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MDAC First Listen (part 00101101)

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John,
I'm getting "cracking" noise on the left channel of my modified MDAC - it's usually fixed by re-powering the unit, but happens about once a month (suddenly appears) - any idea what that could be? The noise is only heard when there's an audio signal (not silence) and it seems to be at signal level. I've checked both outputs (balanced / headphone) and it's happening on both.

It's not a major issue as it happens only rarely, but it may indicate something failing.

Any ideas?
Thanks.
 
Its the ESs Left Channel locking bug - do you have D3E enabled? (Keep it Enabled).
John - can you remind me: is there any cure for this? If I leave my m-dac powered on, it eventually makes white noise out of the left channel.
 
There is no cure as its an internal Bug in the ESS - only to keep D3E set to full suppression and also A,10 software has a different strategy to "work around" the issue so it may or may not be more effective in your system - but most critical is to keep D3E set to full suppression.
 
Even over USB? .. Yes, it's set to Full Suppression. Thanks for the info.

Yes, over USB and SDPIF - no difference (the ESS stil has to lock and sampling the input data).

The new ESS IC"s resolve the issue - but we would not face the issue in FDAC anyway.
 
What a horrid Day!

Its 6.25 am and I'm finally calling it a night and going to bed!

I manged to blow x5 USB hub IC's while trying to get the Detox USB section up and running - the problems started with badly soldered Surface mount IC's - which I then used a Circuit tester to probe the connections on each IC pin and the PCB to confirm connection, but unknown to me the Circuit tester I used was actually damaging the IC's!!!

I was chasing my tail trying to understand where the problem was - I resolded new IC's and use the circuit tester to confirm connection but then damaged the new IC's!

The HUB IC's are "leadless" packages - the pins are under the IC and thus hidden from visual inspection and to replace the damaged IC's the surrounding components also need to be removed - there are 28 connections from the IC to the PCB in a area smaller then my finger tip:-

https://dl.dropboxusercontent.com/u/86116171/Detox Damaged IC.JPG

You can see a damaged IC removed from the PCB and "flipped onto its back" and notice the tiny pads that solder to the board,,,, You can also see the other damaged Hub section with components / IC removed for waiting rework :(

By the time I realised what was happening I'd blown my stock of spare IC's so I'll have to order more... but once I understood what was going I had once IC remaining and was able to use this last device to confirm USB connection with the PC :) I'm too tired to do any further testing - but atleast the first Detox hub section works :)

With all the PCB rework (replacing the damaged IC and surrounding components) the poor old board looks a mess - but it is the first prototype...
 
What a horrid Day!

Its 6.25 am and I'm finally calling it a night and going to bed!

I manged to blow x5 USB hub IC's while trying to get the Detox USB section up and running - the problems started with badly soldered Surface mount IC's - which I then used a Circuit tester to probe the connections on each IC pin and the PCB to insure correct connection, but unknown to me the Circuit tested was actually blowing the IC's.

I was chasing my tail trying to understand where the problem was - I resolded new IC's and use the circuit tester to confirm connection only to damaged the new IC's!

The HUB IC's are "leadless" packages - the pins are under the IC and thus hidden from visual inspection and ro replace the IC, all the surrounding components also need to be removed - there are 28 connections from the IC to the PCB in a area smaller then my finger tip:-

https://dl.dropboxusercontent.com/u/86116171/Detox Damaged IC.JPG

You can see a damaged IC removed from the PCB and "flipped onto its back" and notice the tiny pads that solder to the board,,,, You can also see the other damaged Hub section with components / IC removed for waiting rework :(

By the time I realised what was happening I'd blown my stock of spare IC's so I'll have to order more... but once I understood what was going I had once IC left and was able to uses this last device to confirm USB connection with the PC :) I'm too tired to do any further test - but atleast the first Detox hub section works :)

With all the PC rework (replacing the damaged IC and surrounding components) the poor old board looks a mess - but it is the first prototype...

