Does your 420E suck in air through the phone (data) jack? :o

[ozij]

Because - as I discovered to my utter amazement yesterday - mine does!

I was changing filters yesterday, and had a problem I often have: a whistling sound in the air inlet area. Sometimes resettling the filters helps. I was fussing around with the filters (machine running) and suddenly, when one of my fingers was near the data jack (where you insert the data cable) the sound changed. Edit: and I could feel the air blowing near my finger.

Put my finger on the jack to plug it - no more whistling, and different sound. Finger off - whistle.

Whew.... So I stuck a phone cable in the jack for the night - and my machine was quieter than ever - and I couldn't fall asleep for wondering how it is on other machines! Amazing.

I'd be very grateful if 420E users would run this little check and report: just plug the jack with your finger, and let me know what happens.

Thanks
O.

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[Goofproof]

You keep your house too clean, the dirt that's pulled into the hole is supposed to plug it up.

In a Resmed, that's called the O2 Port, It's there to make sure the cord connector has enough O2 to burn. Jim

Duct Tape Time!

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[Snoredog]

Just checked mine, I keep the modular cord plugged in all the time, never noticed it doing that, but I unplugged it and turned it on wearing the mask, mine doesn't appear to do that.

I bought this new one about June of 2007, so it is one of the newer models (compared to my first 420's).

This one has been quieter than the first ones I've owned from day one, it is even quieter than my A-Flex.

[ozij]

Thanks, Snoredog. Edit: Do you mean "doesn't whistle" or do you mean "doesn't pull air in through the jack?" I suppose it can do one without the other (which is why I edited the original post too...).

Great idea, Goofproof!

O.

[tangents]

Ozij,

I'll have to wait until tonight to check mine. I also leave my data cord attached all the time, but still my machine whistles more than I'd like. If I can get rid of that - I'll be Sooooo happy!! Nothing I've done to the hose outlets has made any difference. This is going to drive me crazy all day now!

[TXKajun]

OK, now ya'll got me wondering, too! And I'm at work, so I gots to wait till this afternoon to check. Thanks a lot! LOLOL

Kajun

[-SWS]

Does your 420E suck in air through the phone (data) jack?

O, I experimentally set my 420e up at a straight pressure of 20.0 cm. Even at those pressures I couldn't detect any sound or air movement at the machine's RJ11 jack.

As a rule of thumb, those little RJ11 phone jacks are known to occasionally act up. Our little phone jack in the wall, for instance, periodically sucks in way more money than we think it should.


P.S. Might not be a bad idea to make sure your filters aren't clogged.

[ozij]

[quote="-SWS"]
P.S. Might not be a bad idea to make sure your filters aren't clogged.

[rested gal]

Well, how interesting, ozij.

Of course that made me start up my little 420E a few minutes ago. I'm not sure how old this particular one is... I bought it from Wader a couple of years ago. He had had it a year, I believe. It's extremely quiet -- unlike my first one which had a whining motor up/down sound all the time.

So... on to the experiment.

Whether the 420E was a foot or two away from me or with back of machine inches from my ear, I couldn't hear any difference in sound whether the phone jack was in it or not. But, as I said, I was lucky in that this particular 420E is a very quiet one anyway. No whine, no whistle. No odd sounds.

So... I tried something else.

If I put the back of my finger almost against the open (not plugged) phone jack, there was no sensation of air flow coming or going out of the jack while I breathed normally with my mask.

But... there was a slightly cooler feel on the back of my finger (near the open phone jack) each time I exhaled. I couldn't feel air movement, but the sensation of cooler temperature on the back of my finger when exhaling made me think, "Hmmm, there's gotta be a bit of air getting pushed out the phone jack when I exhale." Or... "Am I imagining the cooler feel?"

So...

I cut a strip of Kleenex almost the same width as the phone jack. Then separated the two layers of the Kleenex so that I had just one very thin strip. Taped the top of the strip above the open jack, hanging straight down over it...not against it.

If I exhaled lightly, the tissue barely moved. If I did a little stronger exhalation, the strip moved away more. If I did a strong huffing type of exhalation into my mask, the tissue at the phone jack got puffed away a lot. Every time.

There was no movement of the tissue when I inhaled. Not that I could see, anyway. It didn't get sucked toward the phone jack or move at all during inhalation.

Interestingly, it was only during the start of each exhalation that the tissue strip moved at all. As the exhalation proceeded, the tissue resumed a straight down position and didn't seem to move.

