vintage capacitor type: "SBL"

Thread Starter

bobbyrae

Joined May 14, 2009
42
I am looking at the schematic for my 1970's receiver and there is one type of capacitor it lists that I just can't figure out: SBL. I have searched many electronics places on the internet and there doesn't seem to be any mention of anything like that.

Maybe SBL is some brand? See attached photo. An example value is .0018(J) and I am pretty sure that (J) is a tolerance, I think 5%.

I guess I could open it up and take a photo of the actual capacitors if necessary.

Here's a possible hint. A different model receiver schematic from the same maker shows capacitors the same way, but has a table that calls them "BL ceramic"

Thanks
 

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retched

Joined Dec 5, 2009
5,197
Hmm. Boundary Layer is the only thing I can think of.

Maybe small boundary layer. Just guesses.

I would guess a high quality, non polarized cap would do the trick.

A photo would be most helpful.

[ed]

Ok, here you are, it is a Styrene-Butadiene Latex capacitor.
[/ed]
 
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CWB

Joined Jun 25, 2010
1
i found the styrene reference as well .
as was mentioned , a picture (and a link to a schematic if possible) would help out .
i did find a reference to what could be a "potted" array/filter assembly ...
i recall that a few receivers from that era did use these in the FM section .
 

Thread Starter

bobbyrae

Joined May 14, 2009
42
Attached is a section of the schematic. I am glad that you guys asked my for this because in doing so I had to enlarge the schematic on my system and found that all the solid dots I HAD seen ended up being concentric circles! Which means mylar film instead of the weird SBL.

It's still hard to see, but I am glad I have such a high res version of the schematic. The section seems to be the tone control because it sits between the two main amp sections.

And I am shrinking things a bit for upload, so it doesn't show all that well...

But now I see two caps that have "B.P" next to them and wonder what THAT means!
 

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Thread Starter

bobbyrae

Joined May 14, 2009
42
After combing the schematic at hi-res, I actually found one of those SBL types. The attached snapshot shows C408 with value 0.0068. The photo shows the actual cap on the board, the green thing in the middle. It doesn't look like there is much writing on it, and I don't think I could make it out without pulling it.

And by the way, it DOES appear to be the FM section!
 

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bertus

Joined Apr 5, 2008
19,942
Hello,

Do you mean the green capacitor next to the coil?
That looks like a ceramic capacitor.

Bertus
 

Thread Starter

bobbyrae

Joined May 14, 2009
42
I pushed some stuff out of the way. It says

Rich (BB code):
  V 
682 K
Does the appearance guarantee that it is just a ceramic? I found another on the board that looks about the same, only slightly larger in size, but the schematic does not put a black dot next to this other one. Of course, sometimes things are not exactly as indicated on the schematic, are they?
 

retched

Joined Dec 5, 2009
5,197
6,800pF / .0068uF Ceramic 682
that 682 is a Ceramic.

If the capacitance, voltage and the polarity is the same, you CAN interchange caps. (You can also go with higher voltages)

Different blends will have different leakages and such, and some are "cleaner" sounding for use in filters.

Some materials make better capacitors than others, but it is typically what you want to spend.

A cheap audio product can be made to sound better by simply upgrading the caps to same value caps of better audio performing materials.
 
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