PX-201 only outputs very quiet aux output - even after amp board replaced.

Hi,

I have a Technics PX-201. I get no audible sound from the speakers and only a very quiet output over the aux output (that I need an external amp to even really hear).

I thought the issue was the amp board not delivering enough power, so I replaced it with an identical working board I got off of the internet. However this did not fix the issue, with the same quiet sound being output over aux.

I'm quite stumped as I know the amp is fine and I know the tone chip and ROMs are fine as the piano plays it's keys and demo recordings perfectly well.

Any ideas?

This is a repost as I think I posted it in the wrong spot first time round.