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
This is the first time I've opened a BL9, and I'm very impressed. A customer in Tel Aviv imported a pair of these from Poland, and they had a number of problems. Orange and Red LED's when not supposed to, Poor quality sound, and one of them has a crackling sound - it's NOT the tweeter!.
I have already done my standard procedure - replacing all the SMD electrolytics on the Crossover PCB's, and those faulty electrolytics on the ICE PSU. All solder joints resoldered on ALL PCB's - there were many cracked joints. Discussed in expanded detail later.
Both BL9's reassembled, and all problems are solved, except for ONE - the intermittent crackling sound on one BL9. The other one is fine.
I've read through all the previous BL9 posts which may have indicated a cause for the crackling, but no luck. I did find many posts with BL9 PSU failures, which were solved here, and those members may be able to obtain some help by reading this post carefully.
I am very fortunate that I have another perfectly functional BL9 to use a a swapping source. So, I am now at the stage of swapping individual PCB's between the BL9 chassis, in order to isolate the faulty PCB. I will then troubleshoot that PCB. Sending the BL9 to a "Service Center" is not an option - the problem will be solved here.
Here's my large table open and occupied for organized swapping of the PCB's.
So, I will discuss now my work already done on this ICE PSU PCB.
I saw that other members found a blown fuse, and hoped that a replacement will solve the problem. Wrong.
Firstly, it must be understood that this PSU is a Switch-Mode (SMPS) PSU.
It is NOT a Linear PSU, like the Pre-2000's models sold by B&O.
A SMPS operates at very high frequencies, and reserve voltages are well over 300Volts.
That means that the high frequencies cause very high breakdown rates on the passive components (such as resistors and capacitors), and also the Semiconductors can overheat, if the heat by-product is not managed correctly.
Secondly, when a fuse blows in a SMPS, that means that (beyond all doubt) there is a real and catastrophic problem, usually in the Primary (High-voltage) section of the PSU.
Throwing more fuses at the PSU is guaranteed to cause only MORE incremental damage.
Before I started work on the PSU PCB, I did a visual inspection to identify any visual clues for defects.
There were no bulged capacitors (but no-bulge is NO guarantee that a capacitor is functional or not), and I was impressed to observe B&O's choice in the components - Panasonic, Vishay, and ChemiCon - all very high quality.
The only component of which I didn't approve, was the RIFA paper "X2" 220nF supppression capacitor C111 275VAC, especially since the other "X2" cap C113 is a super-high-quality Vishay 339 rated at 310VAC.
In Europe, 310VAC rating is more "forgiving" than a 275VAC rating. Why would B&O have chosen to use the Rifa in one X2 position, instead of installing 2 identical Vishay caps? Maybe lots of Rifa caps in stock?
These Rifa X2 caps are notorious for exploding and causing all types of damage. After repairing hundreds of Tektronix oscilloscope PSU's, ALL with Rifa X2 explosive damage, I automatically junk these Rifa paper caps whenever I see them installed. They have not stood the test of time.
So, replacing the Rifa paper cap (with the identical Vishay 339 as C113) would be my first recommendation, when looking at a blown fuse. And of course, check for any other collateral damage.
The other visual damage was the cold-solder (cracked) joints on the PCB underside.
Very common on SMPS PSU's, especially with today's unreliable Lead-free solder.
So, I resoldered all the solder joints with Kester 63/37 fully-leaded solder.
I now started measuring all suspect passive components.
The first suspect was R114, a Carbon Composition 1/2W resistor. Carbon Comp resistors do not age well - they absorb humidity, and depart from their specified resistances, sometimes drastically.
This 470R measured over 600 ohms. Predictable, and I replaced it with an new Carbon Comp resistor.
Carbon Comp resistors are installed for a very good reason - they handle high-frequency pulses better than any other resistor types, and it would be foolish to replace it with any other type.
The next suspects were the electrolytic capacitors.
Normally in SMPS's, the small capacitors fail at a much higher rate than the large units.
So it was here.
The large Vishay, Panasonic FC and Chemicon electrolytics checked perfectly OK on my ESR meter, and there was no need to replace them. Excellent quality, and super-reliable.
Only these electrolytics needed replacing (circled in red):
22uF/50V C514 and C516
100uF/25V C425, C429 and C611.
