Presonus Audiobox 1818VSL firmware dump

[Khron]

This is probably very much a "shot in the dark", but i have to try. Presonus support have been... well, let's just say, "less than helpful" 

The bulk of the story:
https://khronscave.blogspot.com/2019/03/37-presonus-audiobox-1818vsl-teardown.html

I did some more poking around tonight, and there's absolutely squat re: clocks on the ADC/DAC chips (ie. MCLK, LRCK and BCLK / SCLK).
Reasonably sure that's why the Vcom and the Filt+ voltages are almost-zero-but-not-quite on the CS4272's, but the /RST are high, so they're not being held in reset as such.

I reached out to kingkorg here just now, after discovering by total chance that he had an 1818VSL in use, but alas, doesn't have an SPI flash reader/programmer, nor can he gain access to one.

So i'd be reeeeeeeeeeeally grateful if, by some miracle, someone 'round here happened to have an 1818VSL and had the means and the kindness to desolder the firmware chip, read it out, and send me the contents (one way or another) 

 

[cyrano]

Don't have a Presonus around, sorry.

But I'd recap that PSU. I've seen it with MOTU, RME and Presonus that a faulty PSU gives the kind of problems you're experiencing. Like connecting, but not sending audio, or connecting and locking up or other weird behaviour.

Did you measure PSU voltages?

 

[Khron]

I did the recap in the mean time, yesterday, also in the hope that maybe the CPU needed some big gulp of power for the firmware update, and the supply rail craps out, but no, that didn't help.

All the small green electrolytics were on the 5V rail, for what it's worth. One of the two fatter black ones was on the 1V rail, the other on the 5V rail as well, but on the input of the linear 3.3V regulator.

I also identified one of the two little chips right next to the CPU - the MSOP-10 packaged one is a CS2300-CP PLL / clock multiplier.
https://statics.cirrus.com/pubs/proDatasheet/CS2300-CP_F3.pdf

I'm quite sure the SOT23-5 chip right next to the 13MHz quartz is a humble logic gate, which creates an oscillator using the quartz, feeding into the CS2300. That one's software-controlled though, and there's sod-all coming out of it, hence no clocks for the ADC/DAC chips. Haven't managed to figure out what the smaller 8-pin one is, though (marked "CNAA" or "CHAA", and "NZ17" on the second row), possibly some sort of buffer.

 

[Khron]

Well, i ended up finding a working unit for a reasonable price locally (180eu) and, sure enough, "cloning" the firmware to my first unit brought it back to life instantly! ;D

Or, well, as soon as a couple of my brainfarts cleared the air... :

http://khronscave.blogspot.com/2019/05/42-presonus-audiobox-1818vsl-revisited.html

 

[kingkorg]

Great read!

 

[Khron]

You're too kind, and flattery will get you nowhere! ;D

I'm just glad i managed to revive the damn thing - no thanks to Presonus' support department.

Just for the hell of it, i opened an add-on to the closed support ticket i had opened about this problem, with the "bought, cloned, fixed" short story, and a stark "Thanks for nothing." added.

As a contrast, Focusrite's spares department agreed to send me free of charge a few spare screws and plastic button-covers for a Scarlett 18i20 i got from a local friend, after i asked whether they could and how much it would cost. Those should arrive this week

 

[cyrano]

Now, where's that smiley for applause?

I agree, FR support is great. Presonus isn't bad either, but it's a bit less down to earth. More sticking to idiot rules.

D&R is great like that too. They still stock most of the parts for their old desks and if you need a button or such, just ask...

 

[Khron]

They had suggested i contact their local distributor - in my case, it was Nordic Audio of Sweden. I sent them an email about this, both to their "general" one, as well as their support / service department. That was over a month ago. They've yet to answer either one.