help with Weilang power

[prezden]

I have a Weilang dac that has been sitting on the shelf for a few years and decided to use it. Not sure if I have the proper ps though. The ps is 12/12ac. The dac requires 8-12ac and 15ac so it’s not exact. The dac led’s shows power and usb on but there is no sound at all. The computer recognizes the dac. Any suggestions please.

 

[surfstu]

I'm guessing here, and I'm far from an expert. But it may be that the USB is powered by the 8-12Vac and this sounds like it is working as the computer recoqnises it as a soundcard.

The 15Vac is probably to power the opamps and if the onboard regulators require 15Vac they may not deliver any voltage if you are only feeding them 12Vac.

Do you not have any other way of supplying 15Vac to test?

Stu

 

[prezden]

thanks Stu- That’s kind of what I thought, although I thought the 12Vac would have done something. Maybe I will have to buy a different power supply.

 

[surfstu]

If you have a Digital Volt Meter, you could rule out the PSU issue

 

[prezden]

The voyage measures at V12ac and V12ac. I guess that 12 is not enough for the regulators. I would not have thought that 3V would have made that much difference.

 

[prezden]

how hard would it be to boost the 12Vac to 15Vac

 

[phase]

Most are either 12-0-12, or 15-0-15, 9, and 9.
Dual supply for analog output stage, dac chip digital, and dac chip analog(along with the receiver chip perhaps).
I see three terminal blocks there, think you will likely need some additional transformers.

 

[surfstu]

Yes, I can see 3 sets of diodes for AC rectification, and, as phase has said - there is also an extra terminal block that is not connected in your photo.

I would look up the standard pins for opamps, one or more will be ground, one will +Vdc and one will be -Vdc. Then you can check to see if you have DC voltage at the pins of the 2 opamps, middle top of your photo. I expect if you have DC there then they will probably work.

You could then try and parrallel your 12vac so that all terminal blocks have 12vac. I am unsure that this is safe and will not do damage to the board though so please maybe wait to see if another member thinks this is a good idea!

I expect that the worst that could happen is that the regulators get hot, but it may be ok to test,
Stu