Problem of assembly?

I have a problem with a Shruthi. I completed the assembly. He saw the note from the midi, but we could not hear any sound, I made note of trial and began to play, but with a background noise. After shutting down does not play more, as soon as you turn you hear a noise that lasts 4 minutes and after the silence. I’m using is the current to 7.5 V.

Have you tried with another power supply (maybe larger voltage / current?)

I tried with another power supply, but no sound.
When the transformer and Out jack it clicks. Then, the filter works? The first time it worked I played a little bit to adjust the filter.
How can I play the top note.
And 'as if they were locked oscillators. The midi note always works.

I’m sorry, it’s very difficult for me to understand what works on your unit, what doesn’t, and what you have done so far.

I understand.
I’ve done more testing, you hear the sound, but very low, almost inaudible.
I checked the first power supply that I used and is not stabilized.
And 'You may have burned some component.