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Old 6th Aug 2022, 2:50 pm   #1
IanNVJ35
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Default Almost unused Roberts RCS80 portable

At a house clearance I picked up a Roberts RCS80 that looks almost factory fresh. Sadly the disuse meant that the ancient metal Ever Ready batteries had gone to town in the battery tray. Well I got that all sorted by taking out all metal parts and deep cleaning and washing the plastic. The radio fired up straight away and sound quality is excellent. Really well balanced.

But the set does have a small issue. That of two of the LCD segments being triggered erroneously. The bottom part of one digit and the kHz symbol when listening to FM.

Usually this is caused by some contamination on the LCD drive pins. But before I start pulling it all apart does anyone know how easy it is to access the LCD? I don't want to mess up a working radio for a trifle but on the other hand the set is so clean I'd ideally like to get it 100%.

I really like 80's design. Crisp and functional so I'm pleased to get one.

Thanks for any help. Ian
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Old 9th Aug 2022, 11:39 pm   #2
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Default Re: Almost unused Roberts RCS80 portable

Well Iam giving it a go. It was very fiddly to get apart but made it in the end. I get the feeling that this mysterious fluff is slightly conductive. I'm going to clean it all up anyway. No obvious spills or dried fluid splash.
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Old 10th Aug 2022, 9:20 am   #3
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Default Re: Almost unused Roberts RCS80 portable

Some of those strands look like Tin Whiskers. Is the "Fluff" all over the set or just on the row of connection at the side of the LCD?

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Old 10th Aug 2022, 9:56 am   #4
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Default Re: Almost unused Roberts RCS80 portable

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Originally Posted by 60 oldjohn View Post
Some of those strands look like Tin Whiskers. Is the "Fluff" all over the set or just on the row of connection at the side of the LCD?

John.
Whatever it is, it had made its way through the button holes in the top of the set and landed on the PCB and contacts below.

I will fire it up later, see if we have cleared the issue. I feel that it is 'bedroom fluff' from the look of it but of course can't be sure. The actual radio had no real visible dust at all on it. At the same time I may address the slightly unresponsive preset No.3 button.
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Old 10th Aug 2022, 10:42 pm   #5
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Default Re: Almost unused Roberts RCS80 portable

I'm pleased to say it's now fixed. Not the unusual dust but a tiny spot of battery acid dried residue shorting out some pins under the pcb. It looked like flux residue but it wasn't. So all fixed and I'm pleased.
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Old 10th Aug 2022, 11:09 pm   #6
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Default Re: Almost unused Roberts RCS80 portable

Good news Ian. Corroded batteries can cause all sorts of grief.
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Old 27th Sep 2022, 10:23 pm   #7
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Default Re: Almost unused Roberts RCS80 portable

Quick update after a month or so of use. It does chew through batteries somewhat, and I tested the drain on the batteries when off - its 0.5 mA. I know it powers the clock and memory etc, so is never truly 'off' but does this sound typical?

Also. if anyone knows if the schematic is available a pointer where would be really appreciated.
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Old 28th Sep 2022, 1:02 am   #8
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Default Re: Almost unused Roberts RCS80 portable

The full manual is in the files at the Roberts group -

https://groups.io/g/robertsradiogroup

which should be easy to join and comes without obligations. It's in the form of eight .jpg files, we made .pdfs of many Hacker and Roberts manuals years ago but clearly I missed doing this one.

Paul
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Old 28th Sep 2022, 9:56 am   #9
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Default Re: Almost unused Roberts RCS80 portable

It depends on what type of batteries it uses. But 0.5mA idle current when switched off for this type of radio sounds quite reasonable. I would make sure you use good quality high powered batteries if you cannot run it off the mains.
Good news that you found the fault and a very worthwhile repair.
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Old 28th Sep 2022, 11:17 am   #10
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Default Re: Almost unused Roberts RCS80 portable

It will obviously help battery life if you can keep it hooked up to the mains when not in use.
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Old 3rd Oct 2022, 10:17 pm   #11
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Default Re: Almost unused Roberts RCS80 portable

Thanks for the input - always appreciated. Good to know that is a reasonable current, I may just use mains as suggested.

