I have found moisture inside there on my 2006. It appears to come in around the tail light assembly. A direct spray when washing, or a driving rain seems to be able to get inside there. Luckily I didn't kill my H/K amp, but I did have a Blitzsafe interface fail due to moisture corrosion.

 

Hi Itphoto,

Yes, there is no question regarding this being the result of moisture accumulation in my amp. It doesn't take much moisture plus a little contamination from body salts (fingers) and any debris let over during the manufacturing cycle to produce an ionized path for small currents to flow. Once you get current flowing between two adjacent solder joints, the tin in the solder will immediately become mobile and start to form shorting paths. It's the bane of printed circuit board manufacturers and one of the reasons why industry conformally coats many of their boards. An uncoated board doesn't stand much of a chance of living long in an environment where condensation can take place, or worse yet...actual moisture intrusion as you point out from around the rear light. Well, if there is anything good that has come out of this effort, it would be that I've learned a lot (and still learning) about the KBus (or sometimes called the IBus) that BMW built into our Minis. As a means of taking my troubleshooting process to the next level, I've had to build up an interface that will allow me to tap into the KBus and connect it up to my RS232 port on my old laptop. I found a free application online that will parse out the communication packets that go back and forth between the head unit and the HK Amp. So as soon as I get the interface hooked up and working with the downloaded App, I'll be starting the next level of isolatinig this failure. It sure would be nice if I found a hidden short somewhere as they can usually be removed with a good cleaning. A defective LSI chip on the other hand presents a real issue as I'm starting to get the impression that I'm not going to be able to get replacement parts for this Amp...anyway...I'm working on the interface board right now so have to get moving on that phase of the project...Thanks for your input re: water around the tail light.

Ed

 

Good luck tracking this down. I, along with many others, I'm sure, am hoping you are successful since I assume that someday my amp will fail too.

 

Update: Last night I realized that the right angle I/O connector assembly that is attached to the main amplifier board is actually a "push on" sub assembly. I popped the I/O assy off and was able to get a much better view of the corrosion and contamination that I've been seeing all along. The damage done by the corrosion was far worse than I orignally thought. Several of the plated through holes that the power leads go through are partially "etched" away...a result of the electrolysis that was going on under the connector when voltage was applied during those periods of time when moisture was present. In some respects this is a "good" finding as I just received a email response back from Harman/Kardon and they informed me that any support I might have been expecting would have to come from my original Mini dealer...and I'm sure that my dealer doesn't have a room full of replacement parts for all the electronic equipment in their Minis. Their response will most likely be..."Buy a new H/K amp and we'll call you when it comes in....!". So if in the final analysis this corrosion turns out to be the root cause of the problem, it should all be repairable by a technician skilled in working with microelectronics. I am photo documenting all of my disassembly actions and all of the Mini owners who have had a similar problem will be able to see exactly what it will take to get into the amp and repair the issue...assuming of course that their issues are identical to mine. Today I am removing (unsoldering) the main power connector as the major part of the board damage is in this area and unfortunately I can't see the full extent of the damage that exists directly underneath of the power connector at the board interface...all will be known in a couple of hours.

At this point there is some obvious points that are coming to the surface:

1. Harman/Kardon has a well made amplifier and they have used assembly techniques that are considered normal in the printed circuit industry for a commercially manufactured piece of electronic equipment. They have even taken the time to apply conformal coating to the entire board in an attempt to make it somewhat impervious to small moisture condensation issues. Knowing that their amplifier is being used in an automobile where vibration could be an additional failure mechanism, they have staked most of the components in an effort to eliminate vibration induced fatigue of the component attachment mechanisms.

2. The H/K amplifier is NOT a hermetically sealed unit and BMW (Mini) HAD to know this. This amplifier should never been placed in a location where there was any possibility of moisture intrusion. The amount of damage that I have documented in my H/K amp is consistent with a build up of moisture that exceeds normal condensation from temperature extremes. Additionally the damage so far is extremely localized around the power input connector and the immediate surrounding area and is not broad spread across the entire board as would be the case with condensation.

3. At present I have NOT isolated the root cause of my original failure and as such I can not point to the present observations and say this is what caused my failure, but I can say that what I have found should not have happened. Moisture and electronic equipment are totally incompatible.

