Audio Restoration Repair Bose Wave Music System AWRCC1 AWRCC2 AWRCC7
This applies to the Wave Music System, Wave Music System II, Wave Music System III, in all AC voltage variations.
These particular versions, manufactured in the 2000’s, are designed in the USA, but include a majority of low-quality parts sourced in China, which are the primary source of all the problems. Their parts quality is far below that of the original 1990’s Bose units, which were completely sourced and manufactured in the USA. These WMS units have the front-loading CD player.
Bose refuses to release Schematics or Service Manuals, however, that is not a problem for experienced ethical technicians to reverse-engineer the circuits, and repair them to a higher standard than Bose’s own technicians (based on the questionable quality of the originally-installed Chinese parts).
After reading and understanding this document, any competent hobbyist or technician with good soldering skills may make his own repairs, with a high probability of success, without needing to feel captive to Bose’s facilities.
The normal symptom of this series is weak sound or no sound. Generally, they are able to be switched on, and the display responds to the commands of the Remote Control.
The cause of the problem is massive and widespread failure of all the Chinese SMD capacitors – around 40 of them. For example, 1uF capacitors showing ESR of 20-30 Ω, 10uF capacitors showing ESR of 10-17Ω . The consequence is that the associated IC’s current becomes unstable, and causes the TDA7376 output amplifier and / or associated copper traces around the IC’s, to burn.
There is NO quick and cheap fix, and simply replacing ONLY the burnt TDA7376 (which many technicians of dubious ethics do) is another timebomb waiting to explode, because it is still subject to damaging unstable current and will overheat and fail again in a short time, IF all the capacitors are NOT replaced simultaneously.
Disclaimer – you repair/modify your radio at your own risk. I take no responsibility whatsoever, for any changes / damage you may incur.
These modifications apply to the Wave Music System units with the Front-Loading CD. The applicable PCB numbers (all very similar with minor differences only) are as follows:
283027-001 Main PCB
291619-001 Main PCB
342507-006 Main PCB
269837-001 CD Processor PCB
345156-005 CD Processor PCB
To be certain, open your own radio, and compare your circuit board to those shown below. If it is identical, you can repair/modify your radio with confidence.
This is the early version BEFORE starting work – the CD mechanism and speaker cabinet have been removed.
This is the early version AFTER completing work – the CD mechanism and speaker cabinet have not yet been reinstalled.
On the Main PCB, moving in a clockwise direction, the Preamplifier is at the top left; the TDA7376 Output amplifier IC is at the top center; center right is the 10,000uF filter capacitor and the 4 bridge rectifier diodes for the power amplifier 15VDC rail; AC input at the top right; below is the 2SC1173 NPN, 2SA473 PNP and KSH210 PNP power transistors which produce the Preamplifier 9VDC rail; bottom and center left is the tuner section.
This is the later version BEFORE starting work – the CD mechanism and speaker cabinet have been removed.
On the bottom CD/Microprocessor PCB, the CD section is at the left, and the Microprocessor section is in the shielded enclosure. The early and later versions are almost identical.
When remounting this PCB into the Black casing, it is necessary to mount this PCB 2.5mm lower than originally installed, to allow clearance for the vertical height of the new capacitors, below the CD mechanism.
To achieve this, simply remove the top 2.5mm of the 3 mounting studs on the Black casing, by either grinding off with a Dremel, or melting off with a flat soldering iron.
This is the later version AFTER completing work – the CD mechanism and speaker cabinet have not yet been reinstalled.
The repair/modifications comprise 4 stages.
- Removal of all Chinese SMD capacitors – absolutely essential, no matter what symptoms you are experiencing
- Replacement of all capacitors with Nichicon and Panasonic 105°C Low-ESR electrolytic, and Wima high-precision Film TTH (not SMD) capacitors
- Diagnosis and repair of sound problem – requires DMM voltmeter and oscilloscope
- Replacement of the TDA7376 Output amplifier (if still no sound, after making all repairs)
- Removal of all SMD capacitors
It is a given that ALL these low-quality Chinese capacitors are defective. There is no quick or cheap way to solve this. ALL of them must be removed. The DC electrical current in the machine is completely unstable, and all the semiconductors are highly stressed. One or more semiconductors have already failed. No wishful thinking will make the problem go away.
