After a fair amount of observation and experimentation, I soldered a 1M resistor and a 5000pf capacitor in parallel between pins 20 and 25 on the MCS-48 target socket. Problem solved. Programming happily away.
Hope that helps someone.
jml
Hi all there,
before trying this mod, i'd like to ask more info.
I have a Willem programmer and MCS48 adapter - an old toshiba with native Parallel port set on ECP on BIOS.
The willem is powered with 12V wall plug transformer.
I have set the jumpers J6 and J7 leaving the bottom contacts not connected (21V setup) and i've raised the variable resistor checking the first and the 20th pin (gnd) obtaining 21V on multimeter.
I have flagged on the box "1 -Vpp" in the "test HW tab" and a small green led on the adatper lights on.
Then i have tried to write the .bin onto a blank 8749H but the software gave me "error at 0x000001 Chip= 0x15 buffer = 0x35"
Must i do the mod to get the rig working?
There's a way to check that my adapter is Ok, more than the green led on adapter board?
My old Korg Poly61 will greet you if i'll keep him back to life.
Sorry for my newbieness, but i'm a musician, not a tech, i repair synth just as hobby.
Thanks,