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.
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.
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.
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?
well, that is really interesting
I have something similar
door Joshua McCarthy
I have the same problem too.
Can someone help us please?
door Thach Do Hoang
I have the same problem too. No reaction yet?
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.
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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