Beovox 3702 Restoration

33 replies

Hi All,

I recently obtained a Beomaster 3000.2 and a pair of Beovox 3702. The beomaster and the speaker cabinets are in great shape, but the woofers are completely rotten. They make a scraping noise when moving the cones and the foams are completely gone. I wish I could post pictures, but since recently it seems I cannot post pics anymore on this forum - the menu that comes up when trying to add a pic seem to have changed and only allows to add a URL link...me very sad! Anyway, I am wondering if there are some modern woofers that can serve as a worthy replacement? Any input is welcome!

Thanks!

Rudy

 

If only the foam surrounds are gone you should be able to save them and while open change caps in the filters.

Location: Mexico city

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Hi Soren,

The woofers are in really bad condition. There is significant scraping noise when trying to move the cones...

with regard to posting pics, somehow all the relevant icons are gone on my mac/Safari/Firefox. I used to be able to post pics, but no more...probably some browser compatibility issue...

Rudy

Hi Rudy, I run firefox myself and no problems.

Lately we had some 3702s with strongly bend spiders, that may be your problem, if the foam is all gone and the cones free from the basket there should be no scraping, are the dustcaps in place ? if not you may have dirt in the voice coils. Here a some pics of my 3702s

Location: Mexico city

Retired
Printing machine technician
Restored various 1960-70 items
Rock and Roll music
Collecting Vinyl
Restored Jukebox Wurlitzer 1050

O.k....maybe I still can upload pics...sorry for the confusion:

I tried moving the cones again. It seems if I hold them very steady, I can move them a few mm without getting the scraping noise. The orange bellows below the paper cones seem to be in good shape. The coil section is also lookin good...

The mid/treble speakers of that speaker are also very dirty (or rather 'hairy' - this speaker must have lived for some time in the garage with dogs or the like...;-). The other speaker, which had its cover still on has no hair, but the midrange speaker is sticky, like the lacquer on the cone has chemically degraded a bit. Is that normal?

Pic of mid/treble section:

Rudy

My midranges was "sticky" and dirty too, I cleaned very carefully with mineral spirit, and left for a day, now they are clean but still a little (very little) sticky, the Tweeters after cleaning OK.

For your bass drivers, clean of the foam, all of it, when clean, try to move the cones again, three fingers centered around the dust cap, and move exactly centeret, we have to be sure that the coil is OK. If it still scrapes you will have to yell, HELP MARTIN, MARTIN🤔. There may be dirt in the voice coil behind the dust cap. When the driver is clean, make a pen mark at the base of the dust cap, then cut it as near to the cone as you can, the pen mark is to get in the same position when glueing it back again. Hold the driver upside down and try to clean with blow air, by a can if you dont have a compressor, if it still scrapes, get piece of plastic film 10x70 Mm 0.1 to 0.3 Mm thick, put that in and turn it around in there a couple of times. My drivers has holes in the cone between dustcap and the spider, use blow air there too.

I'm not sure, but IF the coil is damaged it should be posible to check that with an Ohm meter, connected across the coil it must show a difference when the scraping occurs. Any way with the leads disconnected you should get the same reading from both drivers, I will go check both of mine and come back with the values.

THe paper cone in the pic is kind of bend, you can get that one back to shape by wetting it, where the bend is, with water mixed with mineral spirit and then form it back in place and leave to dry.

Location: Mexico city

Retired
Printing machine technician
Restored various 1960-70 items
Rock and Roll music
Collecting Vinyl
Restored Jukebox Wurlitzer 1050

I took the woofers out and cleaned them as good as I could. The loose remnants of the foams are gone. I tried to move the cones with the 'three finger method'. It seems I can move them without scraping. The orange dust caps are in good condition on both and are not perforated. I measured the resistance. Both have 3.9 ohm. The voltmeter shows a few mV when I tap the cones. Seems the coils may be o.k. 

I am wondering what the best method is to get the glued parts of the foams off the cones and the metal frame? Where can I get fitting foams?

Thanks much in advance!

Rudy

I by surrounds link, the 8" is the right one for my drivers, but check the outer and inner D on yours before buying. First I did was S45s 1.5 year ago, still no problems. My surrounds is Outer D 7 3/4" (196 Mm) inner D 5 1/2" (140 Mm)

I do like this

3.9 ohms is OK I get 4.1/4.0 at mine and yes mV when moving.

On the basket I use Iso alcohol or acaton, and scrape, dont let alcohol or aceton get on your cone, on the cone scrape with a sharp hobby knife (cutter), you don't have to get it all of, just the foam, and get it down to more or less even surface, AND LEAVE THE DUST CAP ON, until it is time to shim.

If you order new dust caps chose a little bigger than the one you have, if not, just cut the old one very close to the cone and glue it on again after test drive.

 

Location: Mexico city

Retired
Printing machine technician
Restored various 1960-70 items
Rock and Roll music
Collecting Vinyl
Restored Jukebox Wurlitzer 1050

Hi Soren,

This starts sounding like an exciting little project!! I wondered about alignment immediately after realizing how sensitive the scraping is to the alignment of the cone! I went to the foam seller's ebay store. I think the foams you selected fit my speaker's dimensions, too.

It seems that the dust covers are sold in 1/4 inch steps. The caps installed in my speakers are 2 1/4. Does your statement about getting "little bigger" ones imply that I should get the 2 1/2 inch ones?

Where on their radius exactly do you cut the old dust covers out. I noticed that the wires enter the driver part on the outer boundary of the covers...

Thanks much for your advice!!

Rudy

Cut the dust caps as close to the cone as you probably can, make a pen mark before cutting, then its easy to get them in the same position when gluing them back on, just put a small amount of glue to cut on the cone, take the cut of cap and place it pen mark to pen mark with a little pressure, done, let dry. If the wire connects are close to the dustcap, I recommend this action.

Location: Mexico city

Retired
Printing machine technician
Restored various 1960-70 items
Rock and Roll music
Collecting Vinyl
Restored Jukebox Wurlitzer 1050
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