Beolab 5 upper bass on-off issue

[marexy]

Hi

Hope anyone can help. Beolab 5  .SW 2.6 Seeial 21… has

bproblem that upper bass is going on and off ..at start all is ok after 10 min of playing it is starting to go on ad off.

Aany idea what can be wrong?

TThanks

[NQVHNWI]

Are you seeing a flashing red LED?

 

[marexy]

No Led is green all the time. Totaly normal.

[NQVHNWI]

so you play music…..

what sort? light orchestral or big heavy boom bass? for 10 minutes?

no LED indication, then the whole speaker cuts out to standby (firm red LED)?

or just goes fully dead with no LED change?

or it continues to play the upper mid, lower treble and upper treble drivers? – just the 15inch sub goes down?

[marexy]

Led  stay green as normal in play mode. It paly’s normal just upper mid- bas after some time cuts on and off. Like bad solder joit or bad connestion but i allready check that.  Maybe it is a litle sooner if i play loud yes.

[NQVHNWI]

I have known one of my BL5 to trip-out totally (red LED flashing) when playing very loud, very heavy bass.  It is Loudspeaker thermal protection. Fortunately, I did not have the problem if I didnt try to overload it and play normally. This is what the manual says….

The loudspeaker is equipped with a thermal
protection system which prevents the units
from overheating. Should an error occur, the
system automatically switches the loudspeaker
to standby – and the indicator light
flashes red.
To restore the situation:
> Disconnect the loudspeaker from the mains.
> Allow the system time to reset (approx. 3–5
minutes).
> Reconnect the loudspeaker to the mains again.

Should the problem persist, contact your Bang &
Olufsen retailer.

Regardless, it sounds like you have an internal fault and should get it checked out by an approved B&O service engineer.

 

 

 

[marexy]

I repair  some B&O electronic.  But till now i had non of Beolab 5  to repair and that kind of error may be standard fault here ant there.  That are my personal speakers. Just hope for an answer from someone who has repaired that kind of error as here are some guys with a lot of knowledge on repaires 🙂

[NQVHNWI]

marexy wrote:

I repair some B&O electronic……..Just hope for an answer from someone who has repaired that kind of error as here are some guys with a lot of knowledge on repaires

Clearly, you have more knowledge than most if you are prepared to go inside a BL5 and make repairs.  I don’t think any advice I can give you – or 99.9% of the other Beoworld members would be useful?  I wish you good luck in solving the problem.

 

 

[marexy]

Thanks, will try. Some time agoo had been more on forum as now have less and less time. Hope Lee or any other legend can geve some hint ??.

[BeosoundLondon]

Hi,

I thought I’d post here given somewhat related. I’ve recently acquired a pair of BL5- does sound great to my ears. I’ve just noticed not much sound seems to come from the dome upper bass driver (the one below the larger acoustic lense) – the dome seems to vibrate a little but I can’t hear much if I put my ear close it it – unlike the tweeter and the 2 other bass drivers. Same thing on both speakers.

i was curious if anyone else had the same experience ?

 

[NQVHNWI]

Yes, I have.

I have found the upper tweeter wears out. You can test by carefully muffling off the lower Tweeter with a soft pillow or cushion and play a high frequency sinewave track through 1 channel. This will identify if you are getting equal sound from each.

I found that one upper tweeter had gone – and as a matter of caution (the Tweeters cost relatively little), have the Service engineer replace both. This ensures equal sound and not having to do it again at £200/hr!

[Beobuddy]

I’ve done dozens off these and the BL5’s are becoming a bit risky, to say the least.

@ Marexy. Change both 2 modules at the side of the chassis with each other. If the problem travels from the upper bass to the lower bass, then you know that it is an amplifier problem.

If the problem stays at the same driver, then the problem might be the mute section or lies in the filter section.

Btw,  tweeters are very costly nowadays.

[luice]

marexy wrote:

Hi Hope anyone can help. Beolab 5 .SW 2.6 Seeial 21… has bproblem that upper bass is going on and off ..at start all is ok after 10 min of playing it is starting to go on ad off. Aany idea what can be wrong? TThanks

Similar issue here, after turn it off when I turn it on yesterday I get same issue.

[BeosoundLondon]

Thanks a lot for this. I think my upper tweeters work great. I just noticed the upper bass / mid range driven (the one exposed at the level of the larger acoustic lense on the large aluminium disk) doesn’t tend to produce much sound even if I put my ear fairly close to it. Much of the speakers sound seems to be coming from the 2 bass drivers and the tweeter.

[marexy]

Double post…

 

[marexy]

Hi Beobuddy

Done that..and yes as you guess, it is amp modue fault.

So i am looking for IcePower 1000A Mk2 module.

Or shematics for repair, as Icepower company DK does not  share shematics sadly.

It is interesting that BL5 share some vital parts with BL7.4 and BL1

 

[Beobuddy]

There are no (public) available diagrams. That makes them hard to repair. If something goes wrong during trying then it can go severe wrong due to the strong power supply driving them.

The modules aren’t manufactured and sold anymore. I don’t expect that they will make another batch off modules due to the limited specifications off these and it probably only will be to replace defective ones.

I’ve managed to fix a number of modules and am working on reverse-engineering back to drawing diagrams for future repairs. I’ve invested in a sincere amount of a money in special power supplies, differential probes, electronic loads, parts, etc. to get them fixed. But, agreed,  with original diagrams life would be much easier.

If you’re searching for a quick fix, then I would suggest that you look for a cheap BL2 and take out the module in that one.

At first glance there seems to be some resemblance but there are difference (BL7-4). I don’t see that with the BL1, other that it has also an ICE powered section for the bass. Mid and high are driven by Class-B amplifiers.

[marexy]

Hi

Thanks

As i am in electronic rapair / not as much as you / but i hope i can repair.

Tweeter have almost same amp as in Beolab 7.4 .

Bass modueles BL5 are 2x IcePower 1000A MK2.

Bass module in BL2 is 500w type.

Tweeters are from ScanSpeak as far as i find out.

upper bass is the same as BL1..if not mistaking.

I have now ordered new IcePower 1000A MK1 And will check if will be ok.

BBiggest issue at BL5 i see on SW -PCB.

Here i can not see any option but only original.

 

[Beobuddy]

Ad I already mentioned. BL2 and BL5 have the same modules. The 500W modules differ in connection sockets

The lower and upper bass from the BL5 are the same. Both Class D as the bass from the BL1. Design wise different boards and components.

If you’re able to order a new ICE 1000W module, not the stil available 500W, then you probably luckily solved this issue. As changing the modules for the bass made difference.

[marexy]

Beobuddy wrote:

Ad I already mentioned. BL2 and BL5 have the same modules. The 500W modules differ in connection sockets The lower and upper bass from the BL5 are the same. Both Class D as the bass from the BL1. Design wise different boards and components. If you’re able to order a new ICE 1000W module, not the stil available 500W, then you probably luckily solved this issue. As changing the modules for the bass made difference.

Correct..my mistatke ..BL2 and BL5 have same amp board. Will try new board..hope it helps. But would still like to repair bad one. I change some IC  change some caps , but still same issue. When starting work ok for 5 min. and after that start to cut off and on ..off and on and there is no patern for how long ..strange

[Author]

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