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Old 09-29-2021, 09:26 PM   #1
momaka
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Default Aquarius WaterPik WP-100W water flosser

And for today’s “Other Weird Devices” thread, let’s have a look at an Aquarius WaterPik WP-100W water flosser. What is it? Apparently, it’s kind of a power washer, of sorts, for cleaning teeth & gums. Who knew these existed, right?

A family friend asked me to take a look at their older one, since it stopped powering On. So let’s have a look at what went wrong.

First, a view of the box (note: it’s from a newer model) and the device itself:

^ Is it me, or does anyone else find it a little humorous how the box says it’s “ADA Accepted”? I’m not here to try to sink the reputation of this product… buy to me at least, the wording makes it sound as if this device probably doesn’t have many benefits for your teeth/gums (or at least not any more than regular toothbrush, despite the box claiming otherwise.) On the other hand, it also probably doesn’t hurt anything in any way… hence the “Accepted” instead of “Approved” label. But anyways, let’s move on…

A few pictures of the device itself:




Label with model number info:


Now for the fun part: tare it open. OK, I didn’t quite “tear” it. Instead, all that is needed here is to remove 2 screws holding the “pressure hose” and then 4 more screws from the bottom of the case. However, this still won’t allow the bottom cover to come off. Once all of the screws are removed, pulling force has to be asserted onto the bottom cover, after which there are 4 small rubber feet that need to be pushed in with a small screwdriver to separate the pump base assembly from the bottom cover. The result is this:

Bottom cover:
Aquarius WaterPik WP-100W water flosser (7).jpg

With the bottom cover off, next step is to take out the pump base assembly and electronics from the top case. To do that, the water flow knob needs to be removed by prying it from the shaft from inside the case. Once that is off, everything should come apart easily.

Top case/cover:
Aquarius WaterPik WP-100W water flosser (5).jpg
Aquarius WaterPik WP-100W water flosser (6).jpg

Pump base + electronics:






Motor info: it’s a Johnson Electric, model DF315XLG, rated for 120V DC.
Aquarius WaterPik WP-100W water flosser (11).jpg

^ It’s good to see a quality brand motor used here… though, for the $80-100 that these flosser devices cost, I think that leaves a little more to be desired for the quality of the rest of the device. The pump and gears, for example, are all plastic.

Moving onto the circuit board - there’s not much to it: four diodes for a full-bridge rectifier, an electrolytic cap for filtering the rectified DC, and a fusible MOX resistor in series with the Neutral line. Live is connected to a 3 Amp, 125VAC switch before going into the circuit board.


The 4 diodes are regular 1N4004 silicon parts (1 Amp, 400V) and the MOX resistor measures around 47 Ohms (actual reading: 48.5 Ohms.) I think it’s rated for either 1 or 2 Watts. I couldn’t figure out the rated resistance from the color bands due to burn-in on the coating. It looks like the resistor was pushed a bit too hard.

Since this is BCN, below is an image of the electrolytic cap.
Aquarius WaterPik WP-100W water flosser (13).jpg

In case the picture isn’t clear… brand is “KOME” (series: “TY”) and the cap is rated for 250V, 100 uF, and 105°C. I didn’t bother looking up a datasheet for it, as it’s probably cheap Chinese GP stuff. But for filtering rectified line DC, it probably doesn’t matter too much.

And finally, here’s why the device wasn’t working:
Aquarius WaterPik WP-100W water flosser (14).jpg

Aquarius WaterPik WP-100W water flosser (15).jpg

TCO (thermal cutout) was open. It’s a Panasonic/Matsushita EYP2BN109. Not sure if it had operated before (and how many times.) But having a rated functioning temperature of up to 114°C, I think it would have been visible if anything (including the TCO itself) ran that hot. So I’m not sure what caused it to fail (perhaps improper soldering temperature, or perhaps just not adequate enough to handle the power requirements of this device?) I checked the power draw of the flosser by temporarily jumping across the TCO with a piece of wire, and the flosser didn’t draw more than 15 Watts on my K-A-W meter while operating. So the rating on the label is accurate, which means the running current isn’t high. And on that note, the motor didn’t get too warm either for the 1 minute or so I had it running while emptying a full tank of water. The only thing that seemed to run hot was the R1 resistor. In fact, that yellowing of the plastic seen on the top case/cover is right where R1 is. Doing some basic calculations… with 120V AC and 15 Watts of power draw, the flosser should be drawing about 0.125 Amps from the wall. By I^2R losses, that makes R1 dissipation around 0.75 Watts… which seems about right to make it run hot if it’s rated for 1 or 2 Watts (I’m guessing probably 1 Watt.)

