RCF ART312A MKII amp help

[chirr]

I have 2 barely used RCF ART312As MKII, just took it out of storage and I noticed the mids/highs sound distorted on one.

I tried the mid from the other good speaker, sound distorted as well so it appears to be an amp problem.

The board says PST355E MKII

Also noticed some gunk on an SMD is this normal.

I have no experience repairing PCBs, anyone with experience want to point me in the right direction?

Thank you

[nickb]

It's probably just a little corrosion or contamination. Clean off using isopropyl alcohol. I doubt it's your problem. RCF aren't forthcoming with the schematics and if you have no experience this might be rather challenging.

If my memory serves me correctly, these use three Hypex class D power amp modules which are not serviceable, but you can swap them between the two speakers you have to see if one of those is the problem as they are the same.