[sdiy] CZ-1000 update and memory mod help

[MTG]

Wow, that (original) circuit is insane. Hopefully someone on this list 
can understand all of it because I sure can't.

On 3/9/2020 9:31 PM, Joe Frey wrote:
> 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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