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Old 12th Feb 2019, 11:45 am   #1
microkid
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Smile Tannoy Jupiter J40 Tweeter Repairs

I have just starte dto restore a pair of Tannoy Jupiter J40 speakers. These were part of the Tannoy Planet series of speakers introduced around 1984 and also included the Mercury M20, Venus V30, Saturn and M20. The Jupiter was the top of the range model and also the largest.

I have a couple of issues to resolve on these units the first is a non functioning open circuit tweeter. I believe the tweeter used is a Seas H253 (Ferro Fluid) item, however I have no actual evidence to support this just a bit of internet research. What I would say though is that the tweeters I have do not look exactly like the items in the Seas H253 data sheet.

A quick test with a multimeter has confirmed that one unit is open circuit (the other unit measures about 5.4 Ohms).

These appear to be fairly standard looking 1” soft dome tweeters – undo 4 faceplate screws, remove face plate and separate voice coil and diaphragm from the magnet assembly.

On the rear of the diaphragm assembly is a rubber gasket, when this is removed you can see the two very fine copper wires running between the voice coil and the terminals. On inspection I can see one is broken where it runs on to the coil. So using a pair of tweezers I gentle pull it back unwinding it between a fifth and a quarter of a turn. The wire now exits the voice coil at about 3.30 position (as per clock face ) where as original it was about 5.30 position.

Using a similar piece of fine tin copper wire I have extended the broken piece such that I can now run it back to the terminal and solder the other end in place.

Refitting the rubber gasket not only completely hides this repair but also clamps the wire nicely in place against the back of the flat plastic plate. Checking with meter I am now reading 5.4 Ohms – which is a result.

After full reassembly I test it again with the multi meter and get 5.4 Ohms reading again, and can also hear a faint crackle as the meter energises the tweeter.

I have not yet tested the unit in the speaker as I have them fully stripped down and I also plan to open up both tweeters again to replace the ferrofluid before final reassembly.

Has anybody else performed a similar repair and did they notice any effect from reducing the voice coil by a small amount (in this case less than 20mm). I can’t imagine it will make any audible difference – and certainly less than replacing with a ‘equivalent’ tweeter. I would be interested in hearing thoughts / experiences on this.

Next stage is to look at one of the woofers that is scraping a bit, I hadn’t noticed this before so will try a few tricks to realign it, before doing anything drastic. With the Jupiter having a different woofer to the Mercury, Venus and Saturn it means locating a second-hand one could be tricky as they are pretty rare speakers!

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Old 12th Feb 2019, 12:49 pm   #2
cathoderay57
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Default Re: Tannoy Jupiter J40 Tweeter Repairs

Hi there, well done and yes I did a similar repair on a pair of Infinity RS4001 tweeters. Still working fine after 6 years on my Quad IIs. Spookily I have just done a fine wire repair on a large elliptical from a 1954 Graetz Sinfonia 4R AM/FM radio, see here: https://www.vintage-radio.net/forum/...d.php?t=153790 The advantage of fixing the tweeters is that sometimes you can get at the coil with a reasonable amount of care, whereas the elliptical required cone removal and so there were alignment issues to worry about after the repair as well. Cheers, Jerry
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Old 12th Feb 2019, 1:36 pm   #3
Edward Huggins
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Default Re: Tannoy Jupiter J40 Tweeter Repairs

That's interesting - I did not think that Tannoy ever did use OEM drive units?
And back in the 1980s, they were probably far a more vertically integrated company than they are now.
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Old 13th Feb 2019, 7:25 am   #4
Diabolical Artificer
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Default Re: Tannoy Jupiter J40 Tweeter Repairs

The Seas H253 are not ferro fluid type tweeters, I've seen this asserted several times in relation to repairs of Mission 720's. I think everyone who research's these old Seas tweeters comes across the same incorrect post or thread somewhere.

Well done on the repair, I've repaired several in the same way without any noticeable difference or degradation of sound. It's a fiddly job, especially scrapping off the wire insulation of the broken end/s but well worth it.

Andy.
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Old 13th Feb 2019, 8:51 am   #5
Ted Kendall
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Default Re: Tannoy Jupiter J40 Tweeter Repairs

The standard trick with a scraping voice coil is to re-mount the drive unit upside down - frequently works and saves a lot of fiddling.
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