Casio CZ/ VZ/ FZ - Pro Series

On Sat, Jul 16, 2016 at 09:34:05AM +0900, Daniel Forr\ufffd danforcz@... [CZsynth] wrote:
> I don't think this can be caused by CMOS chips.
> 
> Bigger problems with long time sleeping instruments can be caused by  
> old capacitors, mainly electrolytic ones.
> 

That's really only in old valve equipment, a combination of 1950s manufacturing technology and very high voltages used.

> Repeating switching on/off can't help so much, important on it is the  
> phase when machine is on. Because it was enough time off :-)

Yup

> So what can help is to leave the machine on for longer time, but to  
> watch it (danger of the fire!).

Definitely keep an eye on it.

> And the best is to check all caps and maybe change electrolytic caps  
> looking suspiciously in PSU (or elsewhere in the circuits).

Worth looking at, but don't just replace parts for the fun of it.  If you suspect a capacitor is genuinely faulty, change it.  I've done maybe a dozen faulty electrolytics in things that weren't cheap shitty switched-mode power supplies in nearly 30 years.

> When PSU delivers stable voltages properly on spec, it's time to check  
> all the other things - first all connectors and chips in sockets, as  
> this is where oxidation can cause bad contact. Clean, de-oxit, reseat  
> more times...

Correct wall-wart is a biggie.  Get one with about 9V, the correct polarity, and about 1A output.
I think the CZ "stock" one is rated for about 750mA or so, but more current is better (within reason - you don't want to be dragging a welding genset to gigs).

> If this all doesn't help to revive the machine, it's necessary to do  
> other checking and  diagnostics, and maybe replace more components.
> 
> Problems can be also solved by changing RAM backup battery (and  
> leaving the machine without battery for 24 hours), by factory reset,  
> by loading good set of sounds, and of course by using the machine (for  
> example problematic microswitches can return  to normal operation when  
> used for some time - something like self-cleaning).
> 
> Just my experience from reviving of many old machines. It's not rocket  
> science.
> 
> Daniel Forro

A lot of synths have some sort of factory reset button that will clear any RAM patches, and (more importantly) nuke anything that's in RAM that might be corrupt and affecting the operation of the instrument.  More complex instruments (particularly digitally-controlled analogue synths like the Ensoniq ESQ-1/SQ-80 hold calibration data in RAM for the filters) keep stuff around in RAM and behave very strangely if it's corrupt but not corrupt enough to force it to reinitialise everything.

IIRC the CZ1000 has a reset button on the bottom you're meant to poke after changing batteries.

-- 
Gordonjcp MM0YEQ