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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
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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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.
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.
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 10V1 x 100uF 35V1 x 22uF 50V6 x 100UF 16V6 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
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?
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
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!
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 !
@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!
Very interesting information! I am currently working on an A7 that suddenly is unable to connect. When turned on it shows a slowly pulsing red LED, and keeps doing that forever.When I then do the factory reset, it shows a quickly pulsing red LED, and also keeps doing that forever. I checked many different things and described them here: https://bit.ly/3NbCko4 Questions Anyone that recognises this?What next step should I take?Did anyone ever try the recovery utility of the Zeppelin with an A7?
