Roberts Revival R550 poor volume level. - UK Vintage Radio Repair and Restoration Discussion Forum

GarGriff · 5th May 2019, 10:52 am

I bought this lovely radio off a stall at Retford's Friday flea market on a whim on the basis that if it didn't work I could have my money back. It does work, I've bought a new telescopic aerial, a PP9 and a mains adaptor for it. I've also sent a not inconsiderable time cleaning and polishing it.

The issue I have is that it only produces a very low volume which is great when I'm sitting in my office early in the morning when everything is quiet but the rest of the time it is too quiet to hear above the background noise.

Is there a simple fix? One that doesn't require oscilloscopes, soldering irons and a degree in electronics, none of which I have?

I don't want to take it to a repair shop to be laughed at and be charged £50 for a repair to a radio that only cost me £15 in the first place.

paulsherwin · 5th May 2019, 11:38 am

This is a 1996 model. You could try cleaning the headphone socket with a bit of white spirit or WD40 - proper contact cleaner would be better, but I assume you don't have any. Apart from that, there's not much you can do given your level of expertise.

Station X · 5th May 2019, 11:38 am

If you don't want to do any testing or soldering your actions are rather limited.

Does the set have a headphone socket? If so its contacts may be dirty. Try inserting and removing a plug from the socket several times, which may clear it.

Station X · 5th May 2019, 11:39 am

We both seem to be singing from the same hymn sheet!

Mike. Watterson · 5th May 2019, 2:41 pm

These may have been cheap Chinese chassis branded Roberts by Glen Dimplex. I seem to remember some of these being very expensive (nearly £100) but same insides as a £12 no-name model, unlike the "World Radios" which were rebranded Sangen. I may though be thinking of much later AM/FM modern "Roberts" in vaguely 1970s style.

Not sure when they bought the "label". If so they may use a headphone amplifier in bridge mode for the small loudspeaker, so may not be very loud.
How does it sound with regular earbud or similar headphones?

ronbryan · 5th May 2019, 2:57 pm

The R550 circuit is the same as the R250, where the audio amplifier is a TDA7231 chip. There is a 470uF capacitor coupling the amplifier pin 2 to the speaker via the aforesaid headphone jack switch.

Ron

paulsherwin · 5th May 2019, 3:00 pm

Mike, the Revivals were (and still are) very expensive for what they were, but sold quite well because of the retro styling and Roberts name. Roberts customers have always been middle class people who aren't price conscious.

GlenDimplex bought Roberts in 1994.

Assuming Ron is right, the speaker coupling cap could well be faulty. The OP isn't going to be able to check it without help though.

Mike. Watterson · 5th May 2019, 11:46 pm

They'll capacitor may have partially dried out. Someone with test gear and soldering iron needed, esp if it's low on the headphone socket too.
At least unlike newer portable radios it does have a "real" audio amp for a loudspeaker.

GarGriff · 26th May 2019, 10:32 am

I've tried cleaning the earphone socket with WD40 and also ispropanol but no joy.

AC/HL · 26th May 2019, 12:08 pm

You could try making a post here: https://www.vintage-radio.net/forum/...play.php?f=145, just a chance that it's something simple, bearing in mind it's value.

5th May 2019, 10:52 am	#1
GarGriff Retired Dormant Member Join Date: May 2019 Location: Sheffield, South Yorkshire, UK. Posts: 2	Roberts Revival R550 poor volume level. I bought this lovely radio off a stall at Retford's Friday flea market on a whim on the basis that if it didn't work I could have my money back. It does work, I've bought a new telescopic aerial, a PP9 and a mains adaptor for it. I've also sent a not inconsiderable time cleaning and polishing it. The issue I have is that it only produces a very low volume which is great when I'm sitting in my office early in the morning when everything is quiet but the rest of the time it is too quiet to hear above the background noise. Is there a simple fix? One that doesn't require oscilloscopes, soldering irons and a degree in electronics, none of which I have? I don't want to take it to a repair shop to be laughed at and be charged £50 for a repair to a radio that only cost me £15 in the first place.

5th May 2019, 11:38 am	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,965	Re: Roberts Revival R550 poor volume level. This is a 1996 model. You could try cleaning the headphone socket with a bit of white spirit or WD40 - proper contact cleaner would be better, but I assume you don't have any. Apart from that, there's not much you can do given your level of expertise.

5th May 2019, 11:38 am	#3
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Roberts Revival R550 poor volume level. If you don't want to do any testing or soldering your actions are rather limited. Does the set have a headphone socket? If so its contacts may be dirty. Try inserting and removing a plug from the socket several times, which may clear it. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

5th May 2019, 11:39 am	#4
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Roberts Revival R550 poor volume level. We both seem to be singing from the same hymn sheet! __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

5th May 2019, 2:41 pm	#5
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Roberts Revival R550 poor volume level. These may have been cheap Chinese chassis branded Roberts by Glen Dimplex. I seem to remember some of these being very expensive (nearly £100) but same insides as a £12 no-name model, unlike the "World Radios" which were rebranded Sangen. I may though be thinking of much later AM/FM modern "Roberts" in vaguely 1970s style. Not sure when they bought the "label". If so they may use a headphone amplifier in bridge mode for the small loudspeaker, so may not be very loud. How does it sound with regular earbud or similar headphones?

5th May 2019, 2:57 pm	#6
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,960	Re: Roberts Revival R550 poor volume level. The R550 circuit is the same as the R250, where the audio amplifier is a TDA7231 chip. There is a 470uF capacitor coupling the amplifier pin 2 to the speaker via the aforesaid headphone jack switch. Ron

5th May 2019, 3:00 pm	#7
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,965	Re: Roberts Revival R550 poor volume level. Mike, the Revivals were (and still are) very expensive for what they were, but sold quite well because of the retro styling and Roberts name. Roberts customers have always been middle class people who aren't price conscious. GlenDimplex bought Roberts in 1994. Assuming Ron is right, the speaker coupling cap could well be faulty. The OP isn't going to be able to check it without help though.

5th May 2019, 11:46 pm	#8
Mike. Watterson Heptode Join Date: Dec 2014 Location: Limerick, Ireland. Posts: 901	Re: Roberts Revival R550 poor volume level. They'll capacitor may have partially dried out. Someone with test gear and soldering iron needed, esp if it's low on the headphone socket too. At least unlike newer portable radios it does have a "real" audio amp for a loudspeaker.

26th May 2019, 10:32 am	#9
GarGriff Retired Dormant Member Join Date: May 2019 Location: Sheffield, South Yorkshire, UK. Posts: 2	Re: Roberts Revival R550 poor volume level. I've tried cleaning the earphone socket with WD40 and also ispropanol but no joy.

26th May 2019, 12:08 pm	#10
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Roberts Revival R550 poor volume level. You could try making a post here: https://www.vintage-radio.net/forum/...play.php?f=145, just a chance that it's something simple, bearing in mind it's value.