The large heatsink at the rear of the machine must be removed, to provide access to all the capacitors.
Every technician has his own favorite method of removing SMD capacitors.
My favorite method is to grip the capacitor from above with a pair of pliers, push DOWN, and simultaneously firmly twist the capacitor in the horizontal plane, about 120-180°.
NEVER pull the capacitor in an upwards direction. The correct horizontal twisting action will break the capacitor leads at their weak point, and the capacitor will separate from the PCB.
If this method is done correctly, it will never cause damage to the solder pads on the PCB.
After the capacitor has been removed, you should apply the soldering iron (about 290°C) onto the pads, in order to remove the residual part of the SMD capacitor leads, which are still attached to each pad.
- Installation of new capacitors
The first priority is to restore the normal stability of the DC current in all circuits. Therefore the use of far-higher quality capacitors is essential.
Capacitor replacement is done BEFORE attempting to troubleshoot. In many cases (but not this one), replacing the capacitors will solve ALL the problems, and no further troubleshooting is necessary.
I refuse to use new SMD capacitors for replacement. Current technology SMD capacitors are far less reliable and far more failure-prone than conventional TTH (Through-The-Hole) capacitors.
Each new TTH capacitor must be prepared for installation on the original SMD solder pads. These solder pads suit capacitors with a 3-5mm lead pitch. For capacitors which must be mounted horizontally (due to limited vertical clearance), creativity is needed. Pay attention to mounting positions shown in the previous large photos. For capacitors which will be mounted vertically, bend and cut the new leads as shown in this photo.
- Diagnosis and Repair of sound problem
At this stage, assuming that you have worked patiently and diligently, you should be able to reassemble the machine and test it. You may very well have a working machine again, and with even more fulfilling sound than the original situation, having used far higher quality components.
If the machine is still not producing correct sound, the first place to look is at the TDA7376 power amplifier. There are 15 pins arranged in 2 rows, and the pins of interest to us at this stage are Pin 4 Left input, Pin 1 Left Output, Pin 12 Right input, Pin 15 Right output.
Here, the relevant pins are shown marked in red (with the destroyed TDA7376 removed).
With an appropriate audio signal source connected to the rear AUX-IN connector, these pins are checked on the oscilloscope for correct waveform.
For example – if Pin 4 has a good waveform, but Pin 1 waveform is defective, obviously the TDA7376 is defective, and must be replaced.
If Pin 4 has a defective waveform, then the audio signal is not arriving from the preamplifier section, and the cause must be traced. This was the problem in this case.
The troubleshooting continued as follows in the preamplifier section:
- Scoping the waveforms on the input and output pins of the HCF4052 MPX and TL072 OpAmp IC’s on the bottom of the PCB. A completely defective waveform showed an amplitude of less than 1mV P-P on all these components. That told me that these IC’s were not performing correctly.
- I decided to check the VCC and VSS pins for correct voltage. The VCC showed less than 1mV DC. That told me clearly that the DC Voltage rail is defective.
- I disconnected AC power, and traced back through all the Via’s, to the source of this Rail, which is the Collector of the KSH210, and checked the components in this area. All checked just fine, with no shorts, or abnormal readings across the pins.
- I then reassembled the PCB and connected power, and checked the KSH210 Collector again – Zero Voltage. I checked the KSH210 Emitter – Zero voltage. Not good. I checked the Emitter of 2SA473 – good voltage. Aha!
- There is the EXACT problem – Cable break between 2SA473 Emitter to KSH210 Emitter. I connected my spotlight and magnifying glass and found a bit of black soot at the position shown with the red arrow. I scraped away the black soot, and discovered the break in the copper tracing.
- That is a direct consequence of the original Bose low-quality capacitors failing and causing the KSH210 to become stressed, and burn its surrounding traces.
