ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
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..
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.
PCB mosfet side
Regarding some fault indicator..
If the spekaker is defective and make pulsing sound than you have 30% chance to fix it.
IF the spekar have bad- muffed , distorted sound and bass driver is pushed in or out ..than you have 10% chance for repair.
That is my experiance...maybe or. .. I am sure ...some forum members have way more success and experience than me.
From my experience , most of the errors are on the woofer part, followed by distortion on both channels, and then error on the tweeter part.
I own a pair of Beolab 4000 MkII and they have exactly the same amplifier boards. After 10 years, they start to make a loud scratching noise, as if there was a bad contact in them. I have the amplifiers replaced but I kept the defective boards. I will try to repair them as a hobby and keep them as spares as there is nothing to lose.
Which components have to be checked and eventually replaced? The 10 ohm resistors and the MOSFETs?
There is no schematic so the repair has to be done by trial and error.
Is 9F3LL the official part designation? I checked in the ST Thomson (the manufacturer) web site and I wasn't able to find a MOSFET with similar identification.
Thanks in advance,
Jean
Interesting story. A colleague of mine has a friend who take for repair a pair of Beolab 4 speakers to an official B&O repair shop. Because the cost of repairing and replacing the new parts was too high, he said that he would take the speakers back and sell them as broken. The next day he came to pick up speakers.
Coincidentally, I met this person few month later and offered that i look at what I could check or fix as a second opinion and as a favor to a friend. When I opened the unit, I was very surprised. That's how PCBs look when I take them out of the speakers. To me, the way that the official B&O repairer returns such plundered parts of the unsuspecting client I find very low. He probably kept the existing ones for himself, but installed back ones that are total garbage. A really bad experience and an even worse commercial for this brand and this repair shop.
and other side
I wrote about this level of service a.o. some time ago.Mainly in danish but Google is your friend..https://archivedforum2.beoworld.org/forums/p/7854/69582.aspx#69582
Martin
100% aggree with you.
I's shame that some official B&O repair shop do that kind of dirty practice.
So i try to give my best to fix some boards.
any of your " hint " is welcome :)
ok..let's go on
on these WWW site you can find interesting data.
https://ham.brugtgrej.dk/forum.php?mode=thread&obj=68196
Did some additionla repair and did fix one board with STS7NF60L mosfet BUT...it's overheating and FET going to 106 degree in 3 minutes when playing.
marexy: ok..let's go on on these WWW site you can find interesting data. https://ham.brugtgrej.dk/forum.php?mode=thread&obj=68196 Did some additionla repair and did fix one board with STS7NF60L mosfet BUT...it's overheating and FET going to 106 degree in 3 minutes when playing. for test ..I switched back for the original ones and the overheating is gone. therefore, are not correct FET components or some elements need to be replaced before the FET transistor.
Thanks a lot!
Now i do have some problems as i have no additional PCB's for more testing and trying to find best way and alternative to fix different errors on that PCB.
So if any of you have faulty, broken, not working or partial working PCB would be happy to buy or if you wish to donate them for ""for scientific purposes"" :)
My shipping costs.
If any of you wish to repair it by DIY you need SMD heat gun + smd soldering iron with reguleted temperature.
With some effort I was able to repair one unit and it has been playing successfully for 3 days. I advise you not to go into repair without at least a basic knowledge of electronics.
Hi Jean
Yes...bl4000 Mk2 have the same boards.
There are no PCB Shematics....as i know of...
Maybe some inside B&O info will help...hmmm
In 50% ...maybe 50%... it is ok to change mosfet ST9F3LL but only with the same one as till now i did not find any other option to work and all 4 per clanalle should be changed. And i do not have datasheet for ST9F3LL.
10 ohm change if broken...no need if it is ok.
In many cases there are faults on the top side of board or bad connection inside board. Note....Repair only with correct smd tools.
any other questtion..PM me
marexy: Hi Jean Yes...bl4000 Mk2 have the same boards. There are no PCB Shematics....as i know of... Maybe some inside B&O info will help...hmmm In 50% ...maybe 50%... it is ok to change mosfet ST9F3LL but only with the same one as till now i did not find any other option to work and all 4 per clanalle should be changed. And i do not have datasheet for ST9F3LL. 10 ohm change if broken...no need if it is ok. In many cases there are faults on the top side of board or bad connection inside board. Note....Repair only with correct smd tools. any other questtion..PM me
Thanks a lot for your very valuable advice!
Also, should I replace all ST9F3LL mosfets, or once the defective one is found I can leave the others in place? Are they failing because they don't age well or because they are used near their limits?
Regards,
I think the correct FET's devicename is STS9NF3LL
https://www.st.com/resource/en/datasheet/cd00002691.pdf
But they are obsolete...
hx
B&O has switched from STS9NF3LL to FDS6294 in later production of the pcb
Hi
Try to change only bad one but ...it is better to change all 4 on the same side.
