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Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE! |
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22nd Apr 2016, 11:27 am | #1 |
Pentode
Join Date: Jul 2007
Location: Salisbury, Wiltshire, UK.
Posts: 174
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Fidelity UA3 Record player/Radio
A Fidelity UA3 I was Given. The Turntable was completely seized. The potentiometers were so corroded on the centres of the wiper contacts, that contact cleaner would have been effective. So I stripped all the potentiometers and wave change switches apart, cleaned and re tensioned all the contacts. All the controls now work with no hint of crackling whatsoever. The performance on the Radio is very good, certainly a very usable item and pleased with the overall result, roughly 3 hrs work.
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22nd Apr 2016, 12:56 pm | #2 |
Heptode
Join Date: Sep 2013
Location: Manchester, UK.
Posts: 860
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Re: Fidelity UA3 Record player/Radio
I used to have one of these. FM was very good. Quality was suprisingly good for what it was, as you can see there's not much to it inside. Last time I saw one of these may have been when I had one which I sold in about 1986.
Regards, Paul
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...No, it's not supposed to pick up the World Service, it's not a radio! |
22nd Apr 2016, 1:09 pm | #3 |
Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 17,820
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Re: Fidelity UA3 Record player/Radio
Looks a lot like their contemporary RAD- series radios with a mains supply and beefier power output stage added
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22nd Apr 2016, 4:47 pm | #4 |
Pentode
Join Date: Jul 2007
Location: Salisbury, Wiltshire, UK.
Posts: 174
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Re: Fidelity UA3 Record player/Radio
The text in the original thread should have bees: contact cleaner would have been uneffective
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24th Apr 2016, 9:57 am | #5 |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,482
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Re: Fidelity UA3 Record player/Radio
These were right in the middle of the 4-5 year period that I spent as a 'brown goods' technician.
The UA3 is memorable for having been the source of the worst 'occupational' electric shock I ever received, one I still remember vividly to this day - I was holding the PCB standing up on edge with one hand and somehow managed to put my other hand on the small section of the PCB which had mains on it. I was quite shaken for several hours afterwards. Luckily I was also quite young and fit - about 20. The main failures on these were the finned audio power amplifier ICs (SN76013?). We kept a floating stock of about half a dozen just for these units. |
24th Apr 2016, 10:20 am | #6 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,822
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Re: Fidelity UA3 Record player/Radio
I had one of these a while back having bought it "for old times sake" as I repaired a number of them in my late teens and as Sirius says mostly the TEXAS SN76013 amplifier chips at fault.
The performance was quite reasonable for the price the big downside was the speakers which I found truly dreadful. They had bits of foam to try stop bits of the cabinet vibrating but it doesn't work. Mine now sold on is here http://www.radiomuseum.org/r/fidelit...aster_ua3.html Cheers Mike T
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Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
24th Apr 2016, 11:39 am | #7 | |
Dekatron
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 17,820
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Re: Fidelity UA3 Record player/Radio
Quote:
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24th Apr 2016, 7:44 pm | #8 |
Administrator
Join Date: Dec 2002
Location: Cardiff
Posts: 9,059
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Re: Fidelity UA3 Record player/Radio
I had one of those as a child. As others have said the speakers are awful, being plastic boxes with bits of wood stuck on two sides. I'm sure many people connected better speakers, which would be lower impedance (the originals are 16 ohm) and more likely to damage the amplifier ICs. Mine needed one (or maybe both) of these replacing which was done by a local shop, even though I was using the original speakers.
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24th Apr 2016, 8:45 pm | #9 |
Octode
Join Date: Aug 2005
Location: Saltburn-East, Cleveland, UK.
Posts: 1,784
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Re: Fidelity UA3 Record player/Radio
I owned a UA4, which was just a record player (i.e. no radio section) that also used the ill fated SN76013ND ic's. Mine eventually lost the audio output with a loud crackle prior to failing. Unfortunately I had neither the experience nor funds at around the age of 14 years old to repair it.
I believe that the early demise of the ic's was due to them being run quite close to their maximum operating voltage. The speakers supplied with most Fidelity units of this type weren't particularly good, but most Fidelity gear was built to a budget price. Andrew |
1st May 2016, 9:14 pm | #10 |
Heptode
Join Date: Feb 2014
Location: Nottingham, UK.
Posts: 645
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Re: Fidelity UA3 Record player/Radio
This brings back a few memories... The SN76013 output IC we nicknamed the 'Spiny Norman' by us apprentices because of it's cooling fins and the Monty Python hedgehog of the time!
If I recall, the output stage would go into oscillation as the supply rail decayed at switch-off. There might be a modification you could apply to the Ic to prevent this happening. Some said at the time that this caused the IC to fail, rather than actual breakdown of the IC in the first place. Fidelity were renowned for fitting the bare minimum of components. Nice to hear that this one has survived. SJM. |