- I bypassed the damaged trace with a new wire, from the Via direct to the KSH210 Emitter.
- I then reassembled, applied AC power, and checked the KSH210 Collector – 9.1VDC showed. Good progress, but not the end of the story.
- I then reapplied an audio signal source to the AUX-IN, and scoped the TDA7376 input Pins 4 and 12 – clear and proper waveforms, which means that all the preamplifier IC’s are fully operational.
- Problem solved. This was clearly a case of the original Bose Chinese capacitors causing collateral damage, well beyond the actual failure of the capacitors themselves.
- Installation of the new TDA7376 Output amplifier
I installed a new TDA7376 output amplifier, and reassembled the machine. Excellent sound.
Parts for this restoration
Parts and advice are available for owners who wish to tackle this project by themselves.
Mr Yachad own and operate CondorAudio in Jerusalem Israel, and restore/repair Vintage Electronics, and modern LCD/LED TV’s and other equipment. He has a fully equipped lab to handle the most demanding projects. He service customers from all over the world, especially reviving equipment at the “Component Level” that other technicians do not know how to repair, or declare “Parts no longer available”.
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George Nutzul
October 16, 2018 at 12:26 pm
Thank you, Mr. Yachad, for your excellent article on servicing the Bose Wave systems, and sharing your knowledge with us. Its unfortunate that a world-renowned company would cheapen an excellent product by using inferior components. I hope myself and other technicians can save a lot of these units, and restore them to better than original condition!
Thanks again, and God Bless!
Robert Calk Jr.
October 16, 2018 at 12:38 pm
Nice work, Mr. Yachad. I have a newer Bose surround sound system that my TV sits on, but it doesn't have a CD player or anything. It sounds great. Sometimes it sounds like the people are behind me talking. And sometimes when a dog on the TV is barking it sounds like the dog is outside barking.
One of these days I'll open it up and look everything over good.
Albert van Bemmelen
October 16, 2018 at 2:11 pm
A real Bose repair pro at work! After reading about all those 40+ terrible quality capacitors and your special method to grip the capacitor from above with a pair of pliers, pushing them DOWN, and simultaneously firmly twisting the capacitor in the horizontal plane, about 120-180°, is making me wish never having to restore such a defect model of this type of Bose. The time involved and the risk not being able to successfully finish this repair makes this a very dangerous repair to begin with. This requires a courageous expert like yourself!
Robert Calk Jr.
October 17, 2018 at 4:08 am
Twisting them off like that does work pretty good, but I don't like to do it. I can't afford to buy the tweezers for my iron right now, so I would just use both of my irons to remove them real quick.
Parasuraman S
October 16, 2018 at 3:07 pm
Very detailed, step by step explanation of troubleshooting of a very complicated audio system. Very educative article. Very time consuming work as well as article. Many thanks for sharing!
AdamS
October 16, 2018 at 3:57 pm
A good article and a depressing indictment of Bose's "quality".
However, I personally don't like the idea of simply twisting SMD components off the board. I usually remove them using a very fine solder tip on my iron by melting the solder on one end of the component and making sure it is well heated, then quickly moving the tip to the other end and carefully 'sliding' the component off its pads. If you're quick enough the solder from the first end is still melted and the component will come off easily.
Parasuraman S
October 16, 2018 at 11:04 pm
Yes, I follow this for small SMD components.
Humberto
October 17, 2018 at 1:15 am
Great job, good images and everything detailed step by step.
Henrique J. G. Ulbrich
October 17, 2018 at 1:35 am
Very very good, Mr Yachad. Thanks for sharing. I´ve learned something more.
Rey
February 8, 2019 at 12:33 am
Hi, I need help on the bose acoustic wave music system series ii, with green backlit lighted up on the lcd panel but no display of info and details. I heard this has gotta do with the capacitor as well. Can experts help please?
Helpless Hanna
August 23, 2019 at 5:51 am
This is really fantastic information, however I am a total mechanical imbecile. What I need is one of you technicians. How do I find you? I miss my Bose so much.
Graham
September 15, 2019 at 8:19 pm
Thank you so much for this.
