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Connect:Amp repair

G

I’m trying to fix a “no power” Connect:Amp Gen 2 and made great progress - before it all went wrong.

Fix: Fuse was blown and two MOVs on the VPRI/VMID rails were low resistance. I replaced these, reassembled enough to test it, and it booted! The app found it, added it to a room, and then said it needed an update. This went ahead but the unit didn’t come back afterwards.

Current: It powers up (3.3V and 5V rails fine), turns on the white LED for 4 seconds, this then goes off for 18 seconds, and then it repeats. While the LED is off, the Ethernet lights are flashing as expected, so I guess MAC and PHY have been initialised. It will not go into factory reset mode by holding play/pause when powering up.

Theories: 1) it was bricked during the update and I’m screwed, 2) there is a fault elsewhere that the previous firmware didn’t detect but this firmware does. 

I see chat elsewhere about 36V to the riser board, but my reading of the PCB is that the riser just enables the MOSFETS to supply DC to the rest of the 36V supply. My next play is to check the MOSFETs (drive, input, output) but if the bare truth is that theory 1 is correct then I’m wasting my time.

All feedback welcome.

 

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Best answer by buzz 5 May 2024, 17:35

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5 replies

G

I have found shorts on the two dual diodes and I’m going to pull those to better test them and then try again. Previous firmware was reported to boot normally with the TO-220 MOSFETs and diodes removed but then sulk with a flashing orange light when you tried to play anything. Maybe things have changed? Who knows, but I’ll pull those diodes. I can always replace with lower current discrete diodes for now rather than spending time/money sourcing correct part if the unit is irretrievable. 

buzz

Be sure to check the power supply capacitors. Certainly, none should have shorts or “bulged” tops, but this is not proof of a healthy capacitor.

G

I have an ESR meter so I can do that, but %v and 3.3V were spot on and it was booting just fine before it did the update. I’ll check the power/amp board for other issues and then maybe try and get to the UART via a USB adapter to see what’s going on. I suspect the kernel is starting up but then failing due to not finding something (DSP?) but who knows.

 

buzz

@gadgetmind,

Maybe a block of RAM has issues, Since modern operating systems, especially during updates, move things around, it’s hard to predict exactly what will happen while attempting to use a defective area.

G

I guess I need to get a USB serial lead on there and see what it says. 

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