Ed

 

Hi Ed,
Any updates or pics? In your experience so far, would you recommend preventive action for folks who have a working unit and want it to stay that way? (drip shield, coatings, etc.) I am comfortable with the details.
Your deep dive into this is interesting to follow. Many thanks.

 

Hi papa-j,
Well, as one might expect there are many new updates. The most discouraging of these updates is the total lack of support available from both Harman Kardon and my Mini dealer. Harman Kardon totally rejected my request for documentation on their amplifier and told me my only source of assistance should come from my dealer. Reluctantly I called my dealer and requested documentation on the HK amplifier and got the expected response..."we don't have any additional documentation on your HK amplifier other than what was supplied with your MC when you bought it". Additionally they have no means available to obtain this documentation nor do they know where I could go to obtain documentation (mainly a schematic). I wrote back to Harman Kardon again late last night, but I'm not expecting anything of any value to come of that email.
As for my troubleshooting effort, I have cleaned up all of the contamination and tested for shorts and opens and all appears to be OK in that regard. Unfortunately, my original failure still exists. To that end I have built up an interface circuit that permits me to monitor the KBus control signals that go between the Head Unit and the HK Amplifier. When the Head Unit is turned on it sends a broadcast message out on the KBus indicating that it has been turned on. This message appears and is in the proper form. The amplifier at this point is supposed to send back a KBus message indicating that it is also "awake and ready for communications". This message from the amplifier is never generated, so all communications between the Head Unit and the amplifier stop at this point. I have been into the amplifier and done considerable probing in an attempt to obtain some useful data that just might shed some light on why the amplifier is completely dead. This process most unfortunately is being done completely in the dark without a schematic to assist with understanding the measurements. If there is any "good news" associated with my findings at this point, it would be that the amplifier appears to be completely dead which may indicate that there is a single point failure somewhere on the board that is keeping the amplifier from turning on. Adding to the complexity of this troubleshooting process is the fact that the amplifier is assembled using Surface Mount Devices which are extremely small and do not have the "normal" type of designations on the body of the components as there just isn't enough space to put the normal amount of textural info. Therefore I am left without any means of knowing whether I'm probing a SMD package that contains a FET or a bipolar transistor. The voltage reading I am getting on the pins of several devices are inconsistent with the normal bias conditions for either a FET or a bipolar transistor which again tends to support a complete shutdown of the amplifier. The troubleshooting effort continues even without the use of a schematic.
Regarding your question of preventative methods, I can tell you that if and when I am able to get the amplifier back into working condition, I intend to go out and purchase a tube or two of industrial RTV and completely seal the amplifier enclosure to stop the intrusion of any moisture which could make it's way to the amplifier board. The product that we use here at work is RTV 162 manufactured by "Momentive performance materials". If needed, I can obtain the name of our vendor for this product (send me a PM). I have loads of images that document all of my findings up to the present time and I intend to make them all available, but right now my efforts are being directed towards getting this failure tracked down and getting the amplifier back into working condition.

Having said the above, all who are following this effort should be aware that if the failure is isolated to be one of the several LSI devices on the board, there may be no realistic means of repairing that condition as I am sure there is no source available for obtaining these devices (I can't even get anyone to provide me with a schematic let alone replacement parts). On the other hand my hope is that the failure will be isolated to a open/short or defective discrete component that CAN be replaced or repaired.
More updates as they become available...

Ed

 

Keep up the good work. Your description seems consistent with the 'trigger circuit' suggestion; see post # 16 above.

 

