Analogue-sequencer

--- In analogue-sequencer@yahoogroups.com, "Colinf" <colin@c...> 
wrote:
> You could bypass the backup controller temporarily to test whether 
it is the
> problem.
> Take it out the socket, and just jumper a wire from the +5v supply 
to the
> Vcc supplies on the RAM chips. This would be a wire from pin 1 to 
pin 8 of
> the DS1210 socket.

hm...this is kind of strange; i just tried this, and with the ds1210 
removed the response is the same as before, i.e. 'RAM TEST FAIL'on U2 
& U3, boot sequence, then ending in a top line saying 'tempo=149' and 
the usual bank/fts bottom line. with the ds1210 in place however, i 
get the 'RAM TEST FAIL' and boot sequence, but it ends in a screen 
saying '??/?? ??   PLAY' which looks like a much more normal response 
to a RAM test failure, with the '??'s referring to 'out of range' 
i.e. nonexistant or unreadable data.
i'm quite a bit more hopefull after this...
 
> If you still can't get it working, you can ship the main board to 
me and
> I'll check it out thoroughly on the scope/logic tester.

i guess i could do that but i'd much rather sort it out myself so i 
can try to learn a bit and understand what it is exactly that i'm 
doing..

> If all other ICs have been ruled out, it's possible there could be 
static or
> shock damage to one of the CPU lines.

is there a way to check this without a scope?

> Have you checked continuity of all the CPU, decoder, DS1210 and 
SRAM lines
> against the schematic, with the ICs removed ? Maybe there could be 
a broken
> track ?

i'll be doing this (again..) tonight. thanx again for the tips Colin.
grtz Chiel