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Old 27th February 2012, 09:40 AM   #291
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Hi guys.

I'll do some surgery on the board.

1. First of all. Is there a layout of that board available to the public??

2. On a first visual examination I noticed two empty pads.

R3 is missing (close to the Torx).
C70 is missing (close to the STA320).

If HifiMeDiy is still following this thread, please let me know if that is an issue.

3. What I'll do next

a. getting rid of the relais
b. and plugging my Wuerth coils in. I'll put them underneath the board.
Somehow I don't want to have those coils sitting right next to the
surrounding resistors, elcos etc.
c. let see


Cheers

Last edited by soundcheck; 27th February 2012 at 09:43 AM.
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Old 1st March 2012, 07:40 AM   #292
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Hi, it's normal for R3 and C70 (un-soldered).
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Old 1st March 2012, 09:25 AM   #293
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Thx Hifimediy. I guessed that.


Progress Report:

Stage 1:

I applied some tweaks. Relays removal, Würth coils ( mounted underneath the board), better chip decoupling.

Folks. 100% success. The sound was really nice at this stage. The noise went down
considerably.

I've been enjoying that modification level for exactly one day...

...when I decided to apply further mods that I still had in mind and were recommended by a friend of mine..


Stage 2:

1. replaced the 3.3.V with a low noise type -- with a temporary separate power-on switch.
2. removed the woofer relay and coils -- and left the outputs open!?!?!?! ( open output -- problem??)
3. Some more decoupling

THAT ONE FAILED!!!!!!!!!!!!!!! Noooo, I can't believe it.

After applying those final little tweaks everything seemed to come up again -- all voltages were there, LEDs on, PIC seemed to work...

...BUT ---- NO SOUND.

Folks that's driving me crazy. Two days ago I had a great performing amp in my
hands and 10 hours later I screwed it. Damned.

I've been looking for almost a day after the problem. All voltages seems to be OK. I also
put everything the way it was the last time it worked. Still no sound.
I'm running out of ideas.

I guess without a scope it'll be difficult to trace the issue down.


PLEASE: If anybody has an idea of what can go wrong or what and how to verify.
Please let me know.

@HIFIMEDIY: How far are you with your redesign/new batch of that amp.
I'd reorder immediately a new one. In case there'd be no progress on your side: What would be the minimum number of units that would justify producing a small
new batch of the old design.


Just some more comments:

Improvement proposals for rev 2 of the board, that you might consider:
(I'm not a real HW expert. So please apologize and/or correct me if I'm wrong or misinterpret things.)

While scanning the design for quite some hours now, some potential areas of improvement I'd like to bring up over here:

1. All digital and analog 3.3V pins sit on one rail. No ferrite beds or similar - just a little
decoupling.
We're talking about the STM controller, the SPDIF receiver, the clock, the PIC, the
control unit. With just a little extra effort this situation might be improved.
Though you're the experts.
(However . It is IMO still amazing how this unit performs -- after the tweaks.)
2. The PIC with its internal clock sits right beside the one and only 3.3V regulator.
I'd put some space in between and I'd also hook it up to a nicely isolated supply.
3. I don't think that the output stage is well done. All those coils and relays in close
interaction with buffer caps for the main amp power rail, etc. Design should be
more careful here. I do understand the space constraints due to the chosen
heatsink. Still, you shouldn't place those sensitive parts in such a noisy high-power
HF environment.
4. I'd love to get all the AC related stuff removed from the board. I'm sure a single pole
24 DC voltage supply would be widely accepted and maybe even preferred.
Production cost can be lowered resp. those budgets can be put on better 3.3V supply.
5. It would be nice for us tweakers to have mount points for external DC supplies, that
would replace onboard supplies easily. (Twisted Pear audio is doing this very nicely on the Buffalo DACs)

THX

Cheers
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Old 2nd March 2012, 01:37 PM   #294
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Hi folks.

I don't give up on it. My device is still not singing.

I measured some pins at the STA320 while data are delivered from the source. It seems to stay quiet.

DDX1A/B = 0V ( seem to be kept low)
DDX2A/B = 0V

RESET= 3.3V
EAPD=0,9
TRI_STAE=3,3
OCDETECT=3,3
FAULT=3,3
TWARN=3,3


Can anybody confirm above values to be OK??? What would I have to check next??



BTW: The 5V reg, is it only used as 3,3V pre-regulator. If yes. Could it be removed in case I'm using an external 3.3V supply??


Thx for your support.

Cheers
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Old 4th March 2012, 11:49 AM   #295
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Hi,
RESET= 3.3V
EAPD=0,9
TRI_STAE=3,3
OCDETECT=3,3
FAULT=3,3
TWARN=3,3
These levels seem ok.
And 5V is not used for other device except a LED (for power).

DDX1A/B = 0V
DDX2A/B = 0V
Means no audio signal output from sta320, so may be you have to check the I2S signal from CS8416 to sta320 first.
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Old 4th March 2012, 02:07 PM   #296
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Quote:
Originally Posted by hifimediy View Post
Hi,
RESET= 3.3V
EAPD=0,9
TRI_STAE=3,3
OCDETECT=3,3
FAULT=3,3
TWARN=3,3
These levels seem ok.
And 5V is not used for other device except a LED (for power).

DDX1A/B = 0V
DDX2A/B = 0V
Means no audio signal output from sta320, so may be you have to check the I2S signal from CS8416 to sta320 first.

THX for the feedback. Step by step I'm hopefully getting there.

I'll try first to check the I2S bus with a voltmeter. Should be sufficiant to see if anything is ongoing.


I'll get a scope next week. That'll be much better.


Cheers
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Old 4th March 2012, 04:36 PM   #297
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I2S checkup:

1.6V on bit and word clock

on the data I measure 0.8 when
playback is started.

The signal seems to arrive at the 320.

Looks good I guess.
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Old 4th March 2012, 05:00 PM   #298
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Hi there.

Just a stupid question -- as I said I do not have any background in HW design.

Why is the thermal pad of the 3,3V regulator connected to the positive 3.3.V rail on
the board?

I'd expected a ground connection.

Anyhow. I had my friend check his setting. It's the same over there. It doesn't seem to be a problem at least.

Cheers

Last edited by soundcheck; 4th March 2012 at 05:04 PM.
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Old 10th March 2012, 02:01 PM   #299
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Quote:
Originally Posted by soundcheck View Post
I2S checkup:

1.6V on bit and word clock

on the data I measure 0.8 when
playback is started.

The signal seems to arrive at the 320.

Looks good I guess.
A multimeter is useless for digital signal I think.

Quote:
Originally Posted by soundcheck View Post
Hi there.

Just a stupid question -- as I said I do not have any background in HW design.

Why is the thermal pad of the 3,3V regulator connected to the positive 3.3.V rail on
the board?

I'd expected a ground connection.

Anyhow. I had my friend check his setting. It's the same over there. It doesn't seem to be a problem at least.

Cheers
It's normal, it's 1117-3.3 regulator has output on the thermal pad, just like LM317.
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Old 10th March 2012, 02:30 PM   #300
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Quote:
Originally Posted by hifimediy View Post
A multimeter is useless for digital signal I think.

No. I don't think it's useless. I can clearly see if and when the playback is started. The data line level goes up on the voltage as soon as I press play.

Obviously I can't verify what kind of data in what shape are delivered.

My scope just arrived. My troubleshooting options should slightly improve
soon.


Cheers
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