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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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23rd May 2020, 7:28 pm | #21 | |
Pentode
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Re: Which cap?
Quote:
Cap changed.
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Alan. |
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25th May 2020, 5:16 pm | #22 |
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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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Alan. Last edited by A_W_TYE; 25th May 2020 at 5:23 pm. Reason: Addition to post |
25th May 2020, 5:37 pm | #23 |
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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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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
25th May 2020, 6:32 pm | #24 |
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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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Alan. Last edited by A_W_TYE; 25th May 2020 at 6:46 pm. Reason: Addition to post |
26th May 2020, 7:59 am | #25 |
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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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Graham. Forum Moderator Reach for your meter before you reach for your soldering iron. |
26th May 2020, 4:44 pm | #26 |
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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 capacitor’s 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 point’s position) 820E = 820pF 1K = 0.001uF (where K = 1nF) 1K5 = 0.0015uF (1.5nF and is the decimal point’s 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. |
26th May 2020, 8:34 pm | #27 |
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Re: Stella 239U. Capacitor ID.
Well you live and learn! It had to be Philips/Stella to different!
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28th May 2020, 10:41 am | #28 |
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Re: Stella 239U. Capacitor ID.
Hi All,
As Graham has sugested I am replacing cap 57 with a 0.1uf, and not what was fitted. I dont why a cap of that size was fitted originally.
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Alan. |
28th May 2020, 10:43 am | #29 | |
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Re: Stella 239U. Capacitor ID.
Quote:
Thank you, have saved for future Ref.
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