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Beolab 4000 questions - foam rot

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h1npw
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West Bridgford, Nottingham.
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h1npw posted on Sun, Mar 5 2017 2:06 PM

I'm looking to buy a couple of pairs of these great speakers from flea bay... Can anyone tell me 

1) How can you differentiate between those with the black foam inside them that eventually turns to goo, and those with the "stable" white foam, without asking sellers to take their speaker to bits?

2) Did they change the foam when they started production of the Mk2?

3) Did the serial numbers continue in sequence from Mk1 to Mk2?

4) is there a specific serial number point when the foam changed?

Any info will be greatfully received!

Cheers

Nigel

 

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h1npw
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West Bridgford, Nottingham.
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h1npw replied on Wed, Apr 22 2020 12:01 PM

Hi Umanja & welcome to Beoworld

The problem with the internal foam of the 4000s is that over time it turns into a sticky, gooey substance which causes shorting in the electronics. Even if you clean all the substance off the circuit boards (which is easier said than done) the damage has already been done....The repair costs of fixing this is probably more than a replacement pair of speakers. If you can get your money back on your purchase I would do so, if not, take out the tweeter and woofer and either keep them as spares, or sell them on ebay. Both drivers were used in other Beolabs.

Cheers

Nigel 

Just a note, Ive had a pair of 4000 for a couple years and was worried Id have the rot as well.  I checked and my unit serial starts at 15 and it seems the rumours were true... white non-rotting foam! 

--

BeoLab 18's. Beolab 3's. A8. A9. A2. H7.

Evan
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Evan replied on Fri, Jan 14 2022 11:59 PM

After a very impulsive evening on flea bay, I now have 3 MK1 BL4ks (Type 6638).

Serial numbers:
14933945
15456673
17375386

All with white foam. 

Random, nerdy transducer note: Even though they are all MK1s, there is a difference in the tweeter heatsink.

SN 14933945 + 1546673 tweeter:

SN 17375386 tweeter:

Beo4 'til I die!

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