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Old 2nd Sep 2017, 11:51 pm   #1
LiamGP42
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Default Roberts RCS80. Scratchy dials & leaky caps.

Hello,

I recently picked up a Roberts RCS80, it's working fine other than scratchy volume, bass and treble dials.

I took the radio apart with the intention of cleaning the scratchy dials, when I took it apart I noticed around three or four capacitors had leaked, they weren't bulging at the top but brown stains were around the bottom of them on the pcb.

I had a look at the instant download/ DVD that is available to purchase but it doesn't seem to have the schematics for the Roberts RCS80. if it's just not listed I'm happy to buy it but if it's not there does anyone have a scan of the manual?

Also had a quick look at some of the other RCS80 threads and I'm wondering even though some caps have leaked should I leave them alone as the radio is working fine or should I go ahead an replace them.

Below is whats written on the side of each capacitor that seems to have leaked.
- Giant 470 uF 25v
- Giant 2200 uF 25v
- Telecon 1000 uF 16v
- 4700 uF 6.3v

So I suppose my question is, should I leave it alone as it's working or should I replace the ones that have leaked. If you think I should replace them can I just order the above from ebay??

Thanks
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Old 3rd Sep 2017, 12:47 am   #2
AC/HL
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Default Re: Roberts RCS80. Scratchy dials & leaky caps.

That appears to be the remnants of adhesive rather than leakage.
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Old 3rd Sep 2017, 9:52 am   #3
canonman75
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Default Re: Roberts RCS80. Scratchy dials & leaky caps.

That looks like glue to me as well. It's what they use to hold the more bulky components in place before wave soldering the PCB.
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Old 3rd Sep 2017, 11:54 am   #4
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Default Re: Roberts RCS80. Scratchy dials & leaky caps.

Yep, it's most probably glue (somewhat similar to Evostik Contact adhesive) commonly used in Japanese equipment and now in Chinese equipment (although they tend to use glue gun adhesive)
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Old 3rd Sep 2017, 12:18 pm   #5
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Default Re: Roberts RCS80. Scratchy dials & leaky caps.

If it's "that glue", it needs to be removed. It starts off a yellowish colour and turns brown over time. As it does so, it becomes conductive. This youtube video has more information:
https://youtu.be/yy8NS2zejhQ
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Old 3rd Sep 2017, 2:08 pm   #6
LiamGP42
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Default Re: Roberts RCS80. Scratchy dials & leaky caps.

Hi all,

Thanks for the advice and info, I've had another look and I'm pretty sure the few bits of glue aren't conductive. So I cleaned the scratchy dials, put it back together and its good as new.

Fingers crossed it goes for another thirty or so years.

Thanks again

One thing I did note is that when I press one of the scan buttons, as the radio is scanning for the next station I can very faintly hear the station that I was listening to before hitting the scan button. Is this normal or a cause for concern?
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