DAC ES9038 Pro China Problems

[Sancho49]

Hi Everyone,

I've buy recently a China DAC ES9038Pro, but some problem with it.

___Description___
- 230V 50hz version
- PCB Version Rev. 1.3
- 2x NE5532 and 2x NE5534 Op
- DAC Chip ES9038Pro

_________Problems_________
1st Problem : When I play music, and stop it, some continous noise on speakers (Left or Right, or Left & Right side ... ) , noise like the wind ( Around 100 - 150hz )
The Noise level depand vary of the sample rate & bit rate of the music ... 44.1 > 352 / 16 > 32

- 44.1 very low noise on the speaker (Left or Right, alternatively & Random ... )

- 352Khz FLAC High Noise on the speaker ( Left and Right )

- 5.2Mhz DSD High Noise on the speaker ( Left and Right )

- No noise at the cold start. Dead silence

- The noise comes when i play music ( I Play a track just 1 second and directly stop ) , and the noise appears ...


2nd "Problem" : With the enclosure and GND Signal / Continuity between each !!!
With a multimeter : Continuity between RCA (Cold) and chassi !!!
I've fix the problem after remove a wire between chassi and the center 0V added under the board (Look Like a last minute fix ... )

Normal or abnormal connection ?
...

____ My Optimisation & Investivation ______

- Shield between RCore Transformer and DAC Board
- Twisted AC Wires
- Add IEC connexion ( Earth to Chassi)
- I've try different input, SPDIF and USB (Amanero card) with different computer and different player ( Audirvana / Jriver / Foobar ... ) different codec (ASIO / Wasapi ...) = same Problem

____Photos___

You have any idea ?

Thank You,

 

[Markw4]

First, you should put the ground wire back. It is supposed to be there for shielding and safety purposes.

The circuit board inside your dac is a common one that a number of people is the forum here use. Normally, the boards do not exhibit the symptoms you describe. Looks like the power transformers may be too close the circuit board. If a problem from that then noise you hear may be related to the mains frequency or a harmonic of that.

Otherwise, if you don't know how to troubleshoot or fix the device, your best choice may be to return it for a refund.

 

[Sancho49]

Thank You Markw4 for you're reply !
The ground / signal ground connection is strange on this dac ...

An externally hosted image should be here but it was not working when we last tested it.

On this schematic <--

Normal Ground / Signal Ground connection ?..

 

[Sancho49]

After some research ... The display is the problem !!!

I've upgraded the original LCD display to an OLED Display.
I think the "firmware" of the OLED Display is not compatible with ES9038PRO ... ( Filter selector / Sound Level ?!... )


With the original LCD display ... No noise, sweet music !


_____ Upgrade soon _____


- Add ferrites on the AC wires.

- Replacement of the FAKE Silmic II 47uF 35v with original
- Replacement of main power supply capacitors with Mundorff Mlytic AG.

- Replacement of OPAs 5532 & 5534 with AD797 & Muses 8920

 

[eljoantonyn]

@ Sancho49
How you came to know that the Elna Silmic on the PCB was fake ?
I'm curious as my DAC board have a lot of Silmic caps. May be its fake too......or not !

 

[Sancho49]

 

[eljoantonyn]

Interesting !


The Silmic branded caps in my DAC pcb are very colourful. One set of them is Yellow and the other set is Pink !
Weird ?

 

[Sancho49]

You have a picture of your DAC board ?

 

[Sancho49]

OPA Bypass with 100nF 50V X7R Type (Thank You Markw4 )

 

[eljoantonyn]

You have a picture of your DAC board ?

Yes, I do !

 

[Sancho49]

See the link below :

http://www.elna.co.jp/en/capacitor/pdf/catalog_19-20_e.pdf

The red capactior look like a "Cerafine" caps ... but not sure ...

 

[eljoantonyn]

I could find the red cap's reference in the data sheet.


BTW, data sheet which contains the description of the yellow colored cap.
http://www.paullinebarger.net/DS/Elna/ELNA 2004 Full.pdf

 

[phase]

Why put more ceramic bypasses on the op amp power rails when there are already the same value in that position already? Haven’t had anything good come from that before, and usually resonates.
Maybe mark meant to say across the rails? That would make more sense, but also depends on the op amp and whether it will respond well to that.

I would look at the analog filter, the pf value caps around the op amps. Those can be replaced with film/foil parts for a good benefit.

What page were the red/yellow caps on?

 

[eljoantonyn]

Regarding yellow and red silmics:

Red: Cerafine, For Audio series.
Yellow: Ultra miniaturized , standard series.

Refer page number 6 of the above linked PDF.

 

[phase]

So is that what yours are labeled?

Probably ok parts but wouldn’t be my first choice.

 

[Sancho49]

Hi Phase, thank you for you're reply !


If I understand, it's better to bypass 47uF Electrolytic capacitor with small value (MKP Capacitor?) ? Like this :

Exemple of bypass for the OPA AD797 :

 

[Sancho49]

Schematic of OPAs section :

 

[Sancho49]

Schematic of OPA Power Supply section :



I understand now ... A 0.1uF already exist in position C35 ...
The bypass tweak on last reply is useless ... ( in my opinion ... )

 

[eljoantonyn]

So is that what yours are labeled?

Probably ok parts but wouldn’t be my first choice.

I'll check again and report back in my thread !

 

[phase]

That’s what it appeared, that unless the different type of capacitor had a quality that works better somehow, it’s redundant or causing a resonance from the low esr of those parts along with the inductance of the traces on the board.
With the ad797 there, that does require a more specific arrangement for bypassing, as you have shown. There’s also a requirement for the feedback resistor having a small cap around it as well for stability. At least they are soldered in, that’s better than sockets for stability as well.


eljoantonyn; I should have replied before in the other thread as well.