Attempt to repair a "non-repairable" shaving machine base

Thread Starter

PsySc0rpi0n

Joined Mar 4, 2014
1,744
Hello.
A few years ago (in 2017 iirc), I bought a Philips S9521 with a base called SmartClean.
This base has at least 2 functions. 1 is to clean the head of the shaver and the other is to dry the head after the cleaning. This drying function stopped working. So I took the base to a Philips dealer and they opened the base and I was told that there is a motor that stopped working and that this motor is no longer sold.

This motor is probably responsible to suck the cleaning liquid up to the head of the shaver, from the bottom of the base where the liquid container is.
I don't remember if this function was still working but I think it was, so when I was told the motor was bad, I "didn't buy it" right away.

So, when I got home, I decided to open the SmartClean and the first thing that popped to my eye sight was this:


This is some kind of inductor / heat element that is responsible for the rying function. I see 4 wires. 2 copper wires and 2 red coated copper wires. One of these red coated copper wires is cut short. I bet this is the cause of the heating / drying function not being working.

In this case, I need confirmation of more experienced people to tell me that this is the case and that if I am able to bridge that gap, that the heating element will work again.

About the motor, I'll check it when I fix this part because it might not work if the base is not fully assembled and the liquid container is not in place due to sensors sensing the absence of the liquid container!

Another picture:
 

Hymie

Joined Mar 30, 2018
1,274
I don’t think the photos are of the heating element, the enamel wires look more from the winding of a motor.

Given the alternating arrangement of the wires, the copper coloured wires may be un-enamelled with the enamel coating giving the other wire its colour (red), such that with the wires adjacent/touching each other, there is no short.

That said, it looks like the red wire at the top has broken away from the yellow insulated wire.

I’d re-make the connection and give it a try, as the whole thing is powered from 5V you are unlikely to create a hazard.
 

Thread Starter

PsySc0rpi0n

Joined Mar 4, 2014
1,744
Well, I don't want to dispute your knowledge but the area that that widing covers is literaly the area where the head of the shaver sits to be cleansed and dried. And when the device was working, that area could be sensed kinda hot by toutching it (from the outside, of course). And there is no motor next to that winding. There is a motor further down but it's enclosed in a dedicated housing and it is fed by two other wires.
 

Thread Starter

PsySc0rpi0n

Joined Mar 4, 2014
1,744
I tried to solder a wire to bridge that gap but it still didn't warmed up. There is also this motor with reference FK-180SH-10400 BD736624 that seems not to be working.

I removed this motor from the base and gave it external power from my power supply. I started like wit 15V, which is the voltage the transformer of the shaver uses (15V and 360mA) and limited current to 100mA. The power supply dropped the voltage to 3.49V and current raised to the limit (99mA).
Then I increased the current limit to 150mA but still the voltage drops to 5.2V and current sits at 150mA.
Another current limit increase up to 200mA and the voltage drops to 6.9V and current at 201mA.
Can I assume at this point that the motor is "dead"? Or should I raise te current limit to what is in the transformer, 360mA, and try again?
 

MrAl

Joined Jun 17, 2014
11,281
If it is the motor, sometimes you can pull one entire winding off one of the poles and still get it to work, strange as this sounds.
There has to be enough poles on the motor though maybe 4 or more I don't remember now.

I've fixed one motor this way. The strength of the motor decreases but it can still work if the load is not too great.
I fixed another motor by taking part of a winding off. That was in a microwave oven, the turntable motor. It was clear that the enamel had been eaten off of the outer most winding. Removing a couple layers (only) and the motor worked again for years after that.

Of course these fixes will not work for every motor, but you could take a look and do some measurements. If there is a shorted turn, you may be able to take that one winding off or take a few turns off or something like that and still get it to work. Note that in a fix where one complete winding is removed there will be a little more vibration caused by the mass distribution imbalance, which you can counter with a small weight if the vibration is too much.
 

Thread Starter

PsySc0rpi0n

Joined Mar 4, 2014
1,744
Those measurements suggest the motor is effectively a short-circuit. Likely a shorted turn.
Actually the motor is just fine! I removed a small rubber cap that was covering the axe of the motor and there was rust inside. The axe of the motor was stuck due to the rust. I removed the rust, slightly forced a few turns with the help of pliers and put some thin oil on this axe. Then applied the same 15V and current limited to 100mA and the motor was alive, consuming only around 30mA.

If it is the motor, sometimes you can pull one entire winding off one of the poles and still get it to work, strange as this sounds.
There has to be enough poles on the motor though maybe 4 or more I don't remember now.

I've fixed one motor this way. The strength of the motor decreases but it can still work if the load is not too great.
I fixed another motor by taking part of a winding off. That was in a microwave oven, the turntable motor. It was clear that the enamel had been eaten off of the outer most winding. Removing a couple layers (only) and the motor worked again for years after that.

Of course these fixes will not work for every motor, but you could take a look and do some measurements. If there is a shorted turn, you may be able to take that one winding off or take a few turns off or something like that and still get it to work. Note that in a fix where one complete winding is removed there will be a little more vibration caused by the mass distribution imbalance, which you can counter with a small weight if the vibration is too much.
Thank God, I don't have to do such thing! That wouldn't probably worth the value of a new motor! lol. At least in my case, no?

Can you give us a pic?

I would be looking for a smaller motor that you can adapt to fit in the space.
I already put the motor back in place.

However, anything is working yet! All functions seems to be dead. Or better, the control panel seems to be working. The buttons light up and change state after the expected time have passed, but there is no cleansing liquid being pulled up nor heating to dry the shaver head!

