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

47 replies
MA
marexy
Silver
785 posts
Posted September 3, 2019 at 19:19 GMT
#2127449

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.



 

 

 

 

 

 

 

 

 

 

 

MA
marexy
Silver
785 posts
Posted September 3, 2019 at 19:25 GMT
#2127450

PCB mosfet side

MA
marexy
Silver
785 posts
Posted September 3, 2019 at 19:31 GMT
#2127451

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.

 

 

 

 



 

 

 



 

JV
jvezina
Gold
260 posts
Posted September 3, 2019 at 19:53 GMT
#2127452

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

 

My B&O Icons:

Beoremote-Beo4.png Beoremote-Beo4.png
Beovision-Eclipse.png Beovision-Eclipse.png
Beotime.png Beotime.png
Beoremote-One.png Beoremote-One.png
Beoplay-A1.png Beoplay-A1.png
MA
marexy
Silver
785 posts
Posted September 4, 2019 at 07:58 GMT
#2127453

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.

MA
marexy
Silver
785 posts
Posted September 4, 2019 at 08:01 GMT
#2127454

and other side

DI
Dillen
BronzeModeratorFounder
12777 posts
Posted September 4, 2019 at 13:06 GMT
#2127455

I wrote about this level of service a.o. some time ago.
Mainly in danish but Google is your friend..

MA
marexy
Silver
785 posts
Posted September 4, 2019 at 13:32 GMT
#2127456

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 :)

 

 

MA
marexy
Silver
785 posts
Posted September 23, 2019 at 19:33 GMT
#2127457

ok..let's go on

on these WWW site you can find  interesting data.

link

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.


 

 

 

 

JV
jvezina
Gold
260 posts
Posted September 23, 2019 at 21:31 GMT
#2127458

marexy wrote:

ok..let's go on

on these WWW site you can find  interesting data.

link

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!

Jean

 

My B&O Icons:

Beoremote-Beo4.png Beoremote-Beo4.png
Beovision-Eclipse.png Beovision-Eclipse.png
Beotime.png Beotime.png
Beoremote-One.png Beoremote-One.png
Beoplay-A1.png Beoplay-A1.png
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