Author Topic: What resistor ohm will work better to repair this waterpik?  (Read 590 times)

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Offline artvandalaiTopic starter

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What resistor ohm will work better to repair this waterpik?
« on: January 05, 2025, 09:57:38 pm »
The resistor on this waterpik blew. I changed it with the a similar spec 47ohm 2 watt yageo resistor but it still keeps blowing the resistor. Checking with the multimeter the motor, capacitor, diodes, and thermal fuse all checked normal. Will a higher ohm resistor work better? What ohm resistor will work better to repair this waterpik? This video is showing the repair with a 56 ohm resistor
« Last Edit: January 05, 2025, 10:05:17 pm by artvandalai »
 

Offline fzabkar

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #1 on: January 05, 2025, 11:29:27 pm »
Was the original resistor a fusible safety type?

https://www.digikey.com/en/product-highlight/y/yageo/fusible-through-hole-resistors

I suspect that there may be carbon dust between the commutator segments. Can the motor be disassembled?
 

Offline Simmed

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #2 on: January 05, 2025, 11:51:31 pm »
use 2x 100R
or   3x 150R
spread the power
V=I.R  Q=h.A.(dT) q=(dT).p  Q=C.V  F=m.a  F=q.v.B.(sinθ)
 

Offline DavidAlfa

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #3 on: January 06, 2025, 12:07:18 am »
Maybe something is wrong in the mechanical part, overloading the motor?
« Last Edit: January 06, 2025, 12:09:09 am by DavidAlfa »
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Offline fzabkar

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #4 on: January 06, 2025, 08:02:20 am »
Teardown:

https://newscrewdriver.com/2022/07/11/waterpik-wp-150w-teardown/

New motor (DF315XLG) for ~US$10:

https://www.aliexpress.com/item/1005005779645234.html

Rating of Waterpik is 120V, 16.4W.

Current draw is ...

  I = 16.4 W / 120 V = 0.137 A

Dissipation in resistor is ...

  P = I^2 x 47 ohms = 0.88W

« Last Edit: January 06, 2025, 08:14:43 am by fzabkar »
 

Offline Gyro

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #5 on: January 06, 2025, 10:02:20 am »
Was the original resistor a fusible safety type?

https://www.digikey.com/en/product-highlight/y/yageo/fusible-through-hole-resistors

I suspect that there may be carbon dust between the commutator segments. Can the motor be disassembled?

Yes, it's a fusible type, as clarified in the OP's previous thread on this... https://www.eevblog.com/forum/beginners/what-type-of-resistor-material-and-tolerance-should-i-use/

For it to keep failing, something must be overloading it (the motor). It's failing for a good (safety) reason.
« Last Edit: January 06, 2025, 10:06:07 am by Gyro »
Best Regards, Chris
 

Offline artvandalaiTopic starter

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #6 on: January 06, 2025, 01:13:28 pm »
https://www.digikey.com/en/products/detail/yageo/KNP200JB-73-47R/9119797

I purchased these Yageo resistors. I didnt notice any black dust from worn motor brush. It was purchased new and only used a handful of times. 
 

Offline artvandalaiTopic starter

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #7 on: January 06, 2025, 01:30:48 pm »
Im hoping its not the motor, the most expensive part to replace as this waterpik is for resale instead of throwing it out.
 

Offline Gyro

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #8 on: January 06, 2025, 09:31:00 pm »
If it's had so little use, I would return it under warranty, something in the motor/pump/pipework sounds defective. Resale, with or without the correct safety resistor fitted, sounds like a headache in the making.
Best Regards, Chris
 

Offline artvandalaiTopic starter

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #9 on: January 06, 2025, 09:38:07 pm »
Thanks, its been two years since i bought this item. ive been holding it hoping to fix it. Wouldnt a higher ohm resistor as the video linked shows fix the problem from higher resistance from wear?
 

Offline Gyro

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #10 on: January 06, 2025, 10:15:51 pm »
That's a shame.

A higher value resistor will actually drop more voltage and so dissipate more heat if the motor is overloaded, so will fail quicker. What he's done in the video is to replace the 0.47R resistor with a much larger body non-fusible 0.56R resistor. Great for persuading the motor to spin again but throwing the overload protection of the original design out of the window. Using a slightly lower value fusible resistor would work if the design is marginal, but it really should work as designed, including staying safe.
Best Regards, Chris
 

Offline fzabkar

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #11 on: January 06, 2025, 10:33:15 pm »
If you remove the motor, does the shaft rotate freely? Can you turn the geared mechanism freely?
 

Offline cruff

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Re: What resistor ohm will work better to repair this waterpik?
« Reply #12 on: January 09, 2025, 02:34:51 am »
Is there also discoloration on the trace leading from the + terminal of the capacitor, or is that a lighting issue. Have you checked to see if that cap has a problem?
 


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