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Beolab 5: [FIXED!] noises when using the remote control. (dead diode on PCB6)

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JayBL5
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JayBL5 posted on Tue, Nov 3 2020 8:38 PM

Hi Everyone!

One of my 10+ year-old BL5 started making noises (especially when using the remote) and my local B&O agent told me there's no more chassis replacement or only a few second hand at more than double the regular price (and they won't take back the faulty one), so I decided to give it a shot myself and after investigating, I found the culprit.

An SMD zener diode on the PCB6 (primary side) of the Switching Power Supply is dead. As an idiot I forgot to write down its part number before closing the BL5, but I remember it's D200 or D220. It is right under the rectangular rectifier (solder side) on the primary side of the PCB6.

Would you, by any luck, know what value it is? I could open the other BL5 to check, but it's a real pain to access that area.

Thanks a lot! Appreciated!

Jay

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Dennis
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Dennis replied on Tue, Nov 3 2020 10:42 PM

Hi Jay,

Welcome to BeoWorld! Smile

Nice job tracking down the culprit! There's very limited information on the internet when it comes to repairing BeoLab 5s, so you could be one of the pioneers if you make a how to thread! I'm sure a lot of people would be very grateful and interested in following your progress. We love photos on Beoworld btw... Big Smile

In line with what I mentioned above, I'm afraid you will have to open it again to check. As you may know, Bang & Olufsen haven't published any schematics for BL5 - only service manuals on how to diagnose which board to replace and how to dismantle the product in order to do so. And the B&O servicetool that enables you to read out faults etc. is only available for dealers. These factors combined with the value of the speakers, are probably the reasons why you won't find repair infos from DIY'ers. 

As you were probably informed, a replacement chassis from B&O will set one back around 1000€, so if it would be possible to found a database with detailed descriptions of faults and solutions, it would enable the skilled DIY'ers to repair these speakers on a component-level. I could imagine, that it's usually some specific components, that give up the ghost, as the BL5s seem to have quite a high failure rate and often the same symptoms. 

/Dennis 

JayBL5
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JayBL5 replied on Tue, Nov 3 2020 11:04 PM

Hi Dennis, thanks for the welcome!

Chassis on that one has been replaced three times already (twice for the other one) and that's the reason I'm giving up on paying double the regular price to get it replaced a fourth time knowing it will fail again in a few years.

I'll open it again (probably this weekend and will take detailed pictures with an explanation of the symptoms).

B&O should really release schematics for products that aren't supported anymore. It's really unfair for their loyal customers to end-up with dust collecting pieces of art.

Jay.

Beobuddy
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D200 is a bridge rectifier on the component side. On the solder side there 4 identical smd diodes, SS36. Just simple fast switching diodes.

stefan
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stefan replied on Wed, Nov 4 2020 11:25 AM

JayBL5:

..... and my local B&O agent told me there's no more chassis replacement or only a few second hand at more than double the regular price (and they won't take back the faulty one),....

Jay

I can`t believe, your dealer told you that!

My experience is, that in case of a faulty BL5, the dealer orders a 'repair kit', which is basically the complete electronics of a BL5 and replaces your faulty one with the 'new' electronics. Your faulty kit will be sent back to Struer and be repaired in the factory, waiting there for the next order.

Stefan

Beobuddy
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stefan:

My experience is, that in case of a faulty BL5, the dealer orders a 'repair kit', which is basically the complete electronics of a BL5 and replaces your faulty one with the 'new' electronics. Your faulty kit will be sent back to Struer and be repaired in the factory, waiting there for the next order.

In theory that would work. But it happens that some boards can have severe damage which simply aren't repairable anymore. At the end of the processorboard, there is the protection part, which comes after thew ICE Power boards. Some of these boards can have so much damage that replacing by another (new) board is the only option. What happens when these specific boards aren't available? The balance between the amount of received and refurbished/fixed chassis will become a problem.

