[sdiy] Future SYNTH-DIY/breadboard

[Rainer Buchty]

>   Well certainly not customized ASICs and PGAs and the like, but sure, 
>you can definately fix a newer machine.  I had a local person bring me 
>a Yamaha PSS-something or another [...] I traced the front panel wiring 
>back to the main CPU board and found two buss buffer chips.  74244s in 
>SSOP form.  Fixable?  Definately.  Got it working in no time and 
>charged a heck of a lot less than what the local Yamaha shop wanted to 
>even LOOK at the machine.

Yes, such cases exist -- luckily, the designers *did* (or had to) rely 
on external buffers instead of implementing them into the ASIC.  And 
luckily, it's often enough these little glue thingies which die.

But what if some other, not so easy to replace component died? Doesn't 
need to be some ASIC, even a mask-programmed microcontroller can be the 
"killer" which ultimately ruins the machine.

>Of course not all modern repairs will be that easy... but to call 
>everything new not fixable.  Not true.

>From my Ensoniq experience, I have mostly died panel processors 
(mask-programmed 6500/11), dead keyboard scanners (mask-programmed 
6500/11), or dead CEM3379. Other defects, like dried out capacitors or 
similar are rather seldom.

Ok, that might be a specific design problem, since those problems mostly 
occur with the ESQ1 but not its almost identical sibling SQ80... But 
still...

Rainer