SMSL D-6 troubleshooting (noise issues)

[ReDFoX]

Hi! My beloved D-6 became unusable after 3 years... It started making random noise sometimes and now I can hear that constantly.
Can someone guide me through troubleshooting?
I've checked 3V3, 1V, 4V, +-11V rails and they all seem fine (I haven't noted the voltage ripple tho). Can't really check 24M crystal since my cheap scope is only 250MS/s
The insides look clean, however, 10(?)uF cap in SMPS seems kinda bulgy...
I can attempt to monkey-repair it by swapping all electrolytic SMD caps, but I doubt that'll make a difference here

 

[AnalogSteph]

It started making random noise sometimes and now I can hear that constantly.

Access denied.

The insides look clean, however, 10(?)uF cap in SMPS seems kinda bulgy...

Where? I don't see anything. The apparent wetness around the feet of the 4700µ/10V ones is probably glue, they're mounted a bit awkwardly for some reason. Caps seem of decent quality if those Rubycons are any indication, so I wouldn't get my hopes up that it'll be this easy. If it's a cap, it's probably not one of the big boys. An ESR meter of sorts would be the most reliable tool for in-circuit testing. Tread carefully around the primary side (where the 22µ/400V is), check remaining voltage with a multimeter and keep a discharging resistor of 1-3.3 kOhms (1/2-2 W preferred) handy.

Or did you mean the small SMD ones marked "CE 10 HTZ" sans top vent? Looks like a 10µ of some description, but SMD electrolytic markings are a proprietary mess. I can't tell whether it has wet feet or not. In that position I'd think it's the startup cap anyhow, so you'd definitely notice if it were dead because the unit wouldn't even power up.

I would suggest measuring resistance across the two small SMD ceramics next to where it says +11V and -11V and comparing it.

So it's a noise in both channels? That would suggest either something severe on the analog supplies (did you check +/13 V near the DACs?) or an issue on DAC Vref. There is a 4 V rail? Hmm. That's an unusual value. I would think that the DACs would have a +5 V somewhere.

 

[ReDFoX]

Access denied.

Where? I don't see anything. The apparent wetness around the feet of the 4700µ/10V ones is probably glue, they're mounted a bit awkwardly for some reason. Caps seem of decent quality if those Rubycons are any indication, so I wouldn't get my hopes up that it'll be this easy. If it's a cap, it's probably not one of the big boys. An ESR meter of sorts would be the most reliable tool for in-circuit testing. Tread carefully around the primary side (where the 22µ/400V is), check remaining voltage with a multimeter and keep a discharging resistor of 1-3.3 kOhms (1/2-2 W preferred) handy.

Or did you mean the small SMD ones marked "CE 10 HTZ" sans top vent? Looks like a 10µ of some description, but SMD electrolytic markings are a proprietary mess. I can't tell whether it has wet feet or not. In that position I'd think it's the startup cap anyhow, so you'd definitely notice if it were dead because the unit wouldn't even power up.

I would suggest measuring resistance across the two small SMD ceramics next to where it says +11V and -11V and comparing it.

So it's a noise in both channels? That would suggest either something severe on the analog supplies (did you check +/13 V near the DACs?) or an issue on DAC Vref. There is a 4 V rail? Hmm. That's an unusual value. I would think that the DACs would have a +5 V somewhere.

Thank you for replying!
Sorry, I've messed sharing options( Opened file to everyone with the link

Or did you mean the small SMD ones marked "CE 10 HTZ" sans top vent?

Tbh, it looks slightly suspicious
This is a spectrum of noise (amplified):

I've checked voltages once again and they all seem fine. The voltage ripple is <100mV
1V:

4V: