Inductor Question

[H2814D]

Hi all. I'm working on a US Model 220vac Hot Tub Water Pump that runs 24/7. They last a couple of years and then they just die. I decided to open one up and see what was inside it. According to the information I have read about this thing so far, there are no moving parts, except a magnetically spun impeller which seems to float in a housing on the other side of the pump from the electronics. Anyway, I have removed and tested all of the most common suspect parts (E-Caps- 68 uF 400V, N Channel Mosfet- 11N60, that fuse) and they test out fine.

When I looked at the Inductor (150 uH), though, I noticed it appeared to have expanded slightly and had broken the plastic casing on one side, the side that was not glued to the PCB. From the top, it appeared to have four legs soldered to the PCB. I did a continuity check of each leg and discovered both legs on one side of the component were not connected together (I mean bridged), and Ohm'd out to about 2.9 kOhms on each side. If I remember correctly now, going diagonally across the Inductor to each leg, I got .1 Ohm. And from one side across to the other, nothing. So it seems like there are two coils in this Inductor. Does that sound right?

When I search for a replacement part, I am only finding 150 uH Inductors, that look like this one, but have both legs on each side connected together, but I specifically remember having to remove four legs of the Inductor from the four pads. The solder was some kind of super glue solder, and it was necessary for me to almost destroy the bottom of it to get it off the board. A very hot soldering iron was necessary. That, and the glue they used, made removal a chore.

So my question are, are there Inductors with two coils in them, and can anyone identify the replacement part number for me please? And then this one. Which component would be the most likely suspect to just fail after a couple years of constant running? Would that Inductor be one of them? I need to find one and replace it anyway, but I was just wondering, in the meantime.
Thanks in advance.

 

[Delta Prime]

Hello there welcome to Maker Pro.
I could help you better if you could provide me with the make and model of your hot tub water pump.
Oops sorry is that big wheel the make and model? I'm kind of new at this.

 

[Bluejets]

So my question are, are there Inductors with two coils in them, and can anyone identify the replacement part number for me please? And then this one. Which component would be the most likely suspect to just fail after a couple years of constant running? Would that Inductor be one of them? I need to find one and replace it anyway, but I was just wondering, in the meantime.

Without any circuit information, which I imagine would be non-existent, it is a rather big ask short of "reverse engineering" the whole shebang.
I for one, wouldn't bother given life is short and replacement most likely available at less cost than any parts/labour.

 

[kellys_eye]

Got any more details of the 3n3 capacitors 'bundled together'? They remind me of a particular version of capacitor well known for their ability to self-destruct.

 

[Delta Prime]

Don't you worry I'm on it kiddo!
Is this your pump?

So my question are, are there Inductors with two coils in them

Yes there are inductors with two coils in some have many more coils in them.the coil with the markings 151 I would replace because of your description and your curiosity try googling coilcraft they have good tutorials and may be able to purchase that inductor. And yes the 3N3 capacitors are cheapos! As long as you're messing around in there go ahead and check those diodes out of circuit!
If It was me and I purchased these things once every year I'd have a closet full of them spare parts! and then jump back in my hot tub. Where I make my own bubbles!!
By the way 151 is the police code when they speak in to their walkie talkies for crazy person.

 

[Ylli]

The inductor, along with the MOSFET likely for an oscillator driving the 'impeller'. Really curious as to how power is coupled to that impeller - Any pictures of the back of the board or o the cavity of the pump after the board is removed?

 

[H2814D]

I could help you better if you could provide me with the make and model of your hot tub water pump.

Thanks, Delta. That's why I photographed the end cap with the make and model number. I'm surprised, however, you didn't have your crystal ball figure it out for you.

Is this your pump?

Yep. The electronics appear to be the same. The housing is a bit different though.

 

[H2814D]

Without any circuit information, which I imagine would be non-existent, it is a rather big ask short of "reverse engineering" the whole shebang.
I for one, wouldn't bother given life is short and replacement most likely available at less cost than any parts/labour.

Not necessarily the cost of a replacement I am working with, but the challenge to fix it. I'm doing the work. And MY time is cheap.

 

[Minder]

Appears to me to be a typical AC ECM (electronically commutated.) 3ph motor, the same technology used in HVAC variable speed fans etc.
These are also 1ph fed.

 

[H2814D]

Got any more details of the 3n3 capacitors 'bundled together'? They remind me of a particular version of capacitor well known for their ability to self-destruct.

There doesn't appear to be any visible indication of failure. Here is a pic of one side of one of them. All three are the same.

 

[H2814D]

The inductor, along with the MOSFET likely for an oscillator driving the 'impeller'. Really curious as to how power is coupled to that impeller - Any pictures of the back of the board or o the cavity of the pump after the board is removed?

Are you saying that those two components are my likely failure points? The 11n60 MOSFET checks out fine, out of circuit, with a simple MOSFET testing procedure. I don't know which component on that board would be an oscillator though. Here is a picture of the back of the PCB.

Really curious as to how power is coupled to that impeller

You can see the entire pump in Delta's post above. ^^^^
Attached are pictures of the different sandwiched components that make that impeller spin. According to the manufacturer, the only moving part is the part with the impeller mounted to it, and it is not serviceable...all one sealed piece, except for the outer metal ring. Under that metal dome (space ship looking thing ) is a magnet. It is quite strong and there is quite the magnetic pull when the dome is inserted into the cup it fits into.

