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.

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

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.

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 here, 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.

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.

The fog is lifting...;-) Thanks much for your great explanations! I am wondering about the 'shimming' procedure that you mentioned in Pepps' thread. Is the gap marked with the arrow where you shim with the plastic strips? (Pepps: I hope you do not mind that I borrowed your pic - thanks for posting it! - I like to look at things before whipping out the carpet knife...;-).

HarryPierce:

Is the gap marked with the arrow where you shim with the plastic strips?

Exactly right, be very careful with the shimming part, its important to get the same amount of strips at all 3 points, and all strips all the way to the bottum of the gap, therefore I allway cut the strips to the same length, and check that the cone moves in and out a little harder than free.

The check with a 0.1 Mm strip, where the cone moves hard with the 0.1 inserted at one point, and nearly freely when not there, is the best way to check it, take your time shimming.

Got it. With regard to glue, is the sticky glue you mentioned "Aleene's Original Tacky Glue"? Seems there are a variety of Aleene's out there.

On a different note, can you recommend a good source for the capacitors in the crossovers?

Thanks!

HarryPierce:

Got it. With regard to glue, is the sticky glue you mentioned "Aleene's Original Tacky Glue"? Seems there are a variety of Aleene's out there.

On a different note, can you recommend a good source for the capacitors in the crossovers?

Thanks!

Glue yes, I have been surfing the US and it gets expensive, or they screw you on shipping, at least down to Mexico.

The best one in the US I think is Here, dont go for the expensive audiophile caps, the cheapest ones you can get are better than the ones Beo used 40 years ago. I'm still waiting for my caps from Martin he shipped middle of December, but sometimes it takes 6=8 weeks to get here, or it got stolen somewhere.

If you cant find he right value go for the nearest, the Beo ones are +- 20 %, so no problem.

If you order from Martin, be sure to give him the type and series of your speakers, mine is Bvox 3702 ser. 6233, the other series is 6244

I ordered everything...I will report back about my experiences with this project. I hope you will get your parts soon!

Rudy

HarryPierce:

I ordered everything...I will report back about my experiences with this project. I hope you will get your parts soon!

Rudy

Done for the day ?, come to Evans Party Here

Yes that is another 'party' for me, too...recapping the humming 3000-2...

HarryPierce:

Yes that is another 'party' for me, too...recapping the humming 3000-2...

The easy way, is to get a cap and lamp kit from Martin, before that open the unit and check the trimmer and order these too.

The problem with the 3/4000 is the front, its a PIB to get off and on.

I thought I would post an update about my 3702 project: I basically followed Soren's advice. First I removed the old foams as good as I could and cut off the dust caps:

The next step was to glue on the new foams (I used the ebay store Soren recommended - very fast and nice quality). Here it was important to not put too much glue on the foam. One wants to avoid that a significant amount of glue gets squeezed out from inbetween foam and cone since this can get messy. I had to remove the foam the first time and take 50% of the glue off, then put it back on:

Attached to cone. I simply pressed the foam on the cone going around the cone again and again and pressing them together. After ~5 min the foam remained stuck down (less glue works better...)

The next step was shimming. It turned out that laser printer transparencies are perfect. These woofers took two strips (~0.13mm thickness) in three locations. After putting them in the speaker cone was almost immobilized, but would still move if pushed.

Next step: Glueing the foam to the cage. Here I used a perfectly matching dinner plate to hold it down during drying:

One day later, I glued the dustcaps back on. A thin layer of glue does it (glue is still white in the pic):

On to the cross overs (again followed Soren's advice, and bought from Parts Express; a nice experience):

Here the old crossover:

And here after cap exchange:

I tried to match the original capacitances as good as possible, i.e. I used some combinations in parallel, since the original values were not available.

Strange thing: The original caps seemed to have been mostly ordinary polar electrolyte caps. I guess one can make an argument that that may work since the signal is mostly true AC without DC component, i.e. the electrochemical dissolution of the electrodes under reverse bias should reverse itself during the next halfwave at opposite polarity...I measured the ESR and capacitance of the old caps. Most seem to have survived well...all except the 12uF ones were at spec.

The next step was cleaning off the doghair from the sticky midrange speaker (quite a mess!!). Ethanol finally did it, but most of the sticky laquer came off in the process:

I am wondering if I should leave it like this, or paint them again with some glossy black??

I still did not put the woofers back in. I am discussing right now the philosophical question whether to insert cable terminals into the back panel of the speakers or leave everything original with the cables directly soldered on to the crossover...Right now I am leaning towards the terminals and using nice modern cables.

HarryPierce:

I still did not put the woofers back in. I am discussing right now the philosophical question whether to insert cable terminals into the back panel of the speakers or leave everything original with the cables directly soldered on to the crossover...Right now I am leaning towards the terminals and using nice modern cables.

I would go for the terminals, all other speakers I have repaired has terminals, and its a lot easier to get the drivers out with terminals.

I didn't get my caps from Martin yet, so I could not preceed, Parts Express wants me to buy for at least USD 50.00 and then they charge me more or less the same for shipping to Mexico, so I will just have to wait until I get up there, or try again with Martin.

Now please get on with it, I'm real curius abaut the result.

About the old caps, they are bipolar, but just marked with plus and minus, because in some positions they use the shield as ground connection.

About the lacquer on the mid range, there are some special brands out there, but I dont know anything about it, so maybe another member could give some advice about it.

Very good job and lovely pics. Congrats

Rudy, took a look more on this pic. The "tube" around the coil has a bend at the top, and as these drivers has a long pull, this may give "scrathing" when having a lot of bass or plaing very loud. I know its bad news, but try it out before you start taking of the dust cap again. And dont kill the messenger

Rudy, on your shimming pic I see that the "tube" around the coil has a bend in it, as these drivers has a long pull, this may give distortion or "scraping" when adding a lot of bass or plaing very loud, test it before taking of the dust cap again. And dont kill the messenger

Søren Mexico:

About the lacquer on the mid range, there are some special brands out there, but I dont know anything about it, so maybe another member could give some advice about it.

I don't think it needs anything. Certainly not paint! That would increase the mass of the cone a lot and it wouldn't sound the same any more (and so will a handful of dog hair ).

The special coatings are usually there to stiffen the cone or to repair/prevent rips. It think Visaton is one brand, perhaps you can find the marketing material somewhere and decide if it would be useful in this case.

The dent in the tube only goes about 3 mm down....do you think this is really a problem? Seems really hard "party operation" would be necessary to cause scraping...I tried to bend the dent back out, but the material is quite elastic, and I was afraid I might distort the overall shape of the tube...

HarryPierce:

The dent in the tube only goes about 3 mm down....do you think this is really a problem? Seems really hard "party operation" would be necessary to cause scraping...I tried to bend the dent back out, but the material is quite elastic, and I was afraid I might distort the overall shape of the tube...

 

As it only goes 3 Mm down I dont think it will be a problem.

BTW can you post the caps and resistor values from your crossover, I think they are diff. from mine.

I have left to right, 5 uF, 25 uF, 75 uF, 12 uF, 75 uF