[sdiy] Kawai mess

[>>>marjan<<<]

I haven't fried anything for a long time, but now I did it :(
My Kawai K1 rII rack went bannanas...
When I power it up all I get is blank lit display but no txt
on it. Display glows but nothing on it.

What happened: I've replaced one (working) opamp for better and
it worked OK. Then I tried to expand it's RAM. It has card slot
but I have no card so I traced the connections, got some info 
from list members too, and finally I was left with the scheme
where I could just piggyback RAM chip on exisitng one with /CS
pin routed to it's logic, all other pins soldered in parallel to
old one - it's OK, I've verified card connections few times.
You also need to pull up (or down) one line to tell the mpc
that you are using expansion card also. Seemed faultproof. 
Done that before on other synths, without a problem. Powered
it, intrnal banks worked ok, but when tried to access new ram
it showed error. But everything else worked OK. After half an hour
display went blank. Tried few resets but no change.

All board connectors are normal type _except_ display one, where
you insert ribbon type cable into double row of metal leafs
which squeeze each wire. Stupid design. I thought some of them 
got off or lose, or two wires touching, so I removed cable and
soldered it to bottom. Still, no cure. Measured ram battery
it's ok. Double checked all other connectors. Nothing

Sill haven't tried if it spits audio/midi. Next steps are
to desolder piggybacked ram, remove pullup, remove display
cable from the main board and try audio/midi.

Any suggestions? Have I fried display (seems classic backlit
two line type)? Or eprom/ram/the whole bloody thing?
Any suggestions are welcome. Help...


-- 



marjan


me    : Marjan Urekar
e-mail: urekar.m at eunet.yu
s-diy : http://surf.to/marjansystems
music : http://go.to/forcemajeure