So it looks like the TCO is really the only part that went bad here. Everything else seems to be functioning OK. I wonder if I should find a different TCO replacement, though (well, I will have to, as the EYP series TCOs from Matsushita/Panasonic are discontinued now.) And on that note, I wonder why they have the TCO right on the motor. Is this the part that is expected to run the hottest if the device is left On for an extended period of time? Granted that’s where all the power is going into the device, it makes sense, I suppose. But then why use a TCO rated for 114°C? Shouldn’t the rating be a little lower? I feel the plastic base holding the motor would melt if anything got that hot. Moreover, I don’t like the fact that the TCO is held onto the motor with just tape and that there is only 1 layer of tape insulation, separating one lead of the TCO (that carries positive rectified DC voltage) from the motor’s case.
Aquarius WaterPik WP-100W water flosser (16).jpg

At high temperature, they really are counting on the tape to not melt here (unless the tape is special… though it doesn’t look like it.) Even so, I feel a bit uneasy here about the electrical insulation, despite the UL certification.

On a related note, I wonder if R1 will/should burn out first before the TCO, seeing how hot it seems to have been running. Also, I don’t see a fuse anywhere. I know R1 should act as one in the event the “bridge rectifier” goes bad or the electrolytic cap goes shorted… but is that good practice? R1 is on the Neutral, and there is nothing to disconnect the Live in case of failure. So perhaps it would be a good idea to add a series fuse to the Live while at it? (1 Amp, 250V??)

Lastly, a warning to anyone trying to service one of these flossers: if the TCO goes bad (open), like in my case, this can leave the electrolytic cap fully charged to ~160V DC. What’s worse is that there is conformal coating on the PCB. So when I went to check if the cap was charged before touching anything in there, I was mislead to believe that it wad discharged due to not getting any reading on my multimeter simply due to the multimeter’s leads not being able to make good contact with the solder on the PCB from the conformal coating. It wasn’t until I accidentally touched both the (+) lead on the motor and the cap’s case (vent) that I felt slight “tingles”, realizing something wasn’t quite right. Luckily (or not? ) this happened before I tried testing the diodes with my multimeter. I imagine a cheap meter could easily get zapped by the energy stored in the cap… or worse, if you happen to run that potential across your body. So do beware that this could be a shock hazard if the TCO is open. There is no discharge resistor across the cap.

Anyways… off to finding a replacement TCO now, I suppose.

Last edited by momaka; 09-29-2021 at 09:30 PM..
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Old 09-29-2021, 10:32 PM   #2
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Default Re: Aquarius WaterPik WP-100W water flosser

Very interesting product but what I do not understand why have a small motor running at such high voltage

Why not have a 24 volt motor and a small switching-or-transformer type of power supply
I would think that this would be safer in the long run

Like you I do not understand why they would have used a thermo fuse what would get that hot
But I have seen them used for current control device so may be why they used one
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9 PC LCD Monitor
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30 Desk Top Switching Power Supply
10 Battery Charger Switching Power Supply for Power Tool
6 18v Lithium Battery Power Boards for Tool Battery Packs
1 XBox 360 Switching Power Supply and M Board
25 Servo Drives 220/460 3 Phase
6 De-soldering Station Switching Power Supply 1 Power Supply
1 Dell Mother Board
15 Computer Power Supply
1 HP Printer Supply & Control Board * lighting finished it *


These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
2 Hem Saw Computer Stack Board

All of these had CAPs POOF
All of the mosfet that are taken out by bad caps

Last edited by sam_sam_sam; 09-29-2021 at 10:35 PM..
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Old 09-30-2021, 01:12 AM   #3
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Default Re: Aquarius WaterPik WP-100W water flosser

LOL I picked one up at a second hand store specifically to be used as a tiny power washer! Ever wonder how to clean a peanut butter jar? Well now you know!

Mine works but I thought it had a diaphragm pump in it, but now you made me curious about opening it and seeing how it pumps, now I'm thinking it's probably similar to this one...

Ultimately bean counter wins!
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Old 09-30-2021, 06:47 AM   #4
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Default Re: Aquarius WaterPik WP-100W water flosser

those have been around for many decades,
i didnt know they still made them though!
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Old 09-30-2021, 09:38 AM   #5
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Default Re: Aquarius WaterPik WP-100W water flosser

To be accurate, getting shocked by a charged capacitor (even photoflash) is nowhere near as bad as getting shocked by power mains...

... at least a capacitor shock is of limited joules of energy. Still can cause a jump, but power mains... you'll be lucky if you can jump away.
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Old 10-05-2021, 03:11 PM   #6
momaka
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Default Re: Aquarius WaterPik WP-100W water flosser

Well... I still haven't gotten a replacement TCO for this yet. Trying to see what other parts I might need before/if I do a Digikey or Mouser order.

That said, here's the two TCO's I'm looking at right now that I think might work:

1) OptiFuse K2B-110, rated for 2 Amps, 250V, and 110°C. (Digikey P/N 2298-K2B-110-ND)
https://www.digikey.com/en/products/...B-110/12170961

2) OptiFuse K2B-115, rated for 2 Amps, 250V, and 115°C. (Digikey P/N 2298-K2B-115-ND)
https://www.digikey.com/en/products/...B-115/12170885

I'm leaning towards #1, though. I doubt the 4° difference (lower) between it and the original TCO will matter that much. Both of these come in a radial box instead of axial case like the original TCO... but again, I doubt that can matter here too much. Just need to isolate the leads properly from the case of the motor, and all should be OK.

