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Bowers and Wilkins A7 How to disassembly the unit

I have a B&W A7 wireless speaker box and I can not power on the unit.

The unit was working very well for long time and few weeks ago stop to work. Apparently this is a power supply problem because no current is draw for the 120VAC (Totally open circuit measured in the power outlet).

I need to troubleshooting the power supply, but I need to open the unit case to do that and after a very detailed inspection I can not see how to open the unit to have access to circuits inside the A7 wireless speaker system.

So, I need some help to tell me how is the procedure to open the B&W A7 to have access to its power supply to repair it.

Thanks in advance for any help

Best regards Marcos Silva

Answered! View the answer I have this problem too

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well, that is really interesting

I have something similar

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I have the same problem too.

Can someone help us please?

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I have the same problem too. No reaction yet?

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I successfully opened an A5, I think it's the same as the A7. As I posted below, after holding the 4 clips outwards, insert something strong, wide and very flat (think kitchen utensil metal egg flip) in the gap between where the bass outlet is and the fabric cover. Then slowly work them apart and the fabric piece will separate from the unit. IT'S VERY DIFFICULT, so don't think you can get away with doing it quickly and easily, be careful or you can easily damage the fabric unit.

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Hello guys!

I have a problem: after the voltage jumped in the house, my A7 does not turn on. My question is: can it be only a fuse (or preventer, I don’t know exactly how it will be in English) that can be replaced? Or i need to change the entire power component? Is it worth it then to change it (the service takes about $ 120-150 for this) or is it better to sell for parts and buy something new? My A7 is almost 4 years old. Thanks!

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It was impossible to find information about how to open it .... After a analysis of the box much searching the I managed to open it and I'm putting photos of how to proceed. You have to put a protection so as not to hurt the protective cover and to move a cover with a screwdriver inserted in the holes ... I hope the photos help because it is difficult for me to explain in English the procedure. Power supply completely damaged... several components ....

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oh, thanks you very much.

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How can I reach the crew holes, after removing rubber ring screw holes are sill covered most part. How to move the speaker cover a little bit upwards?

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Thanks for this. I’m trying to repair our aux input and couldn’t figure out how to open the %#*@ thing.

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Could you show me how i can do that with the B&W A5. I can't take off its cover. Thanks

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Insert something thin and wide between the fabric cover and the hard plastic above the bass hole. SLOWLY draw them apart being very careful to not damage the fabric cover. Don't go more than 3 cm, there are 2 thin cables attached to the cover that need to be taken out of their connectors.

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Okay, this has been a productive project for me, I bought an A7 on ebay because I like them and well if you can’t open it you don’t own it right. First thanks everyone for the good information. Second here is a link to a legible copy of the SMPS schematic page.

https://www.abcelectronique.com/forum/at...

ISO14000 is a great help and the schematics are essential though only of the power supply. His forum is in French but a few posts are English and the best images of the schematics are there.

https://www.abcelectronique.com/forum/sh...

An important post on the French forum is #80 a link to the photo from that post is below, again it is for power supply test.

https://www.abcelectronique.com/forum/at...

I recapped my power supply before I found post #80 so I am not sure that it was failing but the power board is good now, very gratifying. I used 3, 40 Ohm 50W resistors for the loads.

I still have a problem and a photo, I will get to that. The symptom I have now is, with the A7 assembled, if I try to power up there is no response (no LED) but if I hold the power button and apply power then the LED is solid white, for a functioning A7 that means firmware update mode. The unit does not respond to any attempt to connect with a MAC or PC, however. Still maybe it is progress.

I am working toward replacing some/all of the SMT electrolytic capacitors and while inspecting I thought I could possibly see some slight bow on the top of one cap on the DSP/Amp board.

On the underside near the suspect cap I found a damaged SOT-23, Q45, marked “W3K”. Note the tiny crater where it should read 33. I am going to remove both Q44 and Q45 to try and identify the part so I can order some. I have searched online SMT part marking lists and found diodes with “W3” but no “K“. I will draw a schematic of that section of the board as well for grins.

Does anyone have a clue what cheap SMT SOT-23 part was marked with “W3K“ circa 2014?

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@sunnyjim : This should be what you are looking for,

https://assets.nexperia.com/documents/da...

W prefix for part that is made in the china factory. Marking is 3K.

