Soekris DAC damaged by static

good day diy audio

i have been happily using the soekris dac (dam 1021) for a few years now

*see attached pics

unfortunately, yesterday, a static discharge ( walked across the carpet and touched the metal volume knob) caused an audible pop,
and now i cant get any sound through the dac :(

when i replace the dac with another device, all works fine. so unfortunately it is the dac that was damaged

is this fixable?

any ideas where to start re troubleshooting?

much thx

sw
 

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Usual approach would be to visually inspect the board for any signs of damage or bad smell, measure all power supply voltages, and look at AC signals with a scope. When a needed power rail or signal goes missing, that can be a pretty good clue where to take a closer look.
 
99% of the time with ESD, the component damaged is connected to the outside world. So, look at input and output devices. If the knob shaft was isolated and only connected to something inside, look there too, but that would be rare.

Sigh, a nice unit like that should be better designed. This is not a new problem or one without SOP solutions. If the discharge from domestic carpet causes a failure, I totally, totally blame the designer. For instance, you can go to AMD/Linear Tech site and see all the recommendations surrounding a USB port . Similarly look in application guides for op-amps.

A mitigation hack is of course, some to though before the equipment, but that is only a hack for bad design.
 
Some ESD suppressor should be used for USB. Don't know if Soekris boards have them. I'm using ECMF02-4CMX8 in my USB-I2S bridge.

According to the schematic Amanero has ESD suppressors diodes for DM and DP. So USB probably is not the source for ESD in this case.
 
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hey everyone, thanks for the feedback...

the volume pot was mounted on a piece of aluminum that was fastened to the wood base

the volume knob was aluminum, mounted on an aluminum shaft

room temp and humidity have been the same for years, this is the first time ive had any esd issues

all the voltages from j1, j2, j3 appear to be normal

the 3.3 iso shows up on j3 when the amanero usb is connected to a source ( intel nuc in this case)

when a source is connected, usb or spdif, the sync light stops blinking- as it should

the dac connects to the set up/ manager software via a serial cable. and i was able to download and update the firmware
(running 1.21 as i was before)

using a spdif connected to eliminate the amanero as the cause produced no sound from the output

the unit worked fine for a number of years, it was powered by a custom linear ps that included some very nice audio note kaisei filter caps

the only other issue ive ever had with this set up, is the dac stops playing sound momentarily whenever the house ac turns on, or if a vacuum turns on, etc..
any type of large current/ transient surge. but ample current supply coming into the house

and the ac socket for the system is separate from everything else

ive reached out to soekris, as i ve heard very good things about him and his product support, so if i cant figure this out, then i hope to send it to him for his assistance.

cheers

sw:)
 
Good news !

My wonderful Soekris DAC is alive again

The manufacturer advised that since the usb and the spdif inputs produced no sound, and yet all else seemed okay, its likely that the brain-
the FPGA, has been fried, and to replace it is not cost effective/ not practical

Based on that advice I was ready to toss it in the trash when I decided to do two things..

1) upgrade FW to the latest 1.23 and 2) remove the volume pot I had connected and revert back to the fixed volume setting

And it came back to life !

The manufacturer now believes that the FPGA was not fried after all but in fact only the part that the volume pot is connected to (uC)
was damaged by the ESD hit

So likely, just resetting to fixed volume- bypassing the pot, would have fixed things.

When faced with a very pricey option of getting a new board, Im very glad I didnt give up so quick.

The Soekris lives on :)