Hemenex ..thanks
Yes it is correct datasheet.
If you check item TS7NF60L it is not so differnt but it is not ok ..as heating badley fast.
If you put finger on ti when speaker is working and it is open...you can feel it, so from my point of wiew it's not safe to use it.
There are some WWW pager that offer "" original" parts ..but i tihk all are fake.
""Also, should I replace all ST9F3LL mosfets, or once the defective one is found I can leave the others in place? Are they failing because they don't age well or because they are used near their limits? ""
Yes ..maybe they are used near their limits..can't say without shematics and correct service manual.
Or just generaly poor design of PCB from start.
plus i'm not el.rapir geek to be smart and i can give only my point of perspective.
i learn much on these project :)
It's not over yet as.. will try different end-mosfet and some other tweeks log the way.
all done :)
Beolab 50, Beolab 8000 x 2, Beolab 4000 x 2, BeoSound Core, BeoSound 9000, BeoSound Century, BeoLit 15, BeoPlay A1, BeoPlay P2, BeoPlay H9 3rd Gen, BeoPlay H6, EarSet 3i, BeoVision Eclipse Gen 2 55", BeoPlay V1-40, BeoCom 6000 and so much else :)
i think...it's 85% the same as BL4 or BL4000NK2 board
try to check resistors closest to M3307 / 8pin chip and check 2 mostet transsitors in the same area.
If that is ok..check all resitors in the board.
marexy: Hi i think...it's 85% the same as BL4 or BL4000NK2 board try to check resistors closest to M3307 / 8pin chip and check 2 mostet transsitors in the same area. If that is ok..check all resitors in the board.
Hello Marexy,
What do you mean with check them? I found that the PCB is called "35" or 8004783 anad that the Beovision 11 has the same boards. It seems to be an iteration on the BL4 and BL4000mk2 amps. I would like to try and change to use the other channel that probably isnt faulty. Do you think that could be possible and if so, which pins should I rearrange? It seems FP1,2,10 and 11 on P1 is connected to the main logic board, as is the free cable connected to P3.
Michael:I managed to make it work! I measured all the pins and some other things to figure out what they do. Then I simply switched pin 1-11 and 2-10 on the input. And moved pin 1->3 and pin 2->4 on the output to make use of the input and output that was before unused. It seems to work perfectly! I’ve been doing some tests and it all is fine and sounds lovely. Why the other amp channel started distorting is something I will leave for now and I’ll re-assemble the tv again tomorrow after some more tests. Thanks for the advices here too!
Just to give an update on this issue.
I decided again to go the easy way and I had the board replaced as they are still available from B&O. Nevertheless, I bought replacement ICs from Digikey as spares as they are still available from them even if they are obsolete. If the amplifiers fails again in the future and are no longer available from B&O, then I will try to repair them.
The official part number is indeed STS9NF3LL and the chip is marked 9F3LL as the others before.
Marexy, if you have time, could you write a short step by step procedure explaining how to diagnose the problem on the board and upload it to the service manual section of the forum. I did the same a long time ago about capacitor replacement for the North American MX 5000.
Best regards,
Thanks a lot,
Hi all, coincidentially, i am also working on those now.
I kept defective in the past and have 5 now.
All had other defective components apart from some fets: resistors (the big and/or small 1K5 apart from the 10R) and even smd transistors on the opposite side of the fets.
Anyway, the challenge still is the fets.
With a bit of luck the replacement module is still available for around 60 euros (that used to be the price here) and i hope to see if the newer types use the FDS6294 fet as a direct replacement.
On a Dutch general repair forum there is also someone working on this, let's see what we can figure out....:)
If you decide to sell PCB's let me know :)
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..
Beolit 12 - Beolab 4 pc (dead now) - Beoplay H5 - Beolab 9 - BeoRemote One BT - Beoplay M3
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 :)
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.
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.
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..
Today arrived my 'new' speaker. Unfortunately, when I powered it up, I got nothing more than the same pulsing sound .
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.
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 !!.
Hi. I duplicate the text I have posted in other blog entry, just in case may be useful here...
Have a pair of beolab 4000 mk2 where one has intermittent static noise. Opened it and had a look at the amp boards then switched em to see if problem vent to orher speaker. Problem moved with the amp. The amp with the problem has a solder spot on the ring with two copper wires that is diffrent from the 7 other solder spots. This one has slot more solder on it and theres signs of what looks like melted traces in pcb close to it. Could this be the culprit? Is it fixable or should i just order new amp board? Ive added pictures in the media section. Named ‘ Beolab 4000 mk2 amp board 1/3, 2/3, and 3/3’.
Send ma a PM..pls
I do not see photos.