[sdiy] CZ-1000 update and memory mod help

Joe Frey frey at radioles.com
Tue Mar 10 05:31:28 CET 2020


Hello all, To those that answered my original post asking for guidance I 
found the problem. The output relay had gone bad and needed to be replaced.

So, after getting the synth to sound good again I decided to make an 
improvement and add ram power management so my custom patches wouldn't 
disappear when I put the synth in it's case for half a year. It turns 
out there's a chap that made a mod that I found out about that people 
say works. I contacted him and though he no longer provides the kit he 
did supply the info to make that mod.

https://www.artefacts.nl/bitsandpieces.html

He also gave this advice, "_Before you start modifying the CZ you should 
check if you can change the standby voltage as described in the 
installation manual_. You should also check the RAM chips get a voltage 
between 4.8Volt and 5.2Volt when the unit is switched on. If you can not 
get these voltages within range the kit will not work."

Of course being me, I ignored the first line of the instruction and made 
and installed the mod. DOH! Now, everything is cozy and in place but I 
can't use the trimmer to get the standby voltage down to 3.2V. I can get 
it to 3.7V. I am wondering if I put a diode in the end of the VBR 
regulator circuit to use the diode drop and try and  get from 3.7 to 3.2V?

The schematic is found here.

https://www.synthxl.com/wp-content/uploads/2018/01/Casio-CZ1000-schematics.pdf

And the VBR power supply is at page 4, grid 4F. And, the ribbon cable 
pin I am measuring voltage at is pin 9.

Any advice is appreciated. JoeF.



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