The dome and the impeller are attached and move with each other. The outer steel ring around the outside of the dome sets in the plastic housing and centers the impeller assembly. When the impeller and dome are fitted together into the mating piece, the inside of the dome rests on a ceramic ball and sort of "floats" the impeller. So when it is in operation, I am guessing there is a magnetic field generated inside the larger middle housing, and that, in turn spins that impeller.

The cup the impeller assembly fits into is not magnetized when not powered. I don't know if it is when the electronics are working correctly. I would guess it would be something similar to any electric motor, the only difference is there is a complete separation of the components to allow the impeller to be in water and the rest of it to not be.

 

[H2814D]

I think I may have found the Inductor I am looking for. What do you guys think? It is a "Coupled Inductor."

https://www.mouser.com/datasheet/2/445/744870151-3095988.pdf

It appears this one has a "W" before the 151 though. Mine doesn't. It is made by Wurth Electronics, so that just may be the way they mark theirs. 150uH and the dimensions and tab locations are exactly like my original.

 

[Minder]

It appears to be standard common-mode choke configuration?

 

[H2814D]

It appears to be standard common-mode choke configuration?

The one I am trying to replace, or the one I provided the datasheet for?

 

[H2814D]

The inductor, along with the MOSFET likely for an oscillator driving the 'impeller'. Really curious as to how power is coupled to that impeller - Any pictures of the back of the board or o the cavity of the pump after the board is removed?

In the approximate middle of the PCB are three open pin connections. On the main part of the metal part of the pump housing, there are three pins that exit the back of the housing. Those pins come through the PCB when everything is put together and then the pins are soldered to the PCB. That IC is thermal glued to the housing as well. Took me a while to figure that out, during disassembly.

 

[Bluejets]

Really curious as to how power is coupled to that impeller

Magnetic drive, common in small water pumps.

 

[Bluejets]

Not necessarily the cost of a replacement I am working with, but the challenge to fix it. I'm doing the work. And MY time is cheap.

Good luck.

 

[H2814D]

So I realize it has been a while, but I work on these things when I want to, not because I have to. In this case, I replaced the 151 Coupled Inductor after finding it with what appears to be an expansion crack/split on one side of it. And because of kellys_eye post above, about his suggestion about the problems with those type of caps (WIMA's) known for failure, I replaced those as well. The caps were hard to find. I actually had to get them from an Ebay seller in Taiwan, so that took a while. The Inductors were sourced through that "A"-"express" site in China. They sent me 8x8's (mm) the first time and then the correct 12x12's after letting them know they made a mistake. That contributed to the wasted time waiting for them. The original caps tested OK out of circuit. In any case, the pump is back in operation after the replacements. It may have just been the inductor, or it may have been a combination, but it is working now. I have a video, but I don't know how to attach it here. So thanks, all, for your help. I wanted to let everyone know of the success, however short-lived it may be, based on the reputation of these pumps. Oh yea. I have extra parts, if anyone needs one worked on.

 

[H2814D]

So I was also given an almost identical additional spa pump, this one had "Laing" as the brand and E-14 as the Model Number. The Laing PCB was almost the same as the other one with Goulds, however this PCB had different WIMA Caps in it. This one had two 1n0's, and one 2n2. The same Inductor value (150uH) was used on both. I ordered the different caps and used one of the recently purchased Inductors I already had, because I had ordered more than one of them. Replacing these same components on the Laing E-14 resulted in a successful repair of the second pump. So it looks like the Laing E-14 and the Goulds E-14 Spa Pump can be repaired by replacing the caps and the inductor. And actually, likely just the Inductor, based on my subsequent testing.

The Goulds Inductor (the reason for this thread) was cracked and expanded when I opened it up. I damaged it when I removed it from the PCB, due to a strong adhesive used to secure it to the board. The Laing inductor did not have any visual signs of failure prior to removal, but I was a bit more careful when removing it with the hopes I could actually get some ohm values off of the windings later. I wanted to compare them to the new Inductors I had purchased. The removal was successful and I was able to get good tests off of the old component contacts. In the pictures, the old Inductor is on the left and the new one is on the right. See the pics. You can see the different values on the meter for the same test points on both the old and the new. So based on that, I'm pretty sure the Inductor failed and was the cause of the pump failure.

Now for the questions I have for you. This pump runs all the time and is never shut off. It is simply a recirculation pump for a spa. Based on your expertise, what is it that would cause this particular Inductor to fail in these motors? I understand it to just be a coil of wire, or two coils in this type of Coupled Inductor, I suppose. Is it normal for an Inductor to just "wear out?" Thanks in advance for any answers.

By the way, the pics make the two larger E-Caps to appear bulged, however, they are not and read fine, both ESR and uH on the meter.

 

[Delta Prime]

I understand it to just be a coil of wire, or two coils in this type of Coupled Inductor, I suppose. Is it normal for an Inductor to just "wear out?" Thanks in advance for any answers.

You're welcome,prematurely.
Simple! !t's the engineering.
Selection of components. That's why they're cheap(Inexpensive)you can buy a couple of them and mass a collection for spare parts. For the DIY kind of guy and feel good about yourself when you solved the mystery.
Now get back in that hot tub or I'm going too...