Author Topic: Replacing a 150nf x2 and resistor id  (Read 1941 times)

Gattopardo

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Replacing a 150nf x2 and resistor id
« on: 31 March, 2018, 02:23:41 am »
So am replacing an 150nf x2 capacitor, it seems that i can get a 100nf or 220nf quickly but not a 150nf.   :facepalm:  Ordering a couple or 5 150nf capaciators failed to make them deliver as they were out of stock.

Would fitting either the 100 or 220 make a difference?



Looking at the resistor the colours are brown black green and gold with to 10 x100 (1000 or 1k) with a 5% yet using an online calculator i get 1m resistance


Re: Replacing a 150nf x2 and resistor id
« Reply #1 on: 31 March, 2018, 09:16:20 am »
I think more detail is needed. What is the application? Can you use say a 100 nF and a 47 nF in parallel? Have you got the right voltage rating?

The rectangular box isn't like any resistor that I've seen. A better photo would help. It could be a contact supressor that contains a resistor and a capacitor in series.
Quote from: Kim
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Gattopardo

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Re: Replacing a 150nf x2 and resistor id
« Reply #2 on: 01 April, 2018, 05:48:02 am »
250v across the terminals in a numatic vacuum, one without a cord rewind.


Re: Replacing a 150nf x2 and resistor id
« Reply #3 on: 01 April, 2018, 06:43:47 am »
A resistor with brown, black and green bands is 1 MOhm. Brown is 1, black is 0 and green is 5, meaning five zeros, so the value is 1000000 Ohms. Gold is the tolerance (5%)

That is used to discharge the capacitor so you can't get a shock from the pins of the plug.

If the capacitor is across the supply terminals, it is to suppress noise and possibly reduce arcing in the switch as it turns on and off. The value is arbitrary and either 100 or 220 nF would be fine.
Quote from: Kim
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Gattopardo

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Re: Replacing a 150nf x2 and resistor id
« Reply #4 on: 02 April, 2018, 03:35:41 pm »
The resistor melted the metal leg between the capaciator.

Kim

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Re: Replacing a 150nf x2 and resistor id
« Reply #5 on: 02 April, 2018, 04:47:27 pm »
A 1M resistor across the mains shouldn't be getting hot enough to melt anything.  It'll dissipate a little under 60mW.  I suspect the capacitor has failed.

Re: Replacing a 150nf x2 and resistor id
« Reply #6 on: 03 April, 2018, 10:11:08 pm »
Be very careful...
You need class X or Y rated capacitors for mains use.
https://www.allaboutcircuits.com/technical-articles/safety-capacitor-class-x-and-class-y-capacitors/
The  resistor is fitted to discharge the capacitor if the appliance is turned off and then unplugged. It must have the correct Voltage rating (power is not everything!).


Gattopardo

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Re: Replacing a 150nf x2 and resistor id
« Reply #7 on: 04 April, 2018, 12:56:43 am »
A 1M resistor across the mains shouldn't be getting hot enough to melt anything.  It'll dissipate a little under 60mW.  I suspect the capacitor has failed.
Not looked at it but suspect something is a foot.

Gattopardo

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Re: Replacing a 150nf x2 and resistor id
« Reply #8 on: 09 April, 2018, 10:33:41 am »
So bought the correct bits from cricklewood electronics...lets see what happens now...