My fault isolation effort continues on the HK Amp. My findings at present are the following:
1/ The moisture intrusion into my amp was not the root cause of my failure.
2/ I am forced into reverse engineering the schematic for the amp. There are limitations on just how far this effort can go. Coming up with a schematic for most of the circuitry associated with the discrete components, although difficult, is workable and effort continues along this line. At the present time most of the LSI chips can only be shown as a box with pin numbers that have no identification.
3/ I have partial schematics for the input components associated with the "Radio On", "Exhaust Temperature Sensor" (whatever that is used for) and the "Telephone Mute". These lines are definitely required inputs for the amplifier to function properly.
4/ I have the amplifier set up for troubleshooting out of the car using a .5 Amp 12vdc wall wart. This has allowed me to troubleshoot the input control lines described in #3 above. These inputs require 12VDC input in order for the amp to "turn on". Which it appears to be doing contrary to a previous statement I made about the amplifier being "completely dead".
5/ The amp creates internal voltages of +3.3VDC for some of the low voltage IC's and also creates a -10VDC for some quad Op Amps that are used on the board.
6/ I have been able to trace my KBus input signal up to an IC that is identified as "ELMOS 10020B". This device receives the 0 to 12VDC logic levels coming in on the KBus and has a logic output of 0 to 5VDC that goes over to one of the LSI chips. I have been unable to find any return KBus signal back from the LSI device to the "ELMOS 10020B" IC. THIS IS NOT A GOOD OBSERVATION! Additionally, I have not been able to obtain a data sheet for the 14 pin SMD "ELMOS 10020B" IC so I really don't know what pin(s) I should be looking for a In/Out KBus signal on. If anyone has any sources of a data sheet for this device it would be of great assistance. This lack of a return KBus signal appears to be the failure of my HK amp and the cause of this missing signal is where I am placing my emphasis.
7/ My previous statement regarding the voltage measurements around the discrete transistors "not looking right" was the result of me not have the "Exhaust Temperature Sensor" input line tied to +12VDC when I started my original troubleshooting. This condition went away when I realized this input was required.
More updates as new data becomes available
Ed

 

Update:
Did a search today on the 10020B and found an obscure listing in a German forum regarding the ELMOS 10020B and next to this entry was "E910.05 (www.elmos.de)". I went out to the elmos URL and looked up the E910.05 and it appears to be our 10020B unit. I can now move forward with the troubleshooting effort of the KBus (or backwards as the case may be...)

Ed

 

Have you found any markings or numbers for the amp on the case or pwb? I can do some parallel search for info. You are doing nice play-by-play. I appreciate the detail.

 

I am following this as my amp is making cracking sounds. It started with one speaker and propagated to all speakers. I expect it to die soon. Did your amp started this way? I took mine apart and looked it under microscope hoping to find a bad solder joint, thinking of a bad contact since the noise comes and go. But, everything looked good. I have no corrosion as you did or at least did not see any. Also, observed the capacitors (the electrolytic ones) looking for signs of damage. No luck. I thought about the output FET ICs but they might be hard to find and even if found the forming of the leads will not be an easy task. Looks like you have the facilities to troubleshoot it. Keep posting.

Juan

 

Hi Papa,
Yes, if you click on the "Gallery" link in any of my posts it will take you to some pictures that I originally took when I first removed the amp from my car and started the disassembly process. I have dozens more images, however I haven't had the time to process them and get them up on the site. You will find a couple there that have the sticker with all the info for the amp visible. I wish you all the luck in the world with your effort and hope you have better results than I did.
A few points of interest for you Juan:
1. With regard to my failure indications. I woke up one morning and turned my radio on and NOTHING happened...just no sound at all.
2. The corrosion and associated contamination was only partially observable using a microscope and even then you had to look carefully in the area between the adaptor board and the white interface connector that has 6 pins. 3 of these pins carry the ground path and 3 carry the +12VDC path. I had one of the technicians in our shop unsolder this connector and you will be amazed when I post the images of what I found on the backside of this interface connector.
3. I have identified the output devices, so if anyone ever isolates them as a possible failure source, they should be relatively easy to replace by someone trained in the use of a small soldering iron and the multipin removal process. The device is manufactured by STMicroelectronics (TDA7454). You can view their datasheet at http://www.st.com/stonline/products/...re/ds/1775.pdf I'm pretty sure the leads come already preformed for insertion directly into the board so you shouldn't have any issues there should you ever have to replace one.

