[SOLVED] Old capacitor needs replacing not sure what to replace with.

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crysotyle

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I renovate cine projectors, and I have come across the below capacitor which has three leads and not sure what to replace it with, anybody got any ideas.

Hunts
Capacitors
0.1+0-005+0.005
25v A.C Wkg
to B.S.S.613
List No. Z497 A
11W

Three wires two reds and green

 

Hi,

The wiring and the values are shown on the capacitor.
You may try to find a similar one or use three capacitors.
EMI suppression capacitors
* type X between L and N
* type Y between L and Earth, N and Earth.

Klaus
 
The casing has a schematic of 3 capacitors with internal connections:
0.1 uF
.005uF
.005uF

25 VAC Wkg means it was made to endure 25VAC working voltage. It's paper type. Non-polarized.

11W suggests it was made to carry 11 Watts. This suggests it heats up. (I could be wrong.)
 

The chances of finding an exact replacement are virtually zero but as Klaus suggested, you can replace it with three single capacitors. Wire it exactly as on the body diagram:
0.1uF (=100nF) across the two brown wires
0.05uF (=50nF) from each brown wire to the green wire.

They should be rated for 250V AC ! (or higher - 275V AC is the modern standard)
The BSS613 is a reference to British Standard Specification 613 which relates to interference supression devices.

I would guess 11W is a date code, I doubt it refers to a power rating.
Note that although 50nF is available, the more common equivalent standard value these days is 47nF, it will work equally well.

Brian.
 

I am with Brian, that MOST LIKELY the rating is not 25VAC, but 250 VAC.

What happened to the wire insulation? And the loose wire strands in the bottom left corner?
That looks like an accident waiting to happen.
 

I've seen this before, it probably dates back to the 1950's or very early 60's before PVC was used for insulation. The wires are covered in some kind of rubber insulation that dries out and fractures (nearly used the banned c**** word then!) especially in hot environments. The rheostat would probably make the whole thing quite hot and prone to failure. After fracturing, chunks of the insulation crumble and just fall off.

Sadly, the same insulation was used in house wiring, safe if left alone but it disintegrates wen touched.

Brian.
 


The small capacitor is 0.005 uF = 5 nF, so 4.7 nF should be a good replacement.

It must be of type "Y" for safety reasons.
 

Must be my eyesight failing... yes, it is 5nF although 50nf would probably work better.
There is a small 'Y' near the value and a small 'X' near the 100nF.

Brian.
 

Got all new silicon covered wire, safe up to 200 degrees in all the colours needed, for any wire that needs replacing.
 

So I have taken another image just to confirm I would need 3 capacitors to replace this one not sure there would be enough space in the base for three. Will look at some sizes of them.
 

For safety reason the class X and Y must be respected. Since the class Y capacitors are connected between line and earth they cannot be too high in value in order not to generate high leakage current. A capacitor of 5 nF has an Xc of about 650 K at 50 Hz, that means an rms current of 240/650k = 375 uA.
 
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    FvM

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    crysotyle

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Look here at the 'Wima' branded capacitors.
https://www.rapidonline.com/Catalogue/Search?Query=capacitors&Attributes={"Voltage":["250V"]}
They are actually quite small. If the appearance of the unit isn't important after repair, you could consider using an IEC mains filter. You can get them with in/out tags or with a built in mains socket to take a standard 3-pin IEC plug. If you use a chassis mounted IEC filter, make sure it is securely bolted down to the projector chassis because it forms the Earth connection through it's mounting holes.

Brian.
 

So I think I have found the ones, two of the first 50nf going from each brown wire to the green and one 100nf across the two brown wires. I assume that the Y2 and X2 sub standards don't make much difference to my install as X2 is ≤2.5kV and Y2 is 150VAC≤ V<300VAC Rated Voltage.Both appear to be above what I need.
 

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    Nickkcin

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They should be fine. They exceed the rating of the originals and are also probably more reliable and effective than the original type too.

Brian.
 

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    Nickkcin

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As explained in post #11, the capacitance of the Y capcitor shouldn't be larger than 5 nF to avoid too high ground leakage current.
 

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    Nickkcin

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Hi All so below is my solution to replacing the capacitors, might not be how others would do it but it is based on the information I got will try it late once I have tested it with Pat Tester I have.

 

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    Nickkcin

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