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.
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,
Jean
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 :)