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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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16th Apr 2021, 10:58 pm | #1 |
Hexode
Join Date: Nov 2009
Location: Cambridge, Cambridgeshire, UK.
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Yamaha Amplifier has magnets glued to sides of relay....
Not something I have seen before, but there are two magnets glued either side of the relay by the contacts.
It appears that they may have been fitted as an aftermarket modification. But what are they there for? Arc damping? The relays are switching audio to speakers. |
16th Apr 2021, 11:08 pm | #2 |
Moderator
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Location: Oxford, UK
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Re: Yamaha Amplifier has magnets glued to sides of relay....
Is this the speaker protection relay? Somebody may have fitted the magnets as a bodge to improve relay operation (though you can buy a new relay for a couple of quid).
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16th Apr 2021, 11:14 pm | #3 |
Hexode
Join Date: Nov 2009
Location: Cambridge, Cambridgeshire, UK.
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Re: Yamaha Amplifier has magnets glued to sides of relay....
Should have mentioned that....
Yes speaker protection and switching relays. There are three relays ( three sets of speakers) , one relay I would say is an original matsushita, the two with magnets are DEC. The magnets are no where near the coils but right next to the contacts. |
16th Apr 2021, 11:19 pm | #4 |
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Re: Yamaha Amplifier has magnets glued to sides of relay....
You do sometimes get contact problems with protection relays after a couple of decades.
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16th Apr 2021, 11:26 pm | #5 |
Hexode
Join Date: Nov 2009
Location: Cambridge, Cambridgeshire, UK.
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Re: Yamaha Amplifier has magnets glued to sides of relay....
Yup, contacts do wear and get tarnished... but why the magnets?
Do they magnetise the contacts so they attract each other? If I get relay contacts that have a problem , I just clean them with acetone and duraglit. |
17th Apr 2021, 12:12 am | #6 |
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Re: Yamaha Amplifier has magnets glued to sides of relay....
All I can think of is that they are intended to make the relays pull down harder. I'm only guessing though, and it might just be some sort of audiophool nonsense.
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17th Apr 2021, 12:55 am | #7 |
Moderator
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Re: Yamaha Amplifier has magnets glued to sides of relay....
Rather like archaeologists putting all unknown artefacts down to something used in a religious ceremony, we could see every bit of weirdness added to an audio item as phoolery there may be some justification.
I wonder if there is some other justification. Are the coil ratings written on the case? and do they suit the power supply? It could be as innocent as someone trying to make do with whatever relays they had to hand when some originals failed. Bodge or foo? not much of a choice. I think I'd find out what the originals were and replace them. Either way, I'd be embarrassed if anyone saw something like that in an amp I'd been associated with. David
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17th Apr 2021, 1:14 am | #8 | |
Heptode
Join Date: Oct 2009
Location: Melbourne Australia
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Re: Yamaha Amplifier has magnets glued to sides of relay....
Quote:
Magnets are sometimes used for polarity sensitive protection contacts to force a longer arc length during the opening of a contact. That said, the magnets would have to be oriented in such a way that the magnetic field was cutting across the direction of an arc, so hopefully the bodge had that aspect correct. Maybe a keen amateur had just read some commercial blurb on protection cbs/contactors, or just cracked open such a protective device and recovered the magnets from there. |
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17th Apr 2021, 2:11 am | #9 |
Octode
Join Date: Jul 2011
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Re: Yamaha Amplifier has magnets glued to sides of relay....
That echoes my thoughts exactly.
Steve.
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17th Apr 2021, 7:34 am | #10 |
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Re: Yamaha Amplifier has magnets glued to sides of relay....
Is there some boutique firm out there selling 'Magic Magnets' at silly prices with a little pamphlet telling you where to play around with sticking them? Maybe this amp was someone doing their research before putting them on the market? We'll never know unless someone pops their head above the undergrowth.
David
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17th Apr 2021, 7:57 am | #11 |
Nonode
Join Date: Jun 2016
Location: Bognor Regis, West Sussex, UK.
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Re: Yamaha Amplifier has magnets glued to sides of relay....
