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Old 22nd Apr 2016, 11:27 am   #1
plaka78
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Default 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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Old 22nd Apr 2016, 12:56 pm   #2
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Default 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.

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Paul
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Old 22nd Apr 2016, 1:09 pm   #3
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Default 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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Old 22nd Apr 2016, 4:47 pm   #4
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Default 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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Old 24th Apr 2016, 9:57 am   #5
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Default 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.
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Old 24th Apr 2016, 10:20 am   #6
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Default 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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Old 24th Apr 2016, 11:39 am   #7
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Default Re: Fidelity UA3 Record player/Radio

Quote:
Originally Posted by Cobaltblue View Post
I love the way that the model ID label is slapped-on upside down and at a 45 degree angle. Doesn't exactly inspire confidence in the assemblers' pride in their workmanship.
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Old 24th Apr 2016, 7:44 pm   #8
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Default 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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Old 24th Apr 2016, 8:45 pm   #9
AndiiT
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Default 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
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Old 1st May 2016, 9:14 pm   #10
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Default 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.
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