Not sure if I am capable of the repair but I'm inspired to try having read your excellent description. Many many thanks.
Graham
September 15, 2019 at 10:34 pm
Are you able to provide a parts list please?
Robert A Smith
October 14, 2019 at 1:04 pm
Do you do -- or recommend a source that can do -- this: Repair or replace the CD player unit in a Bose Acoustic Wave system. My unit has begun to play one note of a song only, then begin clicking repetitively. I can forward to successive music cuts, but the same thing happens. Usually I have no problem with the machine "swallowing" the CD, but that has happened in the past -- requiring much effort to recover a disk.
Bose Ser No 033975C63260057AC
Bob Smith, Cedarburg WI 53012
Brantley
April 27, 2020 at 10:34 am
Thanks for your detailed explanation on replacing the capacitors. I having the same problem as Robert Smith which is dated Oct. 14,2019. Unit plays a couple notes of the cd selection then starts clicking repetitively. The way I’ve found to listen to the unit is to insert a cd cleaner disc(max cell cd-340) before inserting the music cd. I let the cd cleaner run about 10 minutes or until I no longer hear the repetitive clicking then remove it and insert the music cd. The music cd then plays fine and all cd’s after this procedure until I turn off unit for a few hours. After a few hours I have to do the same procedure again before cd’s will play. This procedure has worked at least 10 times and ,so far, is the only way I can listen to cd’s. Care to venture a possible cause or fix for this odd problem. Brantley Poss
Rich
May 26, 2021 at 10:16 pm
You have failing Capacitors that when heat up change their value then start to work within spec.
Once they cool down after powering off for a while it will no longer read the CD's properly.
By allowing it to keep failing for 10 minutes the components heat up and allow them to get in spec again.
Most likely the caps on the 269837-001 CD Processor PCB.
Infiniti25
October 17, 2020 at 11:49 pm
Wondering if anyone had the list of components, specifically capacitor type and values, needed for this repair?
I have the clicking/skipping on the CD player, and from cold start it is even flickering the LCD off for a second as though power is being requested and it’s not getting enough or not stable power.
I’ve seen a listing from the author of this article on EBay but to import the parts using that listing would be more than paying someone else to do the work for me.
Mukesh
October 25, 2020 at 10:03 pm
Shame on BOSE.. $500 system with cheap quality components. will rather throw it than giving it for repair to BOSE.
Jo
June 2, 2021 at 11:19 pm
I have a Bose Wave system in need of a new IR detector. The sensor replacement part recommended in the forums is IR detector 38kHz TSOP4838. Many people have had great success replacing this part. My issue is this recommended part has 3 pins. My sensor has 4. Can you recommend a 4 pin sensor please?
Andre van Swaaij
November 1, 2021 at 5:07 pm
Thank you Mr Yachad. Watt a great, detailed tutorial. It helped me a lot. I have a very similar problem: 9V rail no power. But in my case the trace to to via that you indicated was intact. I measure 15V on the emitter of the KSH210, but also on the base, so it is not driven. On the extremely tiny driving NPN transistor, I measure 2.7 v on the base and 2.3V on the emitter. Not sure if these voltages are correct. I do not have the tools to remove such a small transistor, so I decided to remove the KSH210, and apply an external 9V supply: the unit then works perfectly so the failing 9V is the problem. I cannot find a schematic of my unit anywhere: PCB 291619-001, unit model AWRCC3. Does anybody have a schematic so I can trace further, or maybe suggestions where to look at? thanks a lot and greetings from the Netherlands.
David
December 13, 2021 at 2:54 am
Hi. Would anyone please be able to check on their boards what is the value of a thermistor rt2 located behind the mains power plug. Schematics not avilable. Hopefully someone here can help.
Anonymous
April 22, 2024 at 4:42 am
On a AWRCC2 radio it shows 450, 145V.
BC, 3R8 on other side.
Not a spark chaser so good luck.