The same magnet fitments were discussed on audiokarma in 2018, the OP was about a Nikko Alpha 440 but by about the 5th post someone was reporting that these fitted OEM by Yamaha.
https://audiokarma.org/forums/index....-relay.814043/ The thread includes pictures. |
17th Apr 2021, 9:17 am | #12 |
Octode
Join Date: Feb 2006
Location: Bristol, UK.
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Re: Yamaha Amplifier has magnets glued to sides of relay....
It looks as though magnets on relays are meant for high current applications:
https://www.durakoolrelays.com/infor...-why-use-them/ I'd be surprised if they have any effect at audio power levels |
17th Apr 2021, 9:35 am | #13 |
Hexode
Join Date: Jan 2013
Location: Kelvedon, Essex, UK.
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Re: Yamaha Amplifier has magnets glued to sides of relay....
what is the model number of the amp
John. |
17th Apr 2021, 10:04 am | #14 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
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Re: Yamaha Amplifier has magnets glued to sides of relay....
Could the amp have a fault, e.g. slight/intermittent/unstable DC offset that causes the protection circuit to operate and open the contacts, or stop them closing in the first place, or maybe the amp is OK and the protection circuit is faulty, and the magnets are a bodge to keep the contacts closed? They may have shifted them about until they closed the contacts successfully.
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17th Apr 2021, 10:42 am | #15 |
Octode
Join Date: Jan 2003
Location: Ware, Herts. UK.
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Re: Yamaha Amplifier has magnets glued to sides of relay....
Magnets are often used on heavy current contactors to "blow-out" any arc that may develop when the contactor is breaking a large current. The magnets serve to direct the arc plasma away from the contacts thus reducing contact erosion due to the very high local temperatures encountered.
John |
17th Apr 2021, 10:53 am | #16 |
Hexode
Join Date: Jun 2018
Location: Buckinghamshire, UK.
Posts: 381
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Re: Yamaha Amplifier has magnets glued to sides of relay....
Most so called 'speaker protection' relays don't stand much chance against an output device going dead short. They often aren't rated sufficiently to break the DC current and may just arc until the contacts burn away or the PSU blows a fuse (or the speaker goes open circuit...).
Shorting out the speakers using changeover contacts will give them a fighting chance even if the relay doesn't survive, and at least the arcing into the short will likely blow the fuse quicker. Blowout magnets may help to reduce the arcing problem, but are usually fitted inside the relay. If Yamaha have indeed glued them to the outside of a normal relay, this is likely an attempt at a lower cost solution then a much larger and correctly rated relay. A photo from the previously mentioned AudioKarma thread alledgedly showing a number of relays from Yamaha with magnets attached:- It's seems pretty unlikely it could have had any value as a marketing gimmick, and since it still adds a cost to them over the basic relay one might imagine/hope they did the appropriate testing to prove any benefit Cheers |
17th Apr 2021, 3:40 pm | #17 |
Hexode
Join Date: Nov 2009
Location: Cambridge, Cambridgeshire, UK.
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Re: Yamaha Amplifier has magnets glued to sides of relay....
I have delved a little deeper...
The amp is a MX-1000 Yamaha rated around 250W per channel. The relays ARE original. Removing the duct tape over the magnets there is a black fibre tape underneath. Which is probably original. So as has been mentioned, the magnets were very likely fitted by Yamaha! |
17th Apr 2021, 5:31 pm | #18 |
Moderator
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Re: Yamaha Amplifier has magnets glued to sides of relay....
The Japanese marketing departments are always on the lookout for some new selling point. I bought a new CD player a few years ago. Sony made a big thing about R-core mains transformers and there being TWO of them as well as the chassis being copper plated.
Did they really believe this made any difference? I wonder if Yamaha's little magnets made it into their brochure? If no-one knows about the foo, how can it work? David
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17th Apr 2021, 9:14 pm | #19 | |
Hexode
Join Date: Jun 2018
Location: Buckinghamshire, UK.
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Re: Yamaha Amplifier has magnets glued to sides of relay....
Quote:
Cheers |
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17th Apr 2021, 9:26 pm | #20 | |
Hexode
Join Date: Nov 2009
Location: Cambridge, Cambridgeshire, UK.
Posts: 489
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Re: Yamaha Amplifier has magnets glued to sides of relay....
Quote:
The relays exactly match the ones in the MX-1000. Mark |
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