As for my most recent activities, I've been putting in a fair amount of effort into reverse engineering the amplifier circuit and recreating the schematic. Yesterday I used an oscilloscope to monitor all the signals around the ELMOS E910.05 KBus transceiver. From everything that I see it appears that this device is functioning properly as all pin voltages and signals appear normal, however there is no return signal being sent back to this IC. I traced the path for this return signal and it comes directly from what I believe is one of two CPUs on the board. This is a very bad finding as it means either this CPU is dead or devices providing control input to the CPU are malfunctioning. I have several areas that still require probing so we're not dead in the water yet. There is an assoicated RAM chip (a CYPRESS 32Kx8 3.3V RAM - CY7C1399-15V1) and what I believe may be an EPROM (the square LSI devices with the circular white labels in the center). These devices would have to be addressed by the CPU in order to process the incoming KBus commands, so they are my next area of circuit analysis. If the RAM was malfunctioning we could replace it, however if the EPROM is dead, we have a major issue as HK has all but refused to support me in any way at all. Along these lines there has to be a Clock signal for the CPU to function properly and there is a crystal on the board (NDK Crystal - 16.934MHz) that could be providing this function, so that has to be probed to make sure it is oscillating....still got loads of work to do...and then there's my wife!....

Ed

 

Just a quick update for those that may be following this HK troubleshooting process...The device which I mentioned in my last post as "what I believe may be an EPROM" turned out to be exactly that. I finally got around to peeling the white label off and VIOLA! It was an ATMEL AT27LV010A. For those that may have an interest in this device, the data sheet can be obtained at http://www.atmel.com/dyn/resources/p...ts/doc0548.pdf

A few small updates on the specific troubleshooting process to date: The 16.934 MHz crystal is oscillating...good news! The RAM chip appears to be held in a constant disabled mode...this is not necessarily a bad observation. All pin voltages on the RAM chip appear normal for this mode of operation. A quick look with an oscilloscope at the EPROM reveals that it is being addressed approximately once per second. This would tend to indicate that the CPU is at least partially functional, however more probing of the EPROM is required to fully check out all the lines. More as it becomes available.....

 

Keep up the good work!

 

Any luck fixing the Amp. Mine finally quit. Actually is cutting on/off mostly off. you can hear pops when the amp cuts off.

 

Hi Juan,
Actually, I haven't been putting in as much time on the amp as I would like to. The work load has picked up considerably at my place of work and I haven't had much "free" time to work on the troubleshooting effort. However, the financial aspects of this issue (cost of a new or used HK amp) will keep the pressure on me to find the time and start the effort up again. I hate driving around without my radio...

I'll start updating this thread as soon as I have additional troubleshooting data to report.

Just as a point of curiosity, what year is your Mini? Mine is a 2004.

 

Mine is an 04 as well. Do you have the equipment for troubleshooting at your house or work?

 

I have limited capability at home. I can do the following at home:
1. I can issue the K-Bus commands and read back the resultant response from the amp.
2. I can make ohmmeter measurements which allows me to do continuity tests. This is useful for recreating (reverse engineering) the schematic.
3. I can make DC voltage measurements which provides very limited troubleshooting capabilities. Most measurements require a scope because of the dynamic nature of the signals. However, all of the DC control lines can be (and have been) tested using the voltmeter on the few DC control lines that turn the amp and audio on and off.

At work I have oscilloscopes and microscopes available which allow me to do much more detailed troubleshooting for proper functioning of the amp.

 

How much of the schematic have you been able to reverse engineer? I can help if you if you want. If I remember correctly this PWB is either a two layer or four no more, I think it was two. I need to pull it back out of the car since it finally broke. As far as trouble shooting all I have is a multi-meter. At work all the equipment I need from freq. generators to solder flux but cannot be used for personal.

Have you check any local DC to DC converters? I am sure there is at least one to bring the voltage down for the ICs operating level. What my amp. is doing is shutting off and then back on until it eventually shuts off and decides to work again later on or the next day and the cycle begins. I don't think is the output amp since they work when the unit is on. I am wondering if there is a protection circuit been tripped or failing, shutting the amp off. These units are always on they do not shut off when the radio is off.
I think you mentioned in previous post that all the control signals from the head unit are been send and appears to be working. Have you been able to determine if any of this signal is used to turn the outputs off?