I used my gold-standard for SMPS's - Nichicon UPW and UHE.
Subsequent testing proved the SMPS completely functional.
Following this with great interest, as it is nice seeing someone repair some of the newer B&O products - especially as I guess you don't have any schematics to help you? I'm sure this thread will become useful for others in the near future.
Keep up the good work.
/Dennis
Thanks for posting! I own a pair of Beolab 9's myself and definitely appreciate seeing some of the issues I may expect down the road.
Before you start to replace all the capacitors, start with identifying the crackling sound. Where does it come from. Just from one driver, or does al the drivers contain that intermittent crackling sound? Crackling noises are never caused by degraded electrolytic capacitors.From all the defective BL9's I've had, none of them had issues caused by these.
Beobuddy:Crackling noises are never caused by degraded electrolytic capacitors. From all the defective BL9's I've had, none of them had issues caused by these.
From all the defective BL9's I've had, none of them had issues caused by these.
All the electrolytic capacitors have already been replaced.
That's the first order of work - to replace ALL confirmed defective parts.
The crackling is the ONLY problem remaining, therefore you are correct that the capacitors are NOT the cause of the crackling.
The crackling comes from the tweeter.
The tweeters were already swapped in order to determine whether the problem was from the actual tweeter. Not so.
So the first PCB to swap will be the X-over.
My instinct is pushing me in the direction of a cracked SMD solder joint somewhere, but time and further checking will determine whether I am correct.
Have you actually solved any crackling problems on the BL9's?
I’ve solved crackling noises on BL4, 4000(both mk1 and 2), BL1, 3, 5, 7 and 9.
Causes are diverse.
Menahem Yachad: That's the first order of work - to replace ALL confirmed defective parts.
You do not know this, unless you desolder all capacitors for a reliable measurement. Even then a measured valid value isn’t a guarantee that it works as it should.
Beobuddy:You do not know this
On the contrary!
Checking ESR in-circuit is a perfectly reliable method of determining whether the capacitor is functional or not (except in a tank circuit).
For capacitance, you are correct. Capacitance MUST be checked out-of-circuit.
However, after ESR has confirmed a bad cap, the capacitance is of academic value only.
Can you expand on the actual causes of crackling problems in your past experience with BL9's?
PCB1, also described as the Crossover PCB, is the faulty PCB.
Next step is to isolate the faulty components.
Checked the Inputs and outputs of the STK amp.
Pin 11 on the STK403-130 is the input - shows the crackling, so I'll be reverse engineering the circuit backwards from the preamp to the STK to find the culprit.
The schematics would be helpful here....
Scoped all the inputs and outputs of the MC33078 Dual and MC33079 Quad OpAmps.
Without a scope, this troubleshooting would be absolutely impossible.
What I was looking for is exactly this: OpAmp input Clean, OpAmp output Distorted.
Found this exactly on IC204 MC33079 - Pins 12 and 13 Input - Clean, Pin 14 Output - Distorted.
This is now the area of interest, as shown on the photo. This IC is under the metal shield on PCB1 (Crossover).
Either the OpAmp itself is defective, or the surrounding components of Pin 14 are defective, and are introducing distortion onto that rail.
Currently diagnosing.
Most likely that it wil be caused by the 33079. With some coldspray you probably can influence the amount of distortion.
Yes, I would very much like to believe that it is so simple - just replace the 33079.
Experience has taught me otherwise.
So, I had already used Freeze Spray, and that caused no change at all.
In the old days (before SMD), it would have been very simple - just desolder the legs of the parts around here, and in 20 minutes, the defective part is identified.
But here, I've had to cut the PCB traces from Pin 14, which go to the surrounding parts, and I have not been able to cut every trace, simply because they are so small, that there is the real danger of not being able to repair them afterwards.
So if you look at the above picture, to the left of the red circle are 8x MMBF4393 FET's.
The Drain pin on the right-side set of 4 FET's is connected directly to Pin 14, therefore also shows the distortion. I have no means of cutting that connection, so my next step is to do DC voltage checks on all those pins, to see if there is one pin, slightly non-uniform.
A real journey with these micro-parts, and being unable to desolder and lift legs.
I sent a very specific and technically detailed email to B&O, and requested the values of some SMD capacitors in the area of the questionable 33079's.
