Old Skool Service
So, after milking the internet dry and coming up empty handed, I wrote to Yamaha (yes, I put pen to paper in this day and age!).
A week later nice chap call Steve from the AV department posted me a colour photocopy of the manual. Now that's service!
Here it is if anyone would like it:
https://www.dropbox.com/s/20fdsblajz27ug2/YP-511YAMAHAUserManual-EN.pdf?dl=0
no body seem to have the C4 svc mnl
Brutal I forgot to ask you what soldering iron do you use 45W or 25W and what tip to use as I am just learning and would like to start soldering and getting used to the timing to remove the iron without making a mess etc! Thanks!There's also http://sportsbil.com/yamaha/
http://audio-heritage.jp/YAMAHA/
A very useful site, with Google translation.
Here I found that one big difference between Ns 500 and Ns500M is woofer diameter. Ns500M has 30cm (12") woofer and Ns500 has 25cm (10") woofer diameter.
Some English sites said it has the same woofer dimension.