John, you deserve your sleep! What a hideous job. Fingerspitzengefühl doesn't come near to a description of what you need for it; if Fingernagelspitzengefühl is not yet a word, it should be......If it were anybody else I would say we all need a miracle , but I guess they are (almost!) routine for you. Keep it up!

Best wishes,
Bob
 
John I am just amazed you can work with such tiny parts it puts my my own clumsy skills into perspective .
 
What a horrid Day!

Its 6.25 am and I'm finally calling it a night and going to bed!

I manged to blow x5 USB hub IC's while trying to get the Detox USB section up and running -

Hi JohnW,

I think everyone is letting you off too easy on this one.

Firstly, I reckon after the third IC blew up, you should have known there is more wrong here than your soldering skills :). Look up Einstein's definition of insanity. :)

Secondly, what the hell you doing attempting such delicate task at 4:00+ O'clock in the morning? :)

Finally, you are probably living on crap English tea and Kit-Kat these days in the Lab. Get some decent sleep, get out and get some fresh air before you blow up any more stuff :)

Nevertheless, appreciate the hard work as always.

Hossein
 
Yes - I felt rather pixxed, stressed, worried, confused, upset etc etc...

Problem was I let Jarek mount the IC's as I have little experience with such fine pitch leadless devices... but lets say after yesterday (this mornings) epic battle I have now have more experience gained the hard way!

But "happily" went to bed after I manged to get one 'Hub" stage working with my last IC - meaning there is hope :) that lovely "double dong" chime from Windows as it Enumerates the USB Hub device - what a "happy" sound to finally hear at 6am...

As soon as I awoke I ordered more HUB IC's from Farnell today - they "should" be here by midweek...

Not often I make such a "mess" but lesson learnt the hard way about using the Huntron Tracker on toady's small geometry digital devices, and trusting someone else to mount your SMD devices!...

Until then back to tea and KitKat!!!
 
John, I'm sure there is film buried within that epic battle somewhere (if not a film about the whole MDAC2 / FDAC / VFET / Detox project?). Good work! I hope that you are enjoying the ride just a tiny bit!
 
John I am just amazed you can work with such tiny parts it puts my my own clumsy skills into perspective .

It gets harder as I age for sure - I'm not sure if its my eyes, the wavelength of the lamps in the Lab or the latest fad to laser etch the text on IC's but I find it really hard to read the device part numbers - and trying to solder "leadless" packages well the name says it all...

The constant drive to miniaturise components thanks to the phone industry...
 
It gets harder as I age for sure - I'm not sure if its my eyes, the wavelength of the lamps in the Lab or the latest fad to laser etch the text on IC's but I find it really hard to read the device part numbers - and trying to solder "leadless" packages well the name says it all...

The constant drive to miniaturise components thanks to the phone industry...

Sorry, John, its your age! Its the dreaded presbyopia catching up with you... trust me, I'm an optician!

You really need a nice headset binocular loupe to be working in stuff that small.
 
Sorry, John, its your age! Its the dreaded presbyopia catching up with you... trust me, I'm an optician!

You really need a nice headset binocular loupe to be working in stuff that small.

Quick search and I think your right :(

When I first get to the lab and work it takes time for my eye to focus "close in" - and especially "changing focus" to say look at the monitor further away...
 
Quick search and I think your right :(

When I first get to the lab and work it takes time for my eye to focus "close in" - and especially "changing focus" to say look at the monitor further away...

Yes, classic symptoms... possibly time to visit your local "Optika"?
 
Easily dealt with with spectacles or contact lenses, but no proven surgical method, and it would be difficult to imagine any surgical intervention that would work well, even in theory. The sort of acuity that you need for your job, I think best bet would be some spectacles with decent lenses.
 
Sorry, John, its your age! Its the dreaded presbyopia catching up with you... trust me, I'm an optician!

You really need a nice headset binocular loupe to be working in stuff that small.

Even my dentist and hygienist wear binocular loupes. I often wondered if a quality pair could be found that would not break the bank and I am not even working on anything as tiny as John.
 
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