Stephane
December 27, 2021 at 4:29 am
Hello @ van Swaaij
I have exactly the same problem .
ie 15V on the KSH210 instead of 9V
Have you found the fault and a schematics. I have the same PCB as your Bose
Regards
Stephane ( France)
Stephane
December 29, 2021 at 4:34 am
Hello
Finally I found the problem.
Near KSH 210, there was a link cut between the 100ohms resistor and the MMBD4448HCQW (marking code KA4 SOT 363) which was due to the oxidation of the copper track which was cut.
After repairing the cut, everything works perfectly!
tns
June 25, 2023 at 2:20 am
Have the same symptom but no broken trace. The sot-363 near the KSH210 is more likely a DMMT3904W, at least on the AWRCC1 model.
tns
June 26, 2023 at 9:34 am
On my (no audio) unit the base of KSH210 is not being pulled down but instead stays at the rail (16.5v). The nearby NPN responsible for doing that (dmmt3904 code K4A) does have a Vbe=0.7v when the radio is turned on, but it acts like the collector is open. Pulling down the base of KSH210 directly thru a 1k turns on the sound, confirming that the all the other audio circuitry is OK. Parts ordered.
tns
July 1, 2023 at 9:33 am
After replacing the DMMT3904W, everything works. Replacing this tiny sot-363 takes some skills. Good eyes or magnifier, a steady hand, flux and a fine tip iron.
Beetle1303
July 3, 2023 at 4:39 pm
I am so glad to found this tread - I have the exact same model and exact same issue. I have just ordered the same part#, and some smd component soldering tool and material.
One question - does the VFD display works prior to KA4 component replacement?
Thank you.
tns
May 4, 2024 at 12:14 am
It has been awhile but I don't think the display lit up without KSH210 being on.
tns
May 4, 2024 at 1:45 am
AWRCC1, early version (1st board pic above).
I thought replacing the DMMT3904 had fixed the KSH210 power issue but even though the unit now powers and plays I have a background hum on FM.
I now see the collector of KSH210 is up at the 16v rail instead of the regulated 9v to 12v range required by the preamp IC. I am trying to trace out this
circuit to see how it is supposed to regulate, but keep finding more parts involved. Has anyone traced this out?
Kazam
December 17, 2021 at 12:35 pm
Need schematic for bose awrcc1, lcd no display pin16 shorted to gnd
Beetle1303
July 4, 2023 at 9:42 pm
I have the same issue - I am curios how you ascertain it is shorted to ground, and what it should be without having the schematic?
Anand Prajapati
December 24, 2021 at 6:38 pm
Thanks for the detailed inforamtion. Could you please share me the part list as i have same problem and would like to solve this myself like you.
Solo
January 1, 2022 at 6:49 am
I pickup one from my neighborhood with the continuous message on display "PLEASE WAIT" I replace all the caps on the processor board and now works beautiful, Thanks
Grant
February 5, 2022 at 8:35 pm
Thanks for the detailed information. Could you please share me the part list as i have same problem and would like to solve this myself like you.
Andrew Bown
February 14, 2022 at 2:33 am
Hi what a great guide and we’ll explained. I have a boss wave iii, do you have the parts list for that.
Many thanks Andy
Trev england
March 6, 2022 at 10:56 pm
I have a Bose wave which only has a problem on cd start up ,missing cd skipping etc. I would like to try and repair it myself and am prepared to replace the capacitors on the board 269837-001 you say you have the parts to do this are they available and at what price and how do I recognise the correct ones as the numbers and codes seem complicated
Here’s hoping you can help.
marioer
June 22, 2022 at 5:31 am
Thank you for very helpful advice and tips on repairing this equipment. Greetings from Poland.
James Anderton
January 9, 2024 at 12:18 am
Great info the problem with these Bose units.Can you replace the capacitors in these units.I have one that needs to be repaired.I'm old & can't see well enough to soldier any more.Thanks for great knowledge James Anderton. Please respond
Phartlyps McClanahan
March 5, 2024 at 11:11 pm
Thank you Mr Yachad. It was exact problem in my unit - A burned out trace. What a shame for Bose, a good name marred by cheap parts. New parts are on the way!
You are a man of deep honor!