Quote:
Originally Posted by sam_sam_sam View Post
Very interesting product but what I do not understand why have a small motor running at such high voltage

Why not have a 24 volt motor and a small switching-or-transformer type of power supply
I would think that this would be safer in the long run
Probably due to costs. For a 24V or other lower voltage motor, an SMPS would surely be needed here, as a regular line-connected transformer would have to be very big (and expensive) for the amount of current needed at that lower voltage. And if this thing did use an SMPS, you can bet the caps in that would be the same no-name cheap stuff, so the device probably wouldn't last even past the warranty period. Not to mention higher costs to manufacture. So it makes sense that they went with a high/line voltage DC motor here - it has good torque and doesn't need a complex power supply. Those line-voltage DC motors are also relatively safe. I just don't like how they installed/insulated the thermal cutoff fuse on the case of the motor.

Quote:
Originally Posted by sam_sam_sam View Post
Like you I do not understand why they would have used a thermo fuse what would get that hot
Right?!
My logic tells me they should have used a higher current and lower temperature TCO... so that it can cut off the motor more frequently, but not suffer a premature death due to it being rated for higher current.

Quote:
Originally Posted by eccerr0r View Post
LOL I picked one up at a second hand store specifically to be used as a tiny power washer! Ever wonder how to clean a peanut butter jar? Well now you know!
LOL.
I guess for cleaning up weird-shaped objects where a sponge or brush can't reach, perhaps something like this flosser could be the right tool for the job. But for a peanut butter jar? - I'd rather just wash it with a sponge and regular dish soap. Will probably be quicker too... and less messy. When testing the flosser with the TCO bypassed, I noticed it splashed a lot of water everywhere in my kitchen sink and even a tiny bit on the kitchen window. I feel like this thing would make quite a mess if I tried to clean anything bigger and more open. Not to mention slower too. Will stick to my sponge and dish soap for the time being.

Quote:
Originally Posted by eccerr0r View Post
Mine works but I thought it had a diaphragm pump in it, but now you made me curious about opening it and seeing how it pumps, now I'm thinking it's probably similar to this one...
Meanwhile, before I had opened mine, I though these would have used a centrifugal-style pump - kind of like a regular pressure washer.

Alas, the pump used here - at least in the older unit I have - is piston-style pump. Yes, it's kind of like a small 1-cyl. gas engine... but made of plastic... which is why I don't think these products will last that long. It's only so many cycles that small piston can make before it wears down. And I imagine hard water (like we have here) will further accelerate that. But I guess we will see.

Quote:
Originally Posted by stj View Post
those have been around for many decades,
i didnt know they still made them though!
Looks to be the case indeed.

I was reading some reviews of Amazon, and many people in the reviews mentioned their older models lasted a lot longer than the newer ones. The new flossers don't have a hard switch like this unit, from what I can see on the pictures. Instead, they appear to have a "touch"-style On/Off button (or perhaps momentary push button?), along with another touch button to let you choose between "floss" and "massage" and an LED info panel. So by the looks of it, the newer flossers may have some kind of a power supply inside as well - i.e. certainly more complex circuit inside... so probably even more parts to fail, IMO. At least this older one is pretty straight-forward on the electronics side. Again, I just don't like the plastic pump and feel the insulation of the TCO is questionable. But apart from that, I take it these older flossers were indeed built better.

Quote:
Originally Posted by eccerr0r View Post
To be accurate, getting shocked by a charged capacitor (even photoflash) is nowhere near as bad as getting shocked by power mains...

... at least a capacitor shock is of limited joules of energy. Still can cause a jump, but power mains... you'll be lucky if you can jump away.
You also have to consider the fact that one source is DC, while the other is AC. While DC voltages can be more lethal, due to being able to pass directly through nerves... it also generally takes a slightly higher DC voltage to get a shock, since the body's skin has relatively high insulation to DC. But with AC, the skin partly acts like a capacitor, thus allowing higher currents to pass at much lower voltages. Hence why if you touch 50V DC, you may or may not feel anything... but with 50V AC, you certainly will. Of course, if you put probes through your skin or somehow bypass its insulation in any other way, then those 50V DC could actually become lethal. Meanwhile, 50V AC still may or may not be lethal, depending on the frequency - the higher the frequency, the higher the "skin" effect (i.e. current only able to flow through the top-most surface of the "conductor".) Thus, very high frequency AC actually may not go through any of the body's nerves to damage them.

So in relation to the charged cap in this flosser... yeah, it's of limited energy, and probably not much to worry about. I guess for those in Europe or elsewhere with 220/230/240V AC lines, that cap could pack a little more punch... though probably still nothing anywhere near lethal. Of course, it's just something to beware of. After all, it's the body's reaction to getting shocked that could be dangerous, especially if you are holding any sharp tools in your hands or have your hands near a sharp object and yank back due to reflexes - that can get you cut somewhere.
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