Sound Problem, with sega mega drive model 1

[konio38]

Hi there i got a sega mega drive model 1 at a good price, i hook it up, and the image was fine, but the sound was very low, and the headphone jack didnt worked, so i have decided to make the AV mod, and i made 2 options, i have at first tried to connect the sound by the headphone zone, and i hadnt any sound, then i used the mono sound from the AV cable zone, and i had the same problem as originaly had, very low sound, so i came here asking for help, what could this problem be, i just dont get how i can have sound but with so low intensity, by the way the chip sound is the yamaha YM2612, and the encoder chip is the SONY CXA1034P.

thx in advance.

[konio38]

Sorry about the doble post but i have read that i could get the sound directly from the sound chip, can that solve my problem? How do i do it?, once again thank you for your time.