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| Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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1st Feb 2021, 2:12 pm
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#21 |
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Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
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Re: Stereosound radiogram
Circuit diagram with 56K grid leak resistor added.
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1st Feb 2021, 8:06 pm
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#22 |
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Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
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Re: Stereosound radiogram
As it is on all wavebands, I would vote for the tuning condensor. There should be a wire clip on the shaft that maintains the earth connection during rotation and may not be making good contact.
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1st Feb 2021, 8:13 pm
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#23 | |
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Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,433
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Re: Stereosound radiogram
Quote:
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Frank |
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1st Feb 2021, 9:10 pm
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#24 |
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Nonode
Join Date: Nov 2016
Location: Aberaeron, Ceredigion, Wales, UK.
Posts: 2,887
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Re: Stereosound radiogram
I was thinking the same as PJL, as it on all wave bands. Also worth checking the valve base, fractured socket?
John |
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1st Feb 2021, 9:16 pm
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#25 |
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Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
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Re: Stereosound radiogram
The tuning capacitor is ok, good continuity between chassis and the tuning capacitor.
The only way of checking the valve base is by replacing it, wriggling the valve makes no difference. |
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1st Feb 2021, 10:24 pm
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#26 |
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Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,422
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Re: Stereosound radiogram
Hi.
The drawing is slightly wrong, both control grids are strapped. Its just incorrectly drawn. Although I'm not familiar with the particular set one question, does this set use a PCB or is it hand wired? The reason I ask is that recently I had another set with the same issue that used a PCB. The board wasn't brilliant and neither was the valve base. After cleaning the PCB with a fibreglass pen and IPA, plus a new base the set worked perfectly.
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Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member Last edited by murphyv310; 1st Feb 2021 at 10:39 pm. |
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1st Feb 2021, 11:35 pm
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#27 |
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Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
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Re: Stereosound radiogram
I vowed never to touch another PCB valve radio after the last where I had to lift critical valve base grid pins and wire point to point...a PCB valve TV was a crazy idea right from the start.
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1st Feb 2021, 11:40 pm
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#28 |
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Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,422
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Re: Stereosound radiogram
Agreed.
The heat from the valves can cause carbonised boards, they are paper based of course, then they also can suffer in the damp so it's a kind of a no win situation. The bases in some sets left a lot to be desired as well.
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Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member |
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1st Feb 2021, 11:54 pm
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#29 |
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Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,433
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Re: Stereosound radiogram
Well they were designed to a price and to last 10 possibly at a push 15 years, if they met the service life with few repairs then the design was ok.
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Frank |
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2nd Feb 2021, 1:23 am
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#30 |
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Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
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Re: Stereosound radiogram
It doesn't have a PCB, its all point to point chassis wiring. What is odd is that the record deck is a BSR UA25 and it looks original.
Yes there are a few errors to the circuit. I've solved it. The grid leak resistor was reading high, more to the point when I put a meter across it, its resistance crept up to around 60K. I thought it was a 56K but was in fact 47K, a new resistor restored normality. Photo's tomorrow. |
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2nd Feb 2021, 6:00 pm
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#31 |
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Nonode
Join Date: Nov 2016
Location: Aberaeron, Ceredigion, Wales, UK.
Posts: 2,887
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Re: Stereosound radiogram
Glad you sorted out the problem.
John |
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