[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.


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.


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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