Either the DC/DC converter has failed or the opamp or some decoupling capacitor on the -15V. The measured resistance between pins 2-4 (-15V) is far too low. Since you already replaced the DC/DC converter I would guess the root cause is elsewhere.
That's helpful, thanks. So I take it that the cap you substituted isn't on the output of the DC-DC. Yet the DC-DC powers the OPA1612 and that opamp has local decoupling with a couple of SMD 'lytics as best as I can tell from your original pic. Which almost certainly takes the capacitance on the DC-DC output beyond the DS recommendation. How far beyond though I can't tell but it doesn't build confidence in the design when Mornsun's DS recommendations seem to be being ignored.
Now I made psu lm317/337, but not yet try to connect.
Disassemble dc-dc converter, power off, but the input and output pin are not isolated. pin 2 and 5 is 0ohm, pin 2 and 4 is 130ohm. 1-4 about 1300ohm (but it's not stable). 1-5 1000ohm. 1-6 infinite. If I connect external psu (+-15vdc), is it safe to pi under?
Thinking to buy new DAC.
Disassemble dc-dc converter, power off, but the input and output pin are not isolated. pin 2 and 5 is 0ohm, pin 2 and 4 is 130ohm. 1-4 about 1300ohm (but it's not stable). 1-5 1000ohm. 1-6 infinite. If I connect external psu (+-15vdc), is it safe to pi under?
Thinking to buy new DAC.
Attachments
Take a needle and unsolder-lift pin 4 and 8 of opamp and connect the dual power supply. If it is still hot than remove 2 smd ceramic capacitors near 3pins. I had some cases with damaged ceramic capacitors. If no voltage is on opa1612 than check if i see right there ar 2x4r7 resistors...they can be part of a Rc filter and can be burned, if opamp is defect
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hey, I m got idea to use es9038q2 as PC DAC, hence I need USB to i2s to send data from PC via USB/i2s to es9038q2m
as cheap as reasonable
so far I found this, quite popular on alie
https://pl.aliexpress.com/item/4001...etail.0.0.48af43ceeHZVeU&gatewayAdapt=glo2pol
will it work? any better at this price?
as cheap as reasonable
so far I found this, quite popular on alie
https://pl.aliexpress.com/item/4001...etail.0.0.48af43ceeHZVeU&gatewayAdapt=glo2pol
will it work? any better at this price?
A clone Amanero like that should work fine, but keep the wires between boards short.
I measured from grnd of DC jack, to pin 4 (or upper pad of failed cap) is 6 ohm; to lower pad of failed cap is less than 1 ohm. to pin 8 is about 16k ohm.
From dc-dc converter pin 4 to opa1612 pin 4, and converter pin 6 to opa1612 pin 8 are 6ohm.
I will try to remove failed cap and test again.
I found another failed cap which was near dc-dc converter. It's connected -15vdc to the grnd. After removed it, power on, the DAC working again.
Thank you very much for all of your support. I'm just IT guy without knowledge of electronic world but so happy to able to fixed it.
Thank you very much for all of your support. I'm just IT guy without knowledge of electronic world but so happy to able to fixed it.
Attachments
Following up with some more measurements. The OPA1656 is killer in the voltage follower position.
1K FFT: Almost 19 bits of usable range. Nuts I tell you, NUTS. For a cheap DAC anyway.
TD+N Vs Frequency: It measured beyond 20k where the filter wrecks it.
TD+N Vs Level:
Linearity: Not quite 16 bits of volume control without data loss.
RMS Voltage vs Frequency: I need to re-examine the high pass filter on the right channel. Guessing poor contact elevating the R and lifting frequency while dropping level.
Multitone:
IMD (MASSIVE ESS hump, but TD+N doesn;t seem to care):
1K FFT: Almost 19 bits of usable range. Nuts I tell you, NUTS. For a cheap DAC anyway.
TD+N Vs Frequency: It measured beyond 20k where the filter wrecks it.
TD+N Vs Level:
Linearity: Not quite 16 bits of volume control without data loss.
RMS Voltage vs Frequency: I need to re-examine the high pass filter on the right channel. Guessing poor contact elevating the R and lifting frequency while dropping level.
IMD (MASSIVE ESS hump, but TD+N doesn;t seem to care):
Hello everyone 
Here is a photo of my 'Rod Rain Audio DA10' DAC (dual ES9038Q2M) with its new OPAMPS ->
(other changes are also made)
I still haven't taken any measurements on this device because I don't have the instruments to do so.
I have tried many OPAMPS and these are what I find the most 'musical', that is my own opinion: this notion is purely subjective since there is no device capable of measuring the quality of musicality...
Here are some detailed photos of these OPAMPS and a brief technical sheet ->
Here is the link where you can get his OPAMPS ->
https://fr.aliexpress.com/item/1005..._main.298.41a85e5bptepBB&gatewayAdapt=glo2fra
Regards.
Here is a photo of my 'Rod Rain Audio DA10' DAC (dual ES9038Q2M) with its new OPAMPS ->
(other changes are also made)
I still haven't taken any measurements on this device because I don't have the instruments to do so.
I have tried many OPAMPS and these are what I find the most 'musical', that is my own opinion: this notion is purely subjective since there is no device capable of measuring the quality of musicality...
Here are some detailed photos of these OPAMPS and a brief technical sheet ->
Here is the link where you can get his OPAMPS ->
https://fr.aliexpress.com/item/1005..._main.298.41a85e5bptepBB&gatewayAdapt=glo2fra
Regards.
OMG, 230db of loop gain and so HUGE distortions -103db??Hello everyone
Here is a photo of my 'Rod Rain Audio DA10' DAC (dual ES9038Q2M) with its new OPAMPS ->
View attachment 1131175
(other changes are also made)
I still haven't taken any measurements on this device because I don't have the instruments to do so.
I have tried many OPAMPS and these are what I find the most 'musical', that is my own opinion: this notion is purely subjective since there is no device capable of measuring the quality of musicality...
Here are some detailed photos of these OPAMPS and a brief technical sheet ->
View attachment 1131176
View attachment 1131177
View attachment 1131178
View attachment 1131179
View attachment 1131180
View attachment 1131181
View attachment 1131182
Here is the link where you can get his OPAMPS ->
https://fr.aliexpress.com/item/1005..._main.298.41a85e5bptepBB&gatewayAdapt=glo2fra
Regards.
Did you notice that almost all resistors are E48? "Excellent CMRR" really?