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Old 20th Sep 2021, 4:30 pm   #1
DMcMahon
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Default Unusual Capacitor Marking

While doing some cleaning on my Uher 4400 Report Stereo IC Reel to Reel tape recorder, I noticed a small capacitor (C74) that initially looked like it had a solder splash at one end. On closer inspection see that it is somewhat unusual in having metal contact bands at each end, the right hand one having some solder present on it.

On the schematic it is shown as 1,000pF (i.e. 1 nF) but the marking on it appears to show 1nS possibly followed by 0 or O, or maybe it is 0SUL when rotated 180.

This is on the right channel of the amplifier board, on the left channel C73 looks the same.

Any ideas ?

David
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Old 20th Sep 2021, 4:59 pm   #2
ms660
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Default Re: Unusual Capacitor Marking

Tubular ceramic, they also come encapsulated.

Lawrence.
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Old 20th Sep 2021, 7:58 pm   #3
John_BS
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Default Re: Unusual Capacitor Marking

I think the letter "S" might indicated the tolerance (-20 /+50%)
John
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Old 20th Sep 2021, 8:03 pm   #4
Jon_G4MDC
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Default Re: Unusual Capacitor Marking

Looks like same construction as dog bone ceramic without a complete covering.
Maybe it's done with something transparent instead? Must be sealed against moisture somehow.
(Or looking again maybe it isn't. )
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Old 21st Sep 2021, 4:00 am   #5
joebog1
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Default Re: Unusual Capacitor Marking

I think its the "earthy" end of the cap. Its solder looking because it is very metallic and the outside conductor of the cap. The inside of the ceramic tube will most likely be "painted", with the same material all the way through.

Unless Im very much mistaken !!
YES I am very much mistaken.

But I agree tubular ceramic and VERY reliable.

Joe
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Old 22nd Sep 2021, 10:56 am   #6
DMcMahon
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Default Re: Unusual Capacitor Marking

These are connected between base and emitter of the first transistor in the Playback/Record amplifiers so do not connect to earth directly.

The end in question is set back from the right hand side of the body by a couple of mm while the left hand metallic contact ring is right at the end of the capacitor body.

Thank you to everybody for your inputs, I had heard of dog bone capacitors and resistors before but never really knew what they looked like.

I assume the yellow dab on left hand side is the temperature coefficient.

David
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Old 22nd Sep 2021, 12:26 pm   #7
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Default Re: Unusual Capacitor Marking

It is 1n SC tubular ceramic

S is tolerance and C is temperature co-efficient - I can't remember off the top of my head what they are in numerical values.
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Old 22nd Sep 2021, 12:38 pm   #8
DMcMahon
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Default Re: Unusual Capacitor Marking

Yes the O could well be a C.

I assume the 1n must be 1nF, otherwise a coincidence because its value is 1nF (1,000pF).

David
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Old 22nd Sep 2021, 12:43 pm   #9
DMcMahon
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Default Re: Unusual Capacitor Marking

Quote:
Originally Posted by Terry_VK5TM View Post
It is 1n SC tubular ceramic

S is tolerance - I can't remember off the top of my head what they are in numerical values.
From Johns Post #3 -20%/+50%

David
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