I returned a perfectly working PS2 because the optical out wasn't working. After plugging in my replacement and still not getting any sound I found out the optical in on my Hi-Fi was dead 
I also blew the controller ports on 3 dreamcasts (2 were mine one was a friends) before realising a faulty vibration pack was at fault
I also blew the controller ports on 3 dreamcasts (2 were mine one was a friends) before realising a faulty vibration pack was at fault