I also tried fixing a wifi/logic card, but was unsuccessful. I had one card that showed a dead short, and another that had a bad NAND chip. I moved the NAND chip from the card with the short to the other card, but it wasn’t recognized. It turned out that the good chip was ‘legacy’ and was a 64MB chip while the other NAND that it was replacing was ‘modern’ and was 128MB. It gave a message of ‘no NAND found’ in the UART, so I’m pretty sure it just doesn’t recognize the chip.
I looked closer at the boards. The two boards did have different DRAM and NVRAM (with the ‘modern’ device having twice the capacity of legacy for both DRAM and NVRAM). However, they did have the same ROM chip (the 512k EN29LV040). So in addition to moving the NAND chip from the legacy board to the modern one, I moved the ROM chip too. After this, the logic card booted correctly!
U-Boot 1.1.1(1-16-3-0.9), Build: 0.9
MPC8272 Reset Status: External Soft, External Hard
MPC8272 Clock Configuration - Bus-to-Core Mult 3x, VCO Div 4, 60x Bus Freq 16-50 , Core Freq 50-150 - dfbrg 1, corecnf 0x10, busdf 3, cpmdf 1, plldf 0, pllmf 3 - vco_out 400000000, scc_clk 100000000, brg_clk 25000000 - cpu_clk 300000000, cpm_clk 200000000, bus_clk 100000000 - pci_clk 33333333
CPU: MPC8272 (HiP7 Rev 14, Mask unknown [immr=0x0d10,k=0x00e1]) at 300 MHz Board: Sonos Wembley DRAM: 32 MB DRAM test Test complete - 0 errors, error pattern 00000000 Using default environment
In: serial Out: serial Err: serial Net: FCC2 ETHERNET Hit any key to stop autoboot: 0 NAND ID is 20:75 32M NAND flash (ST NAND256W3A) S0 provisionally good, KP=1, G19 S1 provisionally good, KP=4, G18 Boot from partition 1 ## Starting application at 0x00400000 ..▒TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT...........................…
It is only recognizing 32MB of DRAM despite the card actually having 64MB, but that’s what I would expect given the ROM and NAND chips came from a legacy device that has only 32MB.
I’m definitely a happy camper, having salvaged a working logic card from two previously dead ones! here’s a pic of the board after I swapped the NAND chip (but before I swapped the ROM)
I am glad that I figured out after reading all the other posts in this thread, it is really helpful:
It turned out the burned PCB indeed destroyed one of the traces from the rise card to the 3 pin diode. I could not really visualize it but the meter told the truth. I removed two capacitors and solder a thin blue wire as you can see in the picture.
With this fix and as soon as I start playing music, I did get 36V and the white/orange flashing is gone.
It is amazing with such bad burn in the inductor that the PCB got a hole underneath it but no other components were damaged including the fuse!
Thanks again for this informative thread.
That's some sketchy paranoia right there.
That was it! I replaced the shorted diode with a 1n4148 as that's all I had on hand. No more orange light and she sings!
I have to thank everyone that participated in this thread, wouldn't have gotten her working without your help.
, but this unit was water damaged and my guess is that it was probably rusted out.
At this point I recommend a thorough cleaning of everything. Residual from that liquid can cause future trouble. Soda spills are some of the worst because the residue takes on water from the atmosphere and forms acids that can cause unwanted conduction paths and eventual trace and component failure.
I forgot to attach images to my previous message. Here they are… the mosfets are marked in red boxes.
Fantastic - Nice job!
All. voltages seem good EXCEPT I never get 36V between GND36 and 36V it sits at ~15v. When the volume is turned from 0 to anything I get a blip of sound (quick drop to 13-14V) and then orange flashing light, with the volume bar jumping back to ~15%.
I suspected the 14 pin IC on the logic board gruv2ths mentioned solved his similar issue. I swapped the entire logic board with a known good one and same thing.
Where is this 36V supposed to come from? Do I have a switching issue? voltage issue? OR are the amp chips gone? Need a push in the right direction to identify what's failing.
The 36V only becomes active above a certain volume threshold. I found some sonos patent information a while back - this approach is what allows the unit to be low power until higher power is needed (ie when it is actually amplifying), and this is why leaving them on continuously doesn’t create a lot of heat or use a lot of power.
So the 15V you get at the 36V point is ‘normal’ when the device is in standby or at low volume, but when you hit play or turn up the volume then the 36V should come alive and the 36V point should read 36V.
I believe that the 14 pin logic chip is what controls the on/off status of the 36V. That is located on the top logic board. I recall gruv2ths saying somewhere that some of the 36V control circuitry (perhaps a recitifier) is on the riser board. You might try to swap that riser to a known good one and see if your problem goes away or not. Once you have the top logic board removed, the riser just pulls straight up.
I think that if the amp chips are gone, then they could be causing a short that is affecting the 36V. Hopefully that’s not the problem.
Wow, that shot with the light behind the PCB was amazing! Well done!
I forgot about that coupled inductor. That guy conducts ALL of the primary power. One small nick in that mag wire will cause the inductor to blow open and no voltaje, in a very ambiguous way.
So given where you are, primary power restored, i would get a datasheet for the bias converter PWM and get to work. In this thread there are some nice test point references to show you what you should get with a working unit. Take a good look around the PWM pins on the bottom for corrosion.
Pro-tip: the bias converter is a very standard flyback converter. If you google flyback converter you will get something similar to what you have in the AMP. Look closely in the primary winding snubber. Also check the 10ohm high wattage through hole resistor, it provides power to the transformer primary.
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