 

a) I have most of the input DC control circuit schematic completed, the area around the K-Bus transceiver IC and a small portion of the circuitry going to one of the CPUs. I am using VISIO to create the schematic (part of MicroSoft Office Pkg). I have anotated the schematic with voltage levels and signals where measured.

b)Yes, have checked out the DC to DC converters and they all appear to be working OK in my unit.

c) I agree with you that it is most likely not the output amps. I am speaking from experience with my amp only.

d) From what I have read about the HK amp there is a fair amount of protection circuitry built into it. At least from the standpoint of my amp the problem seems to be associated with the ability of my amp to respond to the initial K-Bus command that is send from the head unit indicating that it was just turned on. The amp is supposed to immediately send back a response followed by initial settings from the head unit. These initial K-Bus input signals are either not being recognized or the responses can't be generated if they are being recognized in my amp.

e) This is correct, the amp is always on in a low current "listening mode".

f) There are 3 input control lines that on my amp all appear to be functioning, at least up to the point where I was able to trace them. These control signals are:
1. Pin 15 - ON from radio (head unit)
2. Pin 10 - Exhaust Temp. Sensor...I have no idea what this control line is for or where this sensor is located and why they felt it necessary to monitor it. I haven't found any data that addresses the purpose of this line??
3. Pin 28 - Telephone Mute...I believe this is used to mute radio audio when the telephone is in use and passes audio to the amp from the telephone.

g) My troubleshooting process to date has focused on the easy DC logic paths first to make sure that the control lines were "wiggling" the lines up to the point that I could trace them. My next area of concern was the K-Bus transceiver to make sure that the signals were getting to it and it was in turn sending them on their way to their destination (which presently appears to be one of the CPUs). The input signal is getting to the CPU, but the return line to the K-Bus transceiver shows no activity at any time, and as best as I can tell the return line is also coming from the same CPU. The next area of concern was the DC to DC Converters which all appear to be working. Additionally, I have checked out the CPU oscillator and it is functioning as well as the voltages around the RAM chip and the EEPROM which appear to be normal. As to your specific question regarding the ability of the output amp being turned off by way of a K-Bus command, it appears that there are K-Bus commands that will "disable" the amp output during the initilization process.

It surely would be nice to have additional effort being put on this project and I would be more that happy to pass along everything that I presently have regarding my effort up to this point. If you like you can PM me with an email address and I'll send you my VISIO file, or I can make a image copy of it if you do not have VISIO.

I think it would be of great benefit to you if you also were to look into the circut that is available for interfacing to the K-bus so you can send and receive the K-Bus signals. I built this up as the first stage of starting my troubleshooting process. Additionally, there is a software package that you can install on your computer that will provide you with the ability to read out the messages on your K-Bus in your car and send messages as well.

I believe it is importand for you to know if the issues you are having are internal to the HK amp or possibly might be the result of some corrupted communication that is going on with the K-Bus. Or if the symptoms you are having are associated with some normal K-Bus command that is being sent to your HK Amp. If you are interested in going this far with your effort, I can pass along all of the information to you regarding the interface unit and the S/W for your computer.

If I ever get past the point of this troubleshooting effort, there are some very interesting things that have been documented on the Web regarding the use of the K-Bus for control in your Mini. You may also find these interesting and if you already have the interface board built up you will be well on your way to implementing some of these MODS later...just a side thought.

It would be great if your HK amp was responding to the initial K-Bus signals as this would be a tremendous assist in knowing exactly what lines are being "toggled" by the CPU and what involvement the RAM has during this exchange of K-Bus data. Unfortunately all I have at my end is a "broken" amp, so I really don't know in most cases exactly what I should expect to see.

 

Still have that amp for sale? Id pay $100

 

Still have the amp?

 

My '04 MCS amp died yesterday. it used to "THUMP!" every now and then, right after starting th ecar and driving out of the parking garage. Then, two days ago, the sound cut out a couple times for a few minutes, but everything was working on the head unit. today, the head unit still works, but there is no sound. Guess I'll check the boneyards for an amp.
And, Liquid Yellow, you are amazing! What a wonderful thread! informative, educational, and entertaining! Tahnk you so much for all your work and documentation!!!
-Fred (PIXEL)

 

Let me know if you find any Mini's in a salvage yard, been looking...

 

Here's the part...I just need another $935 and I'm good to go! UGH! http://www.realoem.com/bmw/showparts...07&hg=65&fg=25