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Beolab 4 repair , fix it, bin it,It's worth it ??

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marexy
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marexy posted on Tue, Sep 3 2019 7:19 PM

but what  IF ..

 

 

 

First of all, I welcome all forums members and users of that  and ozhers B&O products.
Like many of you, I purchase quite a few units during years and after some time some of them needs attention. some more some less..
But most of all, I want to bring to life the Beolab4 speakers.

As my darling wife like to listen to them in office :)

Why 4 broken pcs. Ok…2 of them I purchase from collegue and they work for 2 years then die…ende, vege, game over


And than I purchase oline 2 in perfect condition…yap…you wish…one work for one month and the other for 3 month..

 

And the reason of course....taaadaaaa

 

 

 

 

The amplifier board is defective in all of them.
This is also the reason for 95% (or meore) off all errors on these speakers.


Let me highlight the purpose of this post.
Simply, an astronomical price for a spare part that is over € 100 a piece.
With an official B&O service shop 130€ + labor which I find shameful for such a small piece of electronics PCB board.
A friendly user and a true expert on these forum offered me a reasonable price, but it is still too high and un- economical for me.
Let me clarify.

It is not economical to repair on component basis, for customers, because it is too time-consuming and you can not give as much warranty as for new one plus you can not firnd original MOSFET ST9F3LL any more.

In addition, you can actually buy a pair of used working speakers for around € 150. to 250€ .so the same price as spare PCB amplifier borad.

So the repair is not theoretically and economically worth if you not do it for your selfe.
But since electronics is one of my hobbies and relaxing my nerves after a busy day at the company, it will be a bit of a challenge for me to have a little education and a joy to repair. In this modern world where repair is already economically unacceptable, I find all this sad.
Everybody throws away things that can actually be fixed ( ok..some more some less )
I will write this post in stages as I find the time, the moment of inspiration, and the spare parts.
I also hope for your help if you have any broken PCB’s to donate for my experimentation :)

You can find 2 photos of that PCB.

on fist photo you find  some sound processors and on the other MOS transitors that are usuly faulty.

also 10 ohm resistor is damaged and some transistors in the area.

I did fix some of that power boards to my friands but i can not be 100% that they work for long time.



 

 

 

 

 

 

 

 

 

 

 


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crossbytje
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Hi!

I posted yesterday in another beolab 4 repair thread, but figured it might be good to alert the people who posted here too.

My Beolab 4 PC went bad yesterday, sudden high pitched pulsing sound, afterwards, a low buzz and faint red led pulsing. No sound anymore.

Could someone point me to where I can find a replacement board for the speaker? Should I just query the dealer? What exact name should I use for the board? 

Not sure I'd try the repair myself, would have to get the right tools for the job..

Thanks a lot!

Beolit 12 - Beolab 4 pc (dead now) - Beoplay H5 - Beolab 9 - BeoRemote One BT - Beoplay M3

marexy
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Hi

99% you have broken amplifier board.

It's 7x5 cm PCB board and at our delaer price is 130€

You can chenge it in 20 minutes if you know with tools.

Can be repaired but , if you have local delaer who can do it for 50€.

For app..200€ you can buy used pair BL4 ...so do the math :)

 

 

crossbytje
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I don't know where you're looking, but I can't find a pair for €200.

It is indeed quite expensive, bought my Labs for €400 a couple of years ago. I expect the other one to go bad too in the future :-(. This can be said about the replacement pair too, If I spend at least €300 for a new pair, and they fail as well, then I'm just collecting broken lab 4s..

I'm really sad to see them go, and will need to get something else as PC speaker set. Lab 3s are too expensive, and overqualified for the job. Beoplay S3 looks terrible imo.

I'll ask my dealer what his price is for a new amplifier board.

Beolit 12 - Beolab 4 pc (dead now) - Beoplay H5 - Beolab 9 - BeoRemote One BT - Beoplay M3

marexy
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ok..my bad...form 200€ on..to 350€ yu can find it on Ebay if you wait for aucion end.