The reply was basically - "Go to a Service Center and pay somebody with much less experience and ability, to replace the Entire PCB 999"
Needless to say, I was not impressed.
That's the best way to build a massive base of one-time customers, who never buy again - just like what Bose did.
Anyway, I removed a bunch of SMD capacitors for testing, and was unable to find any defects.
So I ordered a bunch of 33079' Quad opamps, and replaced IC203 and IC204.
See below - the suspect IC's removed.
And the new IC's installed.
I also reflowed the solder on the other SMD chips, just for safety's sake.
I'll be reassembling the BL9's in a few days, and then testing.
After 48 hours of testing, the crackling is gone.
A quick summary of the solution:
Replacement of some capacitors and one carbon resistor on the PSU PCB, as shown above
Replacement of all SMD Electrolytics on all 3 PCB's in the PCB999 module.
Replacement of 2 MC33079 Quad OpAmps on PCB1 - the Crossover PCB (inside PCB999 module).
Done successfully, in spite of me having to do extra troubleshooting work, because B&O refused to share requested info.
Fellow BL9 owners having overheating or startup problems would do well to copy my solutions on the PSU PCB, as a starter.
It has taken a serious amount of time and perseverernce, but you're there. Congrats, well done!
You can arque about the response from B&O but they don't offer diagrams from all the products since 200x or so.However they offer a replacement chassis (referred by you as PCB999) they repaired and checked themselves.
It's probably the most reliable solution and above all the quickest solution for the customer, they think.
Beobuddy: It's probably the most reliable solution
It's probably the most reliable solution
I'll warrant that my repair is more reliable than an original (even if new) exchange module.
Those original SMD capacitors are incredibly unreliable, and after having been replaced by regular High-quality leaded units, this unit will outlast an original B&O exchange module.
Not to mention that I reflowed all the SMD joints with LEADED solder - that alone will add years to its life, when compared to the junk unleaded solder used originally.
Menahem Yachad: I'll warrant that my repair is more reliable than an original (even if new) exchange module.
To claim that a board reworked by you is more reliable than one refurbished by the original manufacturer - or even a new original.That is some statement.
You found the problem and you repaired the product. That's fine.
You are entitled to your opinion, and you and I have not always agreed.
Menahem Yachad: Not to mention that I reflowed all the SMD joints with LEADED solder - that alone will add years to its life, when compared to the junk unleaded solder used originally.
If we talk about stability, I don't agree to mixing leaded and unleaded solder types.They have different eutectic properties.The risk of fatigue and cracking is high.I certainly wouldn't do it in a product like a speaker, considering the vibrations in there for hours every day.Did you see many problems with the unleaded solder used in B&Os products (or elsewhere)? And which problems?
Menahem Yachad: ... and after having been replaced by regular High-quality leaded units, this unit will outlast an original B&O exchange module.
... and after having been replaced by regular High-quality leaded units, this unit will outlast an original B&O exchange module.
Some of the same issues apply to fitting components with leads in place of SMDs.Not in vibrating environment like this, unless some form of physical relief can be introduced and all old solder can be removed and replaced by a good solder containing a little silver to prevent fatigue.
Menahem Yachad: Those original SMD capacitors are incredibly unreliable, and after having been replaced by regular High-quality leaded units, this unit will outlast an original B&O exchange module.
I never had more problems with SMD capacitors that I had with ones with leads.Did you have many problems with the original SMD capacitors?May I ask what problems and in which products?
I understand, that the problem actually wasn't capacitor-related here.
Edit:
In my first post for this reply I asked if there was any chance you could show us your workspace and tools?With all the talk about reliability I was particularly interested in knowing which ESD-precautions you have taken.
Now, looking again, I found your photo in the first post (and subsequent),...
Please tell me that is NOT a plastic table???
With circuit boards lying directly on top of it???With plastic parts, plastic cups and plastic tools all around?
What's that on the floor? A carpet? In an electronic repairshop?
And your other table - is that laminate?
I spot no ESD-precautions whatsoever!
Quite contrary in fact.
Martin
Martin,
You're right - it is some statement, and I'll stand by it.
My workshop organization, cleanliness, environment, workmanship, ability and attention to detail is far above any norm, and the results show.
It would also exceed any critical industrial standards, even though I have no need or intention of applying for certification.