I will download a circuit diagram though (thanks for the link) to look at what is running at all times and if I find a fault I will of course update. May be another spot of battery gunge somewhere!
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Old 6th Oct 2022, 10:32 am   #12
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Default Re: Almost unused Roberts RCS80 portable

I too have just repaired one of these radio's,and impressive they are indeed.
Mine had suffered several faulty "tact" keyboard switches,but replacements are still available!
I checked the consumption of my set in "stand-by",ie just clock functioning,and it's 4.5mA.
With set functioning fully,the consumption is 100mA,increasing of course with volume setting.
Very nicely made electronics,obviously of far eastern origin.
A great performer,with typical nice Roberts sound quality.
I am particularly impressed with the a.m. performance,the mw sensitivity is very good.
Nick
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Old 6th Oct 2022, 10:16 pm   #13
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Default Re: Almost unused Roberts RCS80 portable

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Originally Posted by Max Ripple View Post
I too have just repaired one of these radio's,and impressive they are indeed.
Mine had suffered several faulty "tact" keyboard switches,but replacements are still available!
I checked the consumption of my set in "stand-by",ie just clock functioning,and it's 4.5mA.
With set functioning fully,the consumption is 100mA,increasing of course with volume setting.
Very nicely made electronics,obviously of far eastern origin.
A great performer,with typical nice Roberts sound quality.
I am particularly impressed with the a.m. performance,the mw sensitivity is very good.
Nick
Thanks Nick. In fact you pre-empted my next question...please can someone with the same set measure standby current! May I ask, was that on mains? Just that going via the transformer will skew the readings. If you could supply 9 V dc to the battery terminals and measure with a multimeter that would be so appreciated.

Just I have it open and nothing visible is amiss. Don’t want to start fault finding if there is no fault!
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Old 7th Oct 2022, 10:36 am   #14
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Default Re: Almost unused Roberts RCS80 portable

Yes,that test was with batteries.
There is some impressive circuitry in there.The clock and memories are backed up,but there is no sign of a back up battery.
I was puzzled by the fact that when you switch off,without batteries inserted,or mains connected,the clock still run's!
It must a capacitive back up system,as I spotted a large electrolytic cap in there an addition to the power supply resevoir.There may be some back up integral to the Toshiba upc too?Your service info should prove to be a good read?
Again,good design overall?
Nick
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Old 7th Oct 2022, 10:05 pm   #15
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Default Re: Almost unused Roberts RCS80 portable

Quote:
Originally Posted by Max Ripple View Post
Yes,that test was with batteries.
There is some impressive circuitry in there.The clock and memories are backed up,but there is no sign of a back up battery.
I was puzzled by the fact that when you switch off,without batteries inserted,or mains connected,the clock still run's!
It must a capacitive back up system,as I spotted a large electrolytic cap in there an addition to the power supply resevoir.There may be some back up integral to the Toshiba upc too?Your service info should prove to be a good read?
Again,good design overall?
Nick

Thank you Nick for confirming. I've just reassembled the set. And I absolutely agree, it's got some excellent internals. The speaker is above what I expected to see, made in Thailand but with a hefty shielded magnet. The clock keeps excellent time, noting the hefty internal capacitors. All in all I'm delighted.

I first saw this set in Roberts own book about the company. It was a new release, but I never saw one in the flesh until I found this one.

Thanks again and hope you enjoy using your set too.
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Old 7th Oct 2022, 11:30 pm   #16
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Default Re: Almost unused Roberts RCS80 portable

Just sharing a picture. Nice design
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Old 10th Oct 2022, 5:40 pm   #17
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Default Re: Almost unused Roberts RCS80 portable

Great looking radio.

l've got a Hacker Herald in the garage which is a similar design, and it's a lovely set. No AC though.
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Old 14th Oct 2022, 9:34 pm   #18
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Default Re: Almost unused Roberts RCS80 portable

Out of interest I tried it on mains. It really did transform the sound, much more powerful. The service manual states 4 Watts of audio vs 1.5 Watts when using batteries. So if you own one of these sets, do try mains if you can.
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