using above has a vegetable oil base, and may gum things up if used over and over. This isn't likely to be a big problem with fan bearings (it's usually only an issue in automotive and other high temperature applications), but if you're concerned then you should get the blue-label mineral based version.

Spray-can oils with an applicator tube can be handy for oiling fans in awkward spots, if you can avoid spraying oil all over the place.

Do not, however, use WD-40 or similar products. WD-40 is has great penetration, displaces water well, and loosens rust - but it's a lousy lubricant. It's mainly kerosene, and the oil that's left when the kerosene evaporates may be more than adequate for stopping a gate-hinge from squeaking, but won't last long in a fan bearing.

Resist the urge to try to fill the bearing well completely with oil. If the fan isn't installed bearing-side-up, excess oil in the well will leak out rapidly, pretty much regardless of what you stick over the well. Even if the bearing side is upwards, centrifugal force when the fan's running will allow a surprising amount of the oil to escape.

(Yes, yes, I know that centrifugal force doesn't really exist.)

If you want to fill the well with oil and let the fan sit for a while, so the oil can permeate the bearing a bit, fine. But soak up the excess with something before you put the sticker back on, or you'll just make a mess. You'll probably also need to de-grease the plastic back of the fan, in order to get the sticker to adhere again.

The above instructions apply to pretty much every rotary fan you'll find in a PC - and they'll continue to, at least until things like these become popular.

[center][/center]

Even large fans, like this 120mm mains powered unit, have the same bearing arrangement as much smaller models.

[center][/center]

Apart from the danger of equipment failure caused by a dead fan, you can't always easily replace a fan if it fails. So it pays to keep unusual fans oiled.

[center][/center]

This little fan, in a network switch, doesn't look all that weird. But it's actually a five volt unit, not the usual 12 volts, so it'd be difficult to replace.

How to maintain fan ball bearings?

ff7yta — Wed, 11 Jun 2008 00:25:01 +0800

How to maintain fan ball bearings? How do I put oil into them?

AC RYAN Fans & Products

ff7yta — Tue, 10 Jun 2008 13:41:53 +0800

Whats so special about AC RYAN Fans & its products?

Slow access to imageshack (only)

ff7yta — Sat, 24 May 2008 14:15:09 +0800

I'm a single user for a 1 mbps streamyx line. Going to any websites, the webpages open instantly. Only when going into imageshack, it takes 15 minutes to display a 640 x 480 image. Uploading a picture is never successful... This problem has been ongoing for a month. Why? And how to solve this?

Computer specifications:
Win XP SP2
Mozilla Firefox 2.0.0.14
PC Tools Antivirus
No Firewall turned on

I have tried:
1. Clear firefox cache
2. Reinstall firefox
3. On / off firewall
4. Turn off everything online (eg. windows live messenger, torrent, download manager)
5. Turn off antivirus (this was the most stupid thing i did. Hit by virus instantly)
6. Use internet explorer 7 (same, slow browsing)

Anything I left out?

Project: Logic Fibre

ff7yta — Mon, 24 Mar 2008 15:06:55 +0800

Day 1:
Well, I have nothing to do and very bored at home, so I decided to mod me mouse and took all the pictures for fun. Now, to post them and show off my work

Tools required for serious action:
One old mouse, operated and ready to go:

Sizzarga:

Carbon Fibre Sticker, Water, Julie's Cookies:

Puncher?:

Other stuffs:

Knife for removing mouse feets and screw driver for screwing the mouse. Make the mouse high a bit so it opens easily...

Upgrading Graphics Card

ff7yta — Fri, 18 Jan 2008 18:26:11 +0800

Here are my computer specs:
1. Abit NF7, Socket A, AGP Support only
2. Thoroughbred @ 2200 Mhz
3. 512 MB RAM
4. NVIDIA FX5200 AGP <- This buddy needs to be changed

I am thinking of upgrading my graphics card so I can increase the details of my NFS Pro Speed. But I was wondering, which AGP graphics card I am bound maximum to upgrade to? Unlimited budget for GPU upgrade. GPU only.

Mozilla Firefox 3 Beta 2

ff7yta — Sun, 13 Jan 2008 22:26:44 +0800

I am using the latest mozilla firefox 3 beta 2 and i am getting very annoyed by the downloading manager that automatically scans my downloaded files after it finishes. Is there a way or method to turn off this auto scan?

Graphic Card to TV OUT

ff7yta — Sat, 12 Jan 2008 21:53:08 +0800

I want to set up a TV as secondary display but I dont know what cables or extra stuffs that I need. Anyone can guide me?

Graphical drawing error in game

ff7yta — Fri, 11 Jan 2008 23:24:58 +0800

I'm trying to play Death to Spies, just recently got it. But now having a major problem.

Referring to the pictures:

The textures are all white in color. I'm unable to play as I cant see anything...
In the readme, this game recommends Nvidia 5200 which is what i am currently using right now... Not applying any overclocking to graphics card either. Already tried to change to game internal options but no avail.

What causes this problem? How to overcome it?