After working in the Israeli electronic industry, arguably among the most advanced in the world (based on the equipment we are proud to produce and export world-wide), I learnt what a proper electronics workshop should be, and I duplicated it in my own workshop.
Based on what I've seen on YouTube technician videos, I also realize that not many technicians have the privilege of creating an ideal workshop like mine.
It may be difficult for you to accept, but I really don't need anyone's approval, other than that of my customers worldwide.
I'll address your related concerns further down
It's common knowledge that B&O had quality issues in the past, and they've done a great job at attempting to solve them, evidenced at least by the good quality of some of the components in these PCB's.
However, every one of the SMD caps on the Black ICEPower PCB was far off-spec, measuring the ESR and capacitance out-of-circuit after removal.
I expected that, and the replacement of those caps, solved the Orange light overheating problem.
So, at least on this machine, that is evidence of failure-prone SMD caps.
It's a well known problem that during the SMD PCB manufacturing cycles of Preheat and Flow, the Electrolytic caps take a beating at those temperatures.
SMD caps are subjected to destructive heat cycles which Leaded caps were never subjected to.
And current Electrolytic chemical technology does not yet have a solution for that.
So, it stands to reason that any SMD cap, no matter the make, starts off its life partially crippled.
For at least 40 years, my solder of choice is Kester 245. I have 2 versions - one 63/37 and 62/36/2.
They meet all the requirements for my varied applications.
If we're talking about vibrations, my goodness, then what is Unleaded solder doing on these PCB's?
Unleaded solder barely manages to keep from cracking under even the best conditions.
If vibration is a valid argument, then that should be a good enough reason to forbid the use of Unleaded solder on these PCB's.
Since you ask about problems with SMD capacitors, let me throw a four-letter word in here. B-se.
I have repaired literally HUNDREDS of B-se Wave PCB's, ALL with failed SMD capacitors.
It is an absolute reliability disaster, and an insult to the customers for the prices they ask.
There are probably other manufacturers just as bad, but I can speak only from my personal experience.
The BL9's were opened on our spare table - plastic, simply to spread out the parts, which were then taken into my workshop, as required.
At that stage, I was certainly not concerned about ESD.
That photo is NOT in my workshop.
We do NOT own any carpets - not sure where you got that from. Carpets are not common in Israeli homes.
I don't see any need to post any photos of my workshop, apart from that on my CondorAudio website.
My goal is solely to share the process, so that other BeoWorlders may benefit.
There really isn't yet a lot of technical help with these newer SMD products. And given B&O's refusal to assist those BeoWorlders who DO have the technical ability to do the work, so I have chosen to take a small step in making a difference, to step in where B&O has left the playing field empty, and help point the way for other BeoWorlders to solve their issues, to the highest standards.
Suffice to say -
My workshop is hermetically airtight - it's actually our bomb-shelter room.
It has an activated air-cleaner and a humidifier.
My Hot-Air Soldering equipment is ESD safe - that's the equipment I use for SMD.
I have grounded ESD wrist-straps
When necessary, I lay a large rubber mat on the table.
Just because you don't see my equipment, doesn't mean that it isn't there.
You are welcome to visit and spend some time with me inside my workshop - you'd probably be jealous , and then we'll have a couple of good Israeli beer, outside of my workshop!
Any other concerns which you feel may stand in my way of executing work to the highest industrial standards?
Duplicate Post
The final culprits were the 2 ICs that was replaced?
Orange light (solved first):
Crackling (solved last):
This does NOT imply that replacing IC203 and IC204 in all defective BL9's will solve the problem, but it does point to a possibility that any or some MC33079 OpAmps may develop faults. So ALL MC33079's on PCB1 should be checked with a scope, in order to determine whether defective.
Will the ic be the cause of the orange light and not the caps?
Teyelvis: Will the ic be the cause of the orange light and not the caps?
Absolutely Not!
Those IC's are in the Audio Circuit only.
Also proof is that immediately AFTER the capacitor replacement, the Orange light problem disappeared.
At that point, I had not yet started any troubleshooting on the IC's, and the crackling was still present.
Therefore I can conclude beyond doubt, that the Orange light problem was related to the capacitors, and the Crackling was related to the IC's.
I hope that makes it clear ;-)