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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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21st Jun 2018, 7:41 am | #21 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,328
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Re: Marconiphone 4633 (actually a 4366) Speaker problem
Can we be clear in that when you tsted the RH speaker with a 1.5V battey as suggested, you got no cone movement/scratching sound? If that's correct, double check the speaker's voicecoil for continuity.
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Edward. |
21st Jun 2018, 7:48 am | #22 |
Retired Dormant Member
Join Date: Dec 2007
Location: Shropshire, UK.
Posts: 3,051
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Re: Marconiphone 4633 (actually a 4366) Speaker problem
Looks as though there's a problem with the RH. amplifier, which might well have killed the speaker. Don't sub the other speaker at this stage in that case!
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21st Jun 2018, 2:56 pm | #23 |
Rest in Peace
Join Date: Mar 2011
Location: Basildon, Essex, UK.
Posts: 4,100
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Re: Marconiphone 4633 (actually a 4366) Speaker problem
It looks like this chassis has Callins capacitors on it, if they are going short circuit then who knows what may have happened.
Mike |
21st Jun 2018, 4:12 pm | #24 |
Retired Dormant Member
Join Date: Jun 2018
Location: Cambridgeshire, UK.
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Re: Marconiphone 4633 (actually a 4366) Speaker problem
That doesn't sound good!
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21st Jun 2018, 4:24 pm | #25 |
Retired Dormant Member
Join Date: Jun 2018
Location: Cambridgeshire, UK.
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Re: Marconiphone 4633 (actually a 4366) Speaker problem
Just to be sure I got no sound whatsoever with the speaker no movement no scratching noises. I even tried it with a 9v battery.
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21st Jun 2018, 8:32 pm | #26 |
Heptode
Join Date: Dec 2016
Location: Sheffield, South Yorkshire, UK.
Posts: 539
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Re: Marconiphone 4633 (actually a 4366) Speaker problem
Yes it does use Callins or Lorlin electrolytic capacitors.
The speakers are 15 ohms. If one of them is faulty it might have taken out the push pull output stage VT20 and VT18. Transistors OP9A - which are R2322 or BRC6109 OP9B - which are R2322 or BRC5296 |
22nd Jun 2018, 6:14 am | #27 | |
Rest in Peace
Join Date: Mar 2011
Location: Basildon, Essex, UK.
Posts: 4,100
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Re: Marconiphone 4633 (actually a 4366) Speaker problem
Quote:
Mike |
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22nd Jun 2018, 2:52 pm | #28 |
Heptode
Join Date: Dec 2016
Location: Sheffield, South Yorkshire, UK.
Posts: 539
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Re: Marconiphone 4633 (actually a 4366) Speaker problem
A child poking something in the grid slots of the cabinet could damage the speaker. Things like grids and vents fascinate young children.
I remember running a pencil up and down the back of TV back cover because it made a very musical sound. Didn't do any damage to it though. And my nephew poked my tweeters out with his fingers! I told his dad. "yes he did the same to mine" was his reply! |
22nd Jun 2018, 3:56 pm | #29 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,328
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Re: Marconiphone 4633 (actually a 4366) Speaker problem
Based on the OP's latest Post, it does look like the speaker has (most unusually) failed.
It is not quite so easy to go and buy a 15 ohm 8" x 5" unit these days. Before the search for one starts, that amplifier channel needs a good going over. If it's an economic repair, then think about another speaker. The OP might seek hands-on help, if needed, via this Forum.
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Edward. |
24th Jun 2018, 1:09 am | #30 |
Heptode
Join Date: Dec 2016
Location: Sheffield, South Yorkshire, UK.
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Re: Marconiphone 4633 (actually a 4366) Speaker problem
I think it would cheaper and simpler to replace both speakers with other 15 ohm types. They don't have to be the same shape as the originals. It's not as though they are on display. He will just have to either remove the mounts for the old speakers. Then use screws or clamps to mount the new ones.
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