Thank you, alamakazam.
I don't think there are engineers and electricians in Sony Singapore. They send items to Malaysia to get repaired. When I brought broken Walkman to repair, Sony service center told me that, and he found the walkman was Japanese version (manufactured in Malaysia) and said, "You need to go to Sony Japan." And my Discman D22 is made in Japan. I don't think even Sony Japan can fix it. They are irresponsible about more than 10 years old product. But I know there are shops or persons who can fix just adjusting some Variable Resistors.