 

oli
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oli replied on Thu, Nov 5 2020 4:47 PM

They are of course still available. Beolab 5 is end of life since 2017 or 2018. All these Final Edition series are still under warranty today !

oli
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oli replied on Thu, Nov 5 2020 4:47 PM

.

kawo
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kawo replied on Thu, Nov 5 2020 8:45 PM

the chassis is still available, one of my 2007 BL5 is also faulty, the repair shop ordered a refurbished replacement chassis from the factory. Only downside in the moment long lead time, they expect the spare part mid of December ... 

I got a quote below 700 Euro for the chassis plus roughly  1 hour labor  time to replace it onsite. I was surprised in a positive way as I also heard quotes north of 1000 Euro just for the part.

JayBL5
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JayBL5 replied on Wed, Nov 11 2020 4:57 AM

Ok, I did find the time to open it and get access the ICE System1 board.

As mistakenly mentioned in my original post, the component that was faulty isn't D200 but right next to it (missing now).

I still can't identify this smd component that shorted and burned, there's no numbering for it, though my guess is it's another capacitor like the beige ones between D200 and T204 in the picture.

These little smd caps tend to randomly short from time to time.

The BL5 turns on and a buzzing sound is coming out when I switch to an audio source (CD/AUX/RADIO), and I can also hear the remote control signal when I press any button.

So it seems that now missing smd component plays a part in that buzzing problem. The BL5 was working perfectly fine up until that component blew up.

I don't think anything else has been damaged. I also inspected and checked everything in the primary and secondary.

I'll check output power rails and see if there's anything abnormal and keep you in touch.

Jay.

 

Beobuddy
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Beobuddy replied on Wed, Nov 11 2020 12:37 PM

There are 4 identical ceramic capacitors around the bridge. Mostly they are 10nF and take ones which can handle 1kV. Then you're safe.

If you want to be sure, desolder one and measure it.

I find it hard to believe that this causes your transistion noise.

JayBL5
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JayBL5 replied on Wed, Nov 11 2020 1:08 PM

@Beobuddy

After several hours spent searching and probing with my oscilloscope, I figured out what was causing the buzzing...

A tiny 0 ohm link has burned between the two PowerLink connectors on the input board.

It connects the pin 7 of both PowerLink connectors to the Audio ground.

I also replaced it as well as the PowerLink cable. It might be the cause and was shorting wires when twisted, but I didn't want to try haha.

It stiff doesn't explain why a tiny capacitor on the primary side of the SMPS blew up. Might just be an unfortunate coincidence, I presume.

Anyway, so far everything is fine now, got my pair up and playing and saved >$2000 Smile

In case someone has the same issue (buzzing sound and the BL5 turns off/on randomly). Unplug it from the PowerLink and digital cables, then start a calibration. If the calibration is successful without buzzing noises that means there's something wrong with the Input board.

 

TWG
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TWG replied on Wed, Nov 11 2020 3:09 PM

Thank you for your valuable work.

Dennis
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Dennis replied on Wed, Nov 11 2020 5:09 PM

Well done! Thank you for returning with the solution. Smile

I'm glad to hear that you didn't have to have another chassis replaced. Hope at least some of the 5 replacements were covered by warranty? Quite disappointing that a pair of speakers in that price range fail that often and having to pay a fortune to have them repaired.  

Good there are some passionated people keeping them alive! Yes - thumbs up

/Dennis

JayBL5
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JayBL5 replied on Wed, Nov 11 2020 10:02 PM

> I'm glad to hear that you didn't have to have another chassis replaced. Hope at least some of the 5 replacements were covered by warranty?

Only two of them were covered, but for the others they gave me some discount. It was about $500 to $700 per chassis replacement, on average.

But the last price they gave me last week was outrageous (over $2000). I'm glad I refused and fixed it myself. It ended up costing me half a day of my time and about $1 for both parts!

From now on I will fix my BL5 myself when they will fail, at least as long as I can find replacement parts and components.

> Quite disappointing that a pair of speakers in that price range fail that often and having to pay a fortune to have them repaired.  

Absolutely! I love my BL5 (incredible rich sound) as much as I hate them for being so prone to random failure without even using them daily. And when I do, I never go over 50% (volume at 48). The speaker's membranes are still in perfect condition, even after over a decade.

On the other hand, the BeoSound 9000 driving them is flawless. :)

Jay

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