What component is this? varistor? capacitor? something else?

Thread Starter


Joined Jan 13, 2017
Hi Everyone
Thank you for this great Forum
It helped me a few time and i decided to register here to post a question that i cant find anywhere.

I have 2 Segway X2 with the same problem (not Charging batteries)
I Found that the power supply had a blown fuse (4Amp 250V PCB mounted) and also this component that i can't find anywhere using the letters and numbers printed on it.
Looks like a ceramic disk capacitor, but no farad value in it.
might be a varistor... but can't find any reference of this component anywhere online

may a request a bit of help from you guys?

Thank you very much in advance


Thread Starter


Joined Jan 13, 2017
Wow, thank you very much Jony130
really appreciate the quick reply.

Might be able to get my segways charging now.

Thank you

Thread Starter


Joined Jan 13, 2017
Hey Thank you very much for your replies

I have attached a photo of the circuit board
This one is missing the fuse because i was testing it with a 4A car fuse (and it works), so i have ordered a bag of 10 of these fuses (as they keep blowing)

I have a few segways and this is a common issue when you charge them with a 230v petrol generator.... its not the first time I have to replace the Fuses
I could swap them with 5A or 6A... but i prefer to replace fuses instead of other components.

The first time i had to fix these Power supplies i was a bit scared with them...
The output of them is around 300V DC
This was the first time i had one of this capacitors blowing up ( they open up like a pretty black flower hahah)

Thank you for you help guys
Let me know if you need (or want) more photos



Joined Nov 30, 2010
That, "NTC" with a blow-out is not a capacitor. It's a varistor which has some specified resistance when cold and less resistance when hot.
Either that or somebody created, "The NTC Corporation" and they make capacitors.:rolleyes:
NTC means, "negative temperature coefficient". Is that the part you wish to replace?
Last edited:
Hi, the light brown component looks like high voltage cap and the position where it is soldered is signed with C5
therefor I think Jony130 is right. But if this cap is blown your generator is not good for charging electronic
The board looks like it is just a rectifier and some filtering. Try to run the board with some medium resistive load
(a high power resistor or a light bulb) and you should be able to find where the circuit is interrupted.

Thread Starter


Joined Jan 13, 2017
Hi Guys
Thank you once again
Also appreciate the Links you posted

Regarding the Circuit board:
the black NTC will be replaced as its clearly dead
Waiting for the PCB mounted 4A fuses to arrive
The yellow(light brown) 10nF capacitor will be replaced (on a different board)
Can i replace this yellow capacitor with ANY 10nF cap? or doues it have to be "that one"?

I really don't know if you are interested in the back story of this circuit(and the other 8 dead ones that I have here), but I will make it fast.
The company i work for owns around 80 of these segways

This circuit board is the "Charging port" power supply inside the segways (an absolute pain to get to on the newer model)
Several times a week we have groups of segways going out in the fields around the country and the only option to charge them is to use generators
We use Honda EU30i inverter (these are the one most stable and reliable generators we can find at the moment)

The problem here is (I think), these segways are being connected to the charging points with the generator OFF or...
To many segways are being connected to mains at the same time which in my point of view creates voltage drops and power surge in the generator.
This is what i thing its killing these power supplies and obviously, segway does not sell this circuit board alone (in fact they charge £400 +VAT for the "charging Kit"... and we know that we can fix it with less than £10)

As you can tell already, I am not an expert with electronics... I am just very curious and I have learned a lot of the basics online and by taking things apart (and blowing some others haha)

Sorry for the long post
Thank you for you patience and time guys
Hi Garras, you can replace the C5 with a High Voltage Cermaic Disc Capacitor of the same parameters.
This are 10 nF and 1 kV. Possible are also Foil capacitors for Filters but check the rated voltage
( per example from WIMA or RIFA)
Hi Garras, you can replace the C5 with a High Voltage Cermaic Disc Capacitor of the same parameters.
This are 10 nF and 1 kV. Possible are also Foil capacitors for Filters but check the rated voltage
( per example from WIMA or RIFA)
Replace Y capacitors with Y or XY capacitors when they connect to the AC line. Please. They are also typically self-healing and don't like to start fires.

Over the years, I have increased the reliability of a lot of laboratory stuff. Three items stand out:

1. A Thermocouple scanner operating near a temperature controlled water cooled 1000 W IR lamp.
The scanner had places for a regulator etc, but just adding a few transorbs solved the issue in all of the scanners we owned. I could have added all of the parts.

2. A Multichannel Analyzer kept blowing one particular board that cost $1000 USD to repair/exchange. I told the company that there was no protection at all in the power supply. They politely told me that they require the device to operate on 120 V 60 Hz. Spikes are out of that range. An external surge suppressor did the trick.
I do pick ones with connected equipment warranties. i.e. ISOBAR On a monitor, we did exercise the connected device warranty for the ISOBAR. Just keep your receipts.

3. Two systems that ran every day were partly composed of computers with 8" floppy drives that I self-maintained in a self-repair, repair/exchange contract. The computers were becoming obsolete and were having more failures. Using both an ISOBAR surge suppressor and a OneAC/PowerOne power conditioner the only problems were dust and floppy drives. A more modern Macintosh system replaced this and ran for 17 years with only dust and floppy issues. The HD was still working after 17 years of use. This protection ran about $1000 USD. It protected a lot more equipment than the computer. Repair prices were about 1/2 the value of the equipment. Lost time, much more than the cost of the protection.