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Mega-minireview: Vornado 633 "whole room air circulator"

Everything goes... within reason!

Fourth harmonic investigation

Postby LongRunner » January 19th, 2020, 10:12 am

On the 633, I count 32 flow-focussing vanes; the intake has 64 slats in the outer section and 36 in the inner part, and all three numbers are multiples of 4. (Removing the grille also gets rid of the fourth harmonic.) The 533 (which doesn't produce a noticeable fourth harmonic) has 25 flow-focussing vanes, 51 slats in the outer section of the intake, and 28 in the inner part; none of which share a common factor (other than 1).

If anyone reading this happens to have other Vornado models, it would be nice to respond with the number of vanes/slats (or photos in which all are visible) in them, and the audibility of any harmonic of the rotation (beside that expected from the blade count).

The DC models have made their way to Australia in the meantime, so I'll notify you if I get one.
Information is far more fragile than the HDDs it's stored on. Being an afterthought is no excuse for a bad product.

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6303DC impressions

Postby LongRunner » December 17th, 2021, 3:30 am

I was tossing up among which of the DC models to get; ultimately I got a 6303DC, the latest generation (also includes the smaller 5303DC and pedestal 6803DC).

Operation
Tonality is even better-suppressed than before; both the rear and front grilles now have 38 vanes, so no fourth harmonic instability.
Even at maximum speed (99), it now sounds quite smooth.

Minimum speed is lower than on the 633, but could be lower still.

Motor
It's 8-pole, 3-phase for smooth running (like HDD spindle motors) with PWM control, made by Delta with dual NMB 608ZZ ball bearings. Two lines of ID:
MO3-0217-07
MH08824PD-S3006
There are 5 wires; one white (unused) and the others as usual for Delta (black ground, red +24V, blue frequency output and yellow speed control).

One annoyance is that although the manual says the blades can be removed for cleaning, here they've put red threadlocker on the nut :silly:.
It is for this reason that I couldn't examine the motor driving circuitry.

PSU
While the 6803DC (pedestal) still uses an external power-brick, the 5303DC and 6303DC build it into the unit.
It's a bog-standard flyback SMPS, driven by a TOPSwitch-JX (going by the package and pinout; can't reach the clamp screw to reveal which variant) with the +24V output rectified by an MBR20200CT with insulated tab. No PFC, no MOV, though at least the NTC thermistor is present (but unsleeved).
Soldering mess.jpg
Could be worse I suppose, but it's quite bad enough (especially being before the fuse).
Soldering mess.jpg (266.23 KiB) Viewed 13499 times
Mess 2.jpg
Mess 2.jpg (181.03 KiB) Viewed 13499 times
There's quite a mess of flux where the cord wires are soldered in (and a bit at the junction of the two Y1 capacitors), so I cleaned that up after taking these.

On that note, being somewhat heavier, the cord is H05VVH2-F rather than H03VVH2-F. The air accelerator now doubles as a storage place for slack.

Controller
An LCM08F18GT20 is used, powered through a 78M05. Oddly, the PWM signal is low-pass filtered into a continuous voltage.

Capacitors
No joy; the main output caps are Xunda TM series (replace with Chemi-Con KYB), the rest are "SWC" KM series (probably general-purpose, I suggest replacing with something better for longer endurance). At least the output capacitors have a sufficient ripple current rating for the task (≈1.6A RMS for about 2A output at most, and actually doubled given that they are two in parallel with no coil between them), so it's not outright suicidal.

General build quality
About the same as before (fairly solid but with the occasional over-tightened screw), although at least with no knob to break.

Conclusion
The design in general is nice, but for the price only quality capacitors should be used.
As such, it comes close but ultimately falls a bit short of winning an award; good caps and clean soldering would raise it to Bronze.

UPDATE 2022-05-05: I recapped it using KYB on the PSU output, a KXG primary (which I put neutral-cure silicone under as with the original), Rubycon YXM for the 47/50 in both the PSU and control board (so all PSU caps now have 10k-hour endurance), a Panasonic FR for the 470 on the control board (although uncritical being after the 78M05), and ceramics for the 47/16 (although only operated at +5V) on the display/± button board.
I even replaced the Tenta X2 cap with an Epcos/TDK one for good measure.

Grades
  • Airflow: A. (Perhaps an incremental improvement from before, but nothing radical)
  • Noise: A−. Almost perfectly broadband (a superb result with uniformly sized and spaced blades), but I'd like minimum speed to match or undercut the sound level at least of a Barracuda ATA IV (it's only been 20 years since then :mrgreen:); as it stands, it's still much louder than that.
    (The motor itself is actually perfectly capable of going much slower; the limit being imposed by the microcontroller program.)
  • Appearance: B−. It's glossy, but at least being white mitigates that; and unlike some manufacturers, they actually remembered to peel the protective film off the LED display inside (either that, or it wasn't applied in the first place).
  • Build quality: B− again. Not bad overall, but for AU$349 I want to see nothing short of excellent. At least the warranty is decently long (10 years in their native USA, 5 years in Australia although that should rather be the minimum for a premium appliance like this).
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