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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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20th Sep 2022, 7:53 pm | #1 |
Heptode
Join Date: Jul 2020
Location: Larkhall, South Lanarkshire, Scotland.
Posts: 671
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My Latest Junker. Courier AM Car Radio.
Picked up cheap on ebay as a wee project, Courier AM Car radio, Tunes and seem's to receive well enough but the volume is quiet, Suspect electrolytic caps, Audio amp seem's to produce a loud buzz / crackle so confident it's working, According to radio museum it dates from 68, But uses modern silicon transistors and an IC Audio amp, The radio museum one is badged up as a radiomobile. I'd date it to the late 70s early 80s.
https://www.radiomuseum.org/r/radiomobil_75.html
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20th Sep 2022, 8:32 pm | #2 |
Heptode
Join Date: Mar 2017
Location: Romsey, Hampshire, UK.
Posts: 523
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Re: My Latest Junker
Hi
That audio amplifier IC looks suspiciously like the Plessey SL402/403 or badge-engineered Sinclair IC-10. I like the ingeneous braided thermal bridge from heatsink to case. I remember those ICs from the late 1960's. They had enormous gain, and it was very hard to make them stable and avoid earth loop effects from circulating currents. A few minutes self oscillation at supersonic frequencies would send them into thermal destruction. The loss of hard earned pocket money somehow sticks in the memory...... More here: https://sound-au.com/articles/pwr-amp-dev.htm#s5a |
20th Sep 2022, 8:40 pm | #3 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,006
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Re: My Latest Junker
I see Lockfit transistors. Known to suffer failures.
Also the blue-sleeved electrolytics can be problematic [I've had to replace a few in Pye Westminster two-way radios]. Car radios get to see a lot wider temperature-and-humidity ranges than domestic electronics, so parts that might last for 60 years in a domestic setting can be brought to failure in half that time when in a car.
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20th Sep 2022, 8:48 pm | #4 |
Heptode
Join Date: Jul 2020
Location: Larkhall, South Lanarkshire, Scotland.
Posts: 671
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Re: My Latest Junker
Thanks for the info, Well judging by the replies it could well date to the late 60's, Wasn't aware silicon transistors and IC's Were that common back then.
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20th Sep 2022, 8:54 pm | #5 |
Octode
Join Date: Sep 2020
Location: Thetford, Norfolk, UK.
Posts: 1,741
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Re: My Latest Junker
Interesting little set. Very compact.
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20th Sep 2022, 8:56 pm | #6 |
Heptode
Join Date: Jul 2020
Location: Larkhall, South Lanarkshire, Scotland.
Posts: 671
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Re: My Latest Junker
For the time period it is yeah,
Might use the pre-set button for a bluetooth conversion
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20th Sep 2022, 9:50 pm | #7 |
Heptode
Join Date: Apr 2003
Location: Ayr, Ayrshire, UK.
Posts: 631
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Re: My Latest Junker
This set is mid 70's : my brother had one and managed to blow up the audio IC which if I remember correctly was one of the TBA641 types. I was able to fix it with the correct IC but the radio is long gone now.
Andy
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G-QRP #12697 Last edited by radioman; 20th Sep 2022 at 9:52 pm. Reason: typo |
20th Sep 2022, 10:06 pm | #8 |
Heptode
Join Date: Jul 2020
Location: Larkhall, South Lanarkshire, Scotland.
Posts: 671
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Re: My Latest Junker
Cheers, That date seem's about right to me,
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21st Sep 2022, 11:17 am | #9 |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,988
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Re: My Latest Junker
The centre of the PCB looks scorched, what has caused that?
John.
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21st Sep 2022, 11:22 am | #10 |
Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 17,858
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Re: My Latest Junker
I can't see that (could be my eyes though!). Whereabouts exactly?
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21st Sep 2022, 11:27 am | #11 | |
Heptode
Join Date: Jul 2020
Location: Larkhall, South Lanarkshire, Scotland.
Posts: 671
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Re: My Latest Junker
Quote:
One of the cap's is dated 73 so that ties in with radioman's date
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21st Sep 2022, 1:29 pm | #12 |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,988
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Re: My Latest Junker
Unconventional way of marking photo, but the mark I saw is under the paper clip. On the reverse side that area is distorted by the light. I hope you find it is just a faulty capacitor.
John.
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21st Sep 2022, 3:19 pm | #13 | |
Heptode
Join Date: Jul 2020
Location: Larkhall, South Lanarkshire, Scotland.
Posts: 671
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Re: My Latest Junker
Quote:
Still has a very low volume issue, Loud - ish buzz from the speaker when i touch the volume contacts, Any idea's ?
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21st Sep 2022, 5:01 pm | #14 |
Heptode
Join Date: Jul 2020
Location: Larkhall, South Lanarkshire, Scotland.
Posts: 671
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Re: My Latest Junker
Radio Fixed and sound's great, Was fixed ''by accident'' Anybody want to have a guess at what the problem was ?
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21st Sep 2022, 5:19 pm | #15 |
Octode
Join Date: Sep 2020
Location: Thetford, Norfolk, UK.
Posts: 1,741
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Re: My Latest Junker
The gold coloured 1000uF?
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21st Sep 2022, 5:21 pm | #16 |
Heptode
Join Date: Jul 2020
Location: Larkhall, South Lanarkshire, Scotland.
Posts: 671
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Re: My Latest Junker
No cigar for you
HINT it wasn't a capacitor
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21st Sep 2022, 6:31 pm | #17 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
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Re: My Latest Junker
Carbonised circuit board?
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21st Sep 2022, 6:34 pm | #18 |
Heptode
Join Date: Jul 2020
Location: Larkhall, South Lanarkshire, Scotland.
Posts: 671
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Re: My Latest Junker
Look's like nobody want's my cigar's
Keep the guesses coming will reveal the answer at 10 pm
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21st Sep 2022, 6:59 pm | #19 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,935
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Re: My Latest Junker
Last thought, braid earthing screw not tightened up enough?
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21st Sep 2022, 7:01 pm | #20 |
Heptode
Join Date: Jul 2020
Location: Larkhall, South Lanarkshire, Scotland.
Posts: 671
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Re: My Latest Junker
Afraid not
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