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| Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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24th Sep 2017, 10:50 am
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#1 |
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Triode
Join Date: Sep 2012
Location: Sulaimanyha, Iraq.
Posts: 30
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Saba wildbad11...need help
Hi every one
i have a SABA wildbad 11 with a problem of low sound volume specially on the AM and SW. the FM is a bit better the tubes and the caps. are replaced with new ones. i checked the audio output transformer and the primary coils measures 525 ohms and the secondary coils the one connected to the speakers measures 0.5 ohm  while the other secondary coil measures 45 ohmsdoes that mean that there is a short circuit on that part of the transformer the speakers measures 5 ohms each can anyone help me so solve that problem? one other question is that ..what is the Si.6 stand for which is seen in the schematic on the primary side of the audio output transformer much obliged Aras |
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24th Sep 2017, 11:37 am
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#2 |
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Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,433
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Re: Saba wildbad11...need help
I think the transformer is ok, one low impeadance winding for the speakers and a higher impeadance for the feedback winding.
The Si6 appears to be a 70ma time delay fuse, see list on circuit diagram for fuse types. Perhaps Si6 is only fitted to certain models.
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Frank |
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24th Sep 2017, 11:45 am
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#3 |
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Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Saba wildbad11...need help
0.5 ohm for the loudspeaker secondary winding is ok, Si6 indicates a fuse which might or might not be present in your radio.
EDIT: Post crossed. Lawrence. |
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24th Sep 2017, 12:35 pm
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#4 |
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Triode
Join Date: Sep 2012
Location: Sulaimanyha, Iraq.
Posts: 30
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Re: Saba wildbad11...need help
thank you very much Frank
i did some signal tracing and the audio output of pin 7 of EL84 is good but it weakens on the the secondary of the output transformer...is that normal?? thanks a lot Aras |
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24th Sep 2017, 3:49 pm
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#5 |
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Triode
Join Date: Sep 2012
Location: Sulaimanyha, Iraq.
Posts: 30
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Re: Saba wildbad11...need help
Thank you very much for your help.
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24th Sep 2017, 5:57 pm
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#6 |
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Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,433
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Re: Saba wildbad11...need help
What are you using to signal trace, if you are measuring the AC signal voltage on the primary and secondary the secondary will be smaller but the current will be larger due to the impedance difference.
The transformer could be faulty but I am not yet convinced.
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Frank |
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24th Sep 2017, 8:29 pm
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#7 |
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Triode
Join Date: Sep 2012
Location: Sulaimanyha, Iraq.
Posts: 30
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Re: Saba wildbad11...need help
i'm using an AF&RF signal tracer
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24th Sep 2017, 8:56 pm
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#8 |
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Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,433
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Re: Saba wildbad11...need help
Have you a signal generator to feed a signal into the volume control, that way you can determine if you have an audio fault or a RF/IF fault. You could try an MP3 player to feed a signal in. If you have no SG, the matching will be wrong but it may confirm or not the audio stage.
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Frank |
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24th Sep 2017, 9:44 pm
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#9 |
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Triode
Join Date: Sep 2012
Location: Sulaimanyha, Iraq.
Posts: 30
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Re: Saba wildbad11...need help
I'll try that.
Thanks a lot. |
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