Which made me think of this:

While watching the pressure the 420E was using (which shows in the LCD window on the machine while machine is in use) the pressure always dropped (my edited correction -- the pressure went UP (not down) -- just as ozij described) a half cm when I did a huffing strong exhalation. Doesn't show any "cm drop" (edited correction rise) with my normal, rather light, exhalations.

Given the fact that the tissure moved slightly even with light exhalations, the pressure probably is dropping a tad each time we exhale. (edited to add this thought) A rise in pressure on the LCD may reflect the machine compensating for a sudden forceful exhalation. The light exhalations are just not dropping it enough to register a drop (edit: I should have said "compensatory rise", not "drop") on the LCD display. Perhaps it requires a whole half-cm drop to show there. (edited: There was no drop in pressure shown on the LCD...it was a rise of a half cm for a very forceful start to an exhalation.}

You remember how I've said that when I tried out resmed's EPR set at 3, for a three cm drop for exhaling, EPR always felt to me like there was resistance when starting to breathe out? That it was only as the exhalation progressed that EPR seemed to finally reach the drop it was set for? And, that it felt easier for me to get an exhalation started with the 420E than with a machine using EPR, even though the 420E doesn't have a feature that can be turned on for exhalation pressure relief?

I wonder now if that bit of pressure relief the 420E gives at the START of an exhalation (the moment when it's most useful to have relief, imho) might be related to the slight escape of air through the phone jack of the 420E when exhaling.

I've never had any problem exhaling when using either of my 420E's. That slight escape of air through the phone jack doesn't seem to affect the "set" pressure more than a half cm of drop (edited: it wasn't a drop, it was a rise in pressure shown on the LCD even with the most forceful exhalation start I could muster. Interesting.

My edits above are in red. ozij was correct about the pressure showing a half cm rise on the LCD, instead of a half cm drop, as I had originally written. Geeze, I sat there huffing and puffing, watching it go UP from 10 cm to 10.5 cm -- and then called that a "drop"! LOL!!

Good grief..a "drop" (that probably was a drop but gets machine-compensated into becoming a rise).... that's what my 420E was doing!!! Comfortable little rascal, any which way I exhale.

[ozij]

I replicated your Kleenex test (GREAT idea, that Kleenex strip).

Maskless, the machine almost swallowed the little piece.
With my mask on my face, it was waving boldly in and out each time I inhaled and exhaled. And this is at a pressure of 7.

While watching the pressure the 420E was using (which shows in the LCD window on the machine while machine is in use) the pressure always dropped a half cm when I did a huffing strong exhalation. Doesn't show any "cm drop" with my normal, rather light, exhalations.

Even weirder: When I huffed and puffed, the behaviour was the opposite: A strong (somewhat abrupt) exhale drove the pressure up a strong (somewhat abrupt) inhale drove it down. I can get that Kleenex waving out on exhale even with the plug in the socket - but it won't wave in as much.



O.

[-SWS]

Gotta love the plurality of opinions in this forum. Between Goofproofs' "your house it too clean" and -SWS's "make sure you filters aren't clogged....

Opinion? When I removed my two 420e filters to peer inside I discovered a neatly folded 8 1/2" by 11" sheet of paper. When I unfolded that slightly parched paper it read:

"Consumer Notice:
Congratulations on making it this far in the PB420e troubleshooting process! We issue this subtle reminder to never buy used filters. Used filters frequently arrive at our factory-authorized repair center pre-clogged with highly questionable particulate matter. Our own materials processing employees wearing HAZMAT suits even try to avoid touching previously-owned filters at all costs. Have a nice day!

Sincerely,
Your Highly Devoted PB420 Design Team"


Wish I could have taken credit for that clogged-filter idea...

[gasp]

Well, how interesting, ozij.

Of course that made me start up my little 420E a few minutes ago. I'm not sure how old this particular one is... I bought it from Wader a couple of years ago. He had had it a year, I believe. It's extremely quiet -- unlike my first one which had a whining motor up/down sound all the time.

So... on to the experiment.

I love how your mind works : ) I almost wish I had a 420 just to experiment!
: )))

[DreamStalker]

So what you all have discovered is that the 420e has a mechanical exhalation relief via the phone jack?

[-SWS]

Any design team clever enough to exploit the air intake for consumer notices just may be clever enough to exploit the phone-jack toward exhalation relief.

Seriously, though, I'm surprised the end-to-end air delivery path is not better sealed. I don't think DSM has internal pictures of this model posted on his web site yet.

[ozij]

I think I've discovered a source of unfiltered air entering my machine...

And DSM's site has This section temporarily unavailable where he had the decontruscted machines... (He had a 420S I think).
O.