Hi A2bur,
Some checks on what mentioned:
- ”Powerlinks tested with working speakers” – Does that mean that when connected via Powerlink, all speakers do switch from Stand-by/Off to On?
- If they work with Powerlink, is your issue of not switching to On, with the RCA/Line input?
What you mention about sponge, probably is about the foam: fallen apart and sticking to PCB’s and components. If so, this is a common problem and you will have to clean everything out.
This foam rot can cause shorts or even eat away parts of the copper traces.
can you share pictures of this?