Tomorrow I'm going to take the board to my work where I have an USB microscope so that I can take reference of some components and try to figure out if are there any of them clearly needing replacement! I'l probably need help to figure it out too! I don't have enough experience to check all things in the board, for sure!
 

Thread Starter

PsySc0rpi0n

Joined Mar 4, 2014
1,744
There is a MOSFET that I tested. At least, I think this is a way to test MOSFETs on circuits.
This is an FDMS86252, N-channel PowerTrench MOSFET.

So, what I did was
1 - Test Drain-to-Source
2 - Test Drain-to-Gate.

1.a - DMM in diode mode and Black Probe on Drain, Red on Source
Reading: 0.4915V
1.b - DMM in diode mode and Black Probe on Source, Red on Drain
Reading: OL

2.a - DMM in diode mode and Black Probe on Drain, Red on Gate
Reading: 0.8V but slowly decreasing
2.b - DMM in diode mode and Black Probe on Gate, Red on Drain
Reading: OL
 
Last edited:

BobTPH

Joined Jun 5, 2013
8,688
1. is testing the reverse body diode of the MOSFET and gives the expected result.

2. does not test anything useful.

I assume the source is connected to ground. Test the voltage with black on source and red on drain. Get readings both when it should be on and when it should be off.
 

MrAl

Joined Jun 17, 2014
11,281
|[ With regard to removing bad winding turns from the motor itself ]|
Thank God, I don't have to do such thing! That wouldn't probably (be) worth the value of a new motor! lol. At least in my case, no?
It's not really that hard to do. If it is just a few turns it works pretty good.
In my case, I am not even sure if I could get a new motor it depends if the manu sells parts for the microwave or just repairs them.
Or alternately, tells you to go out and buy a new microwave :)
 

Thread Starter

PsySc0rpi0n

Joined Mar 4, 2014
1,744
1. is testing the reverse body diode of the MOSFET and gives the expected result.

2. does not test anything useful.

I assume the source is connected to ground. Test the voltage with black on source and red on drain. Get readings both when it should be on and when it should be off.
Not sure I understood what you told me in 1. You are telling me what the test is "testing", right? And then saying that the results I got are the expected ones? Is that it?

It's not really that hard to do. If it is just a few turns it works pretty good.
In my case, I am not even sure if I could get a new motor it depends if the manu sells parts for the microwave or just repairs them.
Or alternately, tells you to go out and buy a new microwave :)
I don't doubt of your skills. I doubt of my own skills. lol
And in my case, I think there are motors for sell with the same reference, so probably would be better to purchase a new one other than to be disassembling the motor case, remove turns of te winding and putting it all back together, risking to damage the motor and have to buy a new one anyways! :p

--------------

Now, I decided to put my DMM in diode mode again and test the diodes that I can see / identify and all but one read around 0.595V (black on K, red on A) and OL (black on A, red on K). This other one is measuring around 0.146V (black on K, red on A) and around 1.8V (black on A, red on K).
I removed the diode from the circuit (dessoldered it) and repeated the test. Same readings.
Is this diode damaged given the readings?
 

MrAl

Joined Jun 17, 2014
11,281
[Removing turns of wire from a motor]
I don't doubt of your skills. I doubt of my own skills. lol
And in my case, I think there are motors for sell with the same reference, so probably would be better to purchase a new one other than to be disassembling the motor case, remove turns of te winding and putting it all back together, risking to damage the motor and have to buy a new one anyways! :p
Oh ok :)
You might surprise yourself though.
Unfortunately, I do not remember all the details of what it was like to take the motor itself apart, but it could not have been too hard to do.
One small motor I worked on had metal tabs that were bent over and that held the case together. By gently bending the tabs I could get the motor case apart to get at the windings. Bending them back when reassembling did not break them so it was good to go. Since the metal was some sort of soft steel, I would think a little solder would have worked also when reassembling if the tabs broke off.
 

BobTPH

Joined Jun 5, 2013
8,688
Not sure I understood what you told me in 1. You are telling me what the test is "testing", right? And then saying that the results I got are the expected ones? Is that it?
Yes. In an N channel MOSFET there is a diode with cathode at the drain and anode at the source. When you tested from drain to source what diode range, that is exactly what you saw.

Testing between the gate and the source or drain should show no connection. If they do connect, the insulation is blown.

Neither of these tests says anything about whether the MOSFET is good, though either of them might show that it is bad.
 

Thread Starter

PsySc0rpi0n

Joined Mar 4, 2014
1,744
Yes. In an N channel MOSFET there is a diode with cathode at the drain and anode at the source. When you tested from drain to source what diode range, that is exactly what you saw.

Testing between the gate and the source or drain should show no connection. If they do connect, the insulation is blown.

Neither of these tests says anything about whether the MOSFET is good, though either of them might show that it is bad.
I think today I'm not at my best reading answers and understanding them.
So, just to make sure we're on the same page.
Test 1 is ok to be done and the readings are telling that the MOSFET is likely ok, right?
Test 2 says nothing about the condition of the MOSFET.

What about the diodes? What can you tell me about my readings?
 

Thread Starter

PsySc0rpi0n

Joined Mar 4, 2014
1,744
You have to test that a voltage on the gate turns it on and off appropriately.I suggested a way in post #10.
So, from what I understand, I should inject voltage directly to the MOSFET and see if it turns on? Is that it? Or you guys mean to connect the board to the charger and check it that way?
Please, bare with me, I have no experience in fixing electronics!
 
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