Cheap PSU: Piece of junk or semi-decent?

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

Be glad But everything is once for the first time…

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

PC fans are hopeless as surgical instruments. Even large 200mm ones, with heavier propeller and greater rotational inertia, can be stopped harmlessly with one finger without shedding blood. I'm much more in awe of the high voltages inside a PSU than any PC fan.

[lti]

Re: Cheap PSU: Piece of junk or semi-decent?

I had one of these take a big chunk out of one of my fingers.

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

Some of them tend to be really sharp…

[tom66]

Re: Cheap PSU: Piece of junk or semi-decent?

They should have razor blades on the fan blades to be extra sure you lose a finger.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

I had one of these take a big chunk out of one of my fingers.

Sorry to hear that. That was a 3000rpm fan, at those high speeds they bite harder than the usual ~1500 rpm PC fan.

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

All those crappy PSUs with HAVE these 3k RPM fans if they are 80mm!

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

The Tacens Aura II 80mm fans that now dwell in my crappy PSU are 1500 rpm.

And that's one of the reasons for adding a second fan.

[Th3_uN1Qu3]

Re: Cheap PSU: Piece of junk or semi-decent?

Out of curiosity: What soundcard do you have in there? I used to have the same setup a couple years ago, including the push-pull fan arrangement on the PSU, both wired to 5v. Now the mobo i'm using for my dual Tualatins no longer has an ISA slot, but it has AGP 4x.

[eccerr0r]

Re: Cheap PSU: Piece of junk or semi-decent?

Also keep in mind the "suction" side eats fingers much more readily than the "blower" side ... trust me, I know...

If you had a "suction" side exposed please put a grille on it especially if it's high RPM or has a heavy rotor/fanblades.

[lti]

Re: Cheap PSU: Piece of junk or semi-decent?

Sorry to hear that. That was a 3000rpm fan, at those high speeds they bite harder than the usual ~1500 rpm PC fan.

I think it had unusually sharp edges on the blades. That fan is inside a power supply now. My finger healed surprisingly well.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

Wow, success beyond my expectations !

Plugged The Thing inside the good old PIII i440BX Tualatin-S @ 1600/150:

Posted OK, and BIOS reported 12.16V / 4.99V / 3.36V / -11.86V / -5.20V, with MMD reading 12.22V / 5.03V. Nice start .

Launched XP without a glitch, and found that what Aida64 and Speedfan now report is almost exactly the same what the DMM reads in the molex .

Then proceeded to test voltages under torture:

+5V is right on the mark! . +12V is within 2% . +3.3V is within 2% . Comp is granite-rock-stable now .

Also another unexpected benefit is a remarkable improvement in overall system cooling, CPU temps are 3~4 ºC lower now. Cool!


Thanks a lot gentlemen , this wouldn't have been possible without your help, patience and understanding. I'm learning in spades from you.

Token of gratitude:

... My finger healed surprisingly well ...

Glad to know .

... Out of curiosity: What soundcard do you have in there? ...

Sound Blaster AWE64 Gold.

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

Just curious what are thos bloody things on those fans?

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

Just curious what are thos bloody things on those fans?

'Though this be madness, yet there is method in't!'


Have a look at this table:

Notice the form with best (lowest) aerodynamic drag coefficient is teardrop (streamlined body), 0.04 .

But as they come, with flat center both at front and rear, PC fans behave like a short cylinder, with a higher Cd of 1.15 .


Now have a look at how they make the REAL fans:

Front hub & rear cone .

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

Can you achieve their precision? I guess not. So you will just centre-out the rotor and put more stress on bearings. Maybe even create some viration. That will bring you more noise than all the turbulence. People discovered it is sometimes better to add 100 RPM on better fan with same noise to achieve more than with all this mods. Similar with CPUs and stuff.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

The hubs are some ladies cosmetic shit caps, extremely light pieces of thin plastic, a couple grams in weight. The influence on propeller balancing of this minimal mass, so close to the axis of rotation, is negligible. No extra vibrations, don't sweat.

However the reduction in turbulence and noise are inmediately noticeable .

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

However the reduction in turbulence and noise are immediately noticeable .

Pics or didn't happen

[eccerr0r]

Re: Cheap PSU: Piece of junk or semi-decent?

I've noticed some fans have "heavy" hubs...This fan I'm holding right now has a metal shaft (brand/model is Sanyo Denki Pico Ace 15) and hub that the fan blades attach to, whearas most fans have one metal shaft connected to a plastic hub that the blades attach to. This is a 60mm x 10mm fan so it doesn't store way too much inertia, but scaled up to a 120mm I wouldn't put my finger into it...

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

Pics or didn't happen

Unfortunately I lack the means at home to photograph flow dynamics. I can however post some draws & pics to help you understand.

Just look at the front and rear fairings in the fans inside wind tunnels :

[momaka]

Re: Cheap PSU: Piece of junk or semi-decent?

Seems like I missed a lot of action in this thread. Well, congrats on getting the PSU working .

Added a DIY heatsink for the rectifier bridge.
http://www3.picturepush.com/photo/a/...g/11471416.jpg

If there ever was an award for spending the most time and effort to improve a cheap PSU, I think you would easily win . That said, this PSU is actually something I would trust now for reliably powering an old computer.

+5V is right on the mark!

Yup, these older Deer/Allied/L&C PSUs always seem to have spot-on 5V rail. I have a slightly older but still similar PSU - a Deer DR-250ATX powering a 933 MHz Pentium 3 PC with 2 HDDs and a Radeon 7200 video card. The 5V rail is rock-stable in mine as well, usually between 5.00 and 5.05V depending on load. The 5VSB is also very close to spot-on at 5.01V.

R1 is in parallel with second bigcap, R2 is in parallel with first bigcap.

That's crazy! This is the first time I'm seeing this. Normally, those resistors have the same resistance value. No idea why Deer/Allied did that.

Also keep in mind the "suction" side eats fingers much more readily than the "blower" side ... trust me, I know...

+1
That's because when you touch the suction side, the blades are going towards "pulling in" your fingers. On the blower side, they push everything outwards, so when you put your finger there, the blades just try to ride over it - hence why you can't get injured.

I would be more worried about breaking your fingers You can replace fan, but finger…

Broken fingers?! What kind of fans are you using?