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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

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Old 4th Apr 2019, 2:49 pm   #1
Join Date: Mar 2019
Location: Bournemouth, Dorset, UK.
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Default Roberts 505

my first post, a question please I have just recently bought a Roberts 505, which I am cleaning and tidying up externally, I can only receive VHF, and there is a humming sound, which is tolerable, but can anything be done inside the radio to make the humming sound go?
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Old 4th Apr 2019, 3:05 pm   #2
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Default Re: Roberts 505

Do you mean an R505?

This is a battery transistor radio so it's not clear why it would be humming.
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Old 4th Apr 2019, 3:48 pm   #3
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Default Re: Roberts 505

There is a DC input skt on the radio, are you using an adapter to power the radio. If so try batteries as Paul suggests.
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Old 6th Apr 2019, 2:03 pm   #4
David G4EBT
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Default Re: Roberts 505

It's a good idea to check the current being drawn because it's not uncommon in my experience for C40 - a 680F cap, to go short circuit. When testing a 505, it's as well to insert a meter on say the 10Amp range or whatever, in series with the battery, switch on briefly and if the consumption is more than a few mA, and the output pair of transistors get hot very quickly, it's more likely C40 that's the culprit. If C41 and/or C42 are leaky they can increase battery drain and lower the voltage so are also worth checking.

Even if all seems well or the set has other faults, given the hassle they can cause, it's as well to change those caps after almost six decades since they left the factory.

See this thread:

Also, Post #8 here:

Hope that might help a bit.
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Old 25th May 2019, 10:17 am   #5
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Location: Glossop, Derbyshire, UK.
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Default Re: Roberts 505

I have just bought a R505 for the vast cost of 8 and as David said C40 was indeed S/C ( quick easy repair thanks ) now I have cleaned it up it looks and sounds great only fault is the caps on the volume/tone knobs . Has anyone got a clue where I can get new ones?

Thanks Dave L
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