Hope this helps.

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@pukiima That is awesome I totally did not expect your rapid response, many thanks.

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Unbelievable a $0.40 PNP transistor fixed it. Maybe the power supply board did have a problem as Q45 obviously overheated and it is involved in supplying 3.3V to the DSP. Thanks again for the incites everyone.

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I came across this post by Marcos Sliva and it took me a while to comprehend the procedure of separating the grill fabric cover and the main chassis. It did help me to take apart the my unit and I thought I could help to expand on his post.

The grill cover wraps around the main chassis and it is inclusive of the brushed metal piece on top, the main chassis is everything else beneath. As Marcos Sliva post, begin by removing the rubber feet surrounding the unit.

Next find something similar to guitar pick and insert in between the catch holding the grill fabric cover and the main chassis. There are a total of 4 catches located in front and back of the unit. Then place the unit front side facing down, it would help with the next step.

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Find flat wide sturdy tool ( I used a metal ruler) that can slot in between the fabric cover and main chassis, the position is located above the bass port(hole). With the tool in place, turn clockwise or whichever way to separate the cover from the main chassis. Move along the seam and gradually separate the two parts taking copious care not tear the delicate fabric cover. 2 parts can be separated easily when gap is sufficient to use fingers , taking care to disconnect the ribbon cables.

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My unit was experiencing some issues before it failed to power on. Previously, the unit will connect to WiFi for 20 ~ 40 minutes upon insertion of power cord, afterwards Airplay will not work and/or the purple light will flash. Airplay still works by connecting the unit to WiFi router via LAN cable and power cycle the unit by removal and reinsertion of the power cord.

Unit died few days ago and disassembly of the was done with help from initial post by Marcos (Big thanks!). Upon closer examination, it was found that a number of filter capacitors had high ESR. The original electrolytic capacitors were from Su’scon and have been in service for 7 years and was replaced accordingly. Unit is now back to full functional status.

List of capacitors replaced on the PSU board, i suspect that A7 shares the same PSU as the Zeppelin due to its elliptical shape.

  • 3 x 1500uF 10V
  • 1 x 100uF 35V
  • 1 x 22uF 50V
  • 6 x 100UF 16V
  • 6 x 220uF 25V

The SMD capacitor located on the WiFi board also exhibited high ESR and was replaced. It is the only SMD electrolytic capacitor on the WiFi board

SMD Capacitor marking

100A

WZ

  • Nichicon WZ series 100uF 10V

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HI all

I’m ISO14000 from abcelectronique dot com.

Thanks in return for the “how to open the A7 BW” …. worth than an oyster without a good knife

best regards

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hi, is there a way to contact you directly? thanks

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Hi Dominique…

I’m the guy in France that try to polish BW brand to a good repair level . I’ll be very happy to help you in fixing your A7.

Contact me via the abcelectronic forum in pm. regards!

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thanks, will do

However for an unknown reason the A7 works again ! This is the second time it happens... I will contact you next time it breaks down, I know how hard it is to diagnose an intermittent break.

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Hello, I tried to lcontact you but apparently I did not find the right way, Any other way to get your help? After having worked (beautifully) for a few weeks, the A7 is dead again...

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Hello I have the same problem with my A7 but I am not good enough at electronics to even think of repairing it myself… Any idea what to do, where to send it for repair ? B&W says it is over 5 years old and does not want to try repairing it !

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Hi Dominique, You may be in luck there is someone, in France, that repairs them. Apparently there is a very common failure for units used at 220V. I think the best way to contact him is to go to abcelectronique dot com and send a direct message to ISO14000. There is a thread there which he contributes to often and he requests people to contact via DM.

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I could not reach him.... any other idea on how to ?

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@sunnyjim @pukiima

hi,

what my a7 does is - a slight buzzing when switched on, then there is a fast red led flashing. B&W said it can be power board failure or main board failure, but they dont sell spares anymore.

Any idea what issue it can be and if it can be fixed?

thanks!

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My issue with A7 power board has been solved by a repair done by abcelectronique dot com and a direct message to ISO14000. He did a fantastic job and my A7 works again

Dominique

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@dominique turcq hi how much it costs? thanks

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hi,

is it possible to fix webbing on that photo (Attached) thanks https://imgur.com/a/abto6Vq

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Marcos Silva will be eternally grateful.
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