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Old 23rd May 2020, 7:28 pm   #21
A_W_TYE
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Default Re: Which cap?

Quote:
Originally Posted by David G4EBT View Post

As to your Stella ST239U, perhaps the most critical capacitor - the audio coupling capacitor (.022uF).

Cap changed.
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Old Yesterday, 5:16 pm   #22
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Default Re: Stella 239U. Capacitor ID.

Hi all,


Confused again cap 57 in the list say's 0.1, I take it that is uf.
the cap is in the audio circuit the physical mesurement is
32cm long and 17cm diameter and capacitance is 462pf
so going by that I cannot see how it is 0.1uf.
I think it says 0.5uf.


Thank you.
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Last edited by A_W_TYE; Yesterday at 5:23 pm. Reason: Addition to post
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Old Yesterday, 5:37 pm   #23
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Default Re: Stella 239U. Capacitor ID.

C57 is the anode decoupler for V5a and is wired between ground and the junction of R36/R24. 0.1uF would be a sensible value, but there may have been changes during production.

Are you sure you have the correct capacitor? Check the colour code of the two resistors it's connected to.
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Old Yesterday, 6:32 pm   #24
A_W_TYE
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Default Re: Stella 239U. Capacitor ID.

Hi Graham,


The colour code of the resistors it is connected to are
correct it is the right one.
This cap is the only one left on the underside
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Last edited by A_W_TYE; Yesterday at 6:46 pm. Reason: Addition to post
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Old Today, 7:59 am   #25
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Default Re: Stella 239U. Capacitor ID.

I'd go ahead and replace it with the value shown in the service sheet then.
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Old Today, 4:44 pm   #26
dazzlevision
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Default Re: Stella 239U. Capacitor ID.

I attach some scans from the official Stella 239U service manual: circuit (in 2 parts) and the under chassis layout.

From the parts list, I see that there is (rather surprisingly) an 820pF 400V 10% PAPER capacitor used: C47, Philips part number 48.75.10/820E.
So, we now know where the capacitorís 820E marking comes from. C47 forms part of the de-emphasis filter on VHF/FM.

In the Stella manual, C57 is a 0.1uF 400V 10% paper type, part number 48.751.10/100K.
It is connected at the junction of two resistors: R36 (100kOhm) and R24 (220KOhm), in the triode anode circuit of the UABC80 valve V5.

Looking at the parts list, it looks like these paper capacitors capacitance value marking system is as follows:
8E2 = 8.2pF (where E = pF and is the decimal pointís position)
820E = 820pF
1K = 0.001uF (where K = 1nF)
1K5 = 0.0015uF (1.5nF and is the decimal pointís position)
10K = 0.01uF (10nF)
22K = 0.022uF (22nF)
47K = 0.047uF (47nF)
100K = 0.1uF (100nF).

C51 (1000pF, 1300Vdc, 20%, paper) is mounted on top of the audio output transformer.
Attached Files
File Type: pdf Stella 239U circuit part 1.pdf (1.04 MB, 4 views)
File Type: pdf Stella 239U circuit part 2.pdf (1.01 MB, 4 views)
File Type: pdf Stella 239U underchassis layout.pdf (972.9 KB, 2 views)
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Old Today, 8:34 pm   #27
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Default Re: Stella 239U. Capacitor ID.

Well you live and learn! It had to be Philips/Stella to different!
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