Last time i check at my delaer price were 140€ pcs. Yes it's much to expencive.

And if you take it to original service you pay 30€ extra for work.

So i decide to rapair it my selfe and i did with all my 4 amplifier boards.

It did take some time ( app 20 hours )  but i learn so much in these process :)

Can not say that it will work 4ever..but they are working fine for a few month now.

 

 

 

crossbytje
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So I found a single beolab 4 on the net which should arrive any day now. (At least if I'm not being scammed..)

What I noticed when opening the lab 4s is that the bass port was filled with foam on both my speakers. Is this normal? It seemed strange, but I bought them from a dealer, so I guess they were not tampered with.

I wondered now, since it is dead. Would it be possible to transform it into a passive speaker? My home theatre is setup using a Marantz AVR with preamps to my Lab 9s, I could maybe use the 4 as a center channel..

Beolit 12 - Beolab 4 pc (dead now) - Beoplay H5 - Beolab 9 - BeoRemote One BT - Beoplay M3

crossbytje
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Today arrived my 'new' speaker. Unfortunately, when I powered it up, I got nothing more than the same pulsing sound Sad.

The search continues. 

Is there somewhere a how to available on how to repair these boards and what components are needed? I may try it out. In these corona quarantine times, I could use another distraction.

Beolit 12 - Beolab 4 pc (dead now) - Beoplay H5 - Beolab 9 - BeoRemote One BT - Beoplay M3

Xocas
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Xocas replied on Thu, Jun 25 2020 6:24 PM

Hi. B&O has replaced the class D amplifier board ( P/N:  8003563 ), that was included in the Beolab 4000 MKII active speakers, with this other P/N: 8003195. Both pc-boards look pretty much the same, like the ones in the photos posted in this forum entry. The most obvious difference being that B&O  has changed the mosfets that were being used as drivers for the twetter and bass speakers. They do not use the obsolete STS9NF3LL anymore; it has been replaced by the much more powerfull n-type mosfet FDS6294, so the new 8003195 class D amplifier boards can be assumed less prone to failures than the older ones.

I will say that the FDS6298 n-type mosfet could also be used instead, as it is a "better", or newer,  version of the FDS6294 with a smaller  RDS on (9 mOhms at Vds 0 10V). Both FDS mosfets (FDS6294 and FDS6298) support 30V drain-source voltage and 50A of (pulsed) drain current with the other electrical characteristics needed for a good switching mosfet used with PWM controllers, as it is the case with these class D amplifiers.

I just bougth one of this new pc-boards p/n: 8003195 from an official B&O dealer here in Spain (Madrid) for an amount of 49€ (plus 10€ delivery cost for spanish delivery addresses + VAT). They sent to me a completely new board, that they ordered to B&O Denmark, in less than four days. I can say that their service and attention was really good and kind. I replaced the amplifier board of my failing unit and now it works fine.

I found that the failing board had one of the old STS9NF3LL mosfets in the twetter section shorted (TR106 and presumably his "companion" mosfet TR105), also one smd transistor acting as driver for the mostefs had it's base-emitter shorted (and presumably the companion transistor) and one 10 ohms smd resistor connecting to the gate of mosfet TR106 was open.The symptoms of the fault were an audible high frequency oscillation in the twetter (reflected with much less volume in the bass speaker) with no sound reproduction, and the +12V and -12v voltages falling down to about 10.5 volts.

I will try to repair the board, but considering the skills needed to repair smd components, the tools needed, and the fact that you can get a new 8003195 amplifier board for less that 75€, all costs included, I will say that this work is not worth it... unless just for fun !!.

 

Xocas
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Xocas replied on Fri, Jun 26 2020 6:59 PM

Hi. I duplicate the text I have posted in other blog entry,  just in case may be useful here...

 

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