Generates master timing signals required by your modular video synthesizer.
Cadet I Sync Generator (C1) generates the master timing signals required for your modular video synthesizer in both NTSC and PAL formats. C1 includes a 14-pin video sync output header which transmits timing information to other modules, such as Cadet II RGB Encoder, or Cadet IV Ramp Generator. It can also synchronize its timing, and consequently that of your entire video synthesizer, to an external video source.
The sync generator is literally the heart of the Cadet system. It provides NTSC/PAL timing signals on a 14-pin header for use by other modules such as the Cadet II RGB Encoder, Cadet IV Ramp Generator and the Cadet IX Voltage Controlled Oscillator. It can also sync to an external source via the RCA jacks on the front panel. More in-depth information is in the Cadet I Sync Generator’s Owner’s Manual.
The component that helps keep time along with the ATMEGA88 is the Citizen Finedevice CSX750VCB13.500M-UT Voltage Controlled Crystal Oscillator. Sadly it is at this point obsolete and difficult to come by, if not impossible. Some sort of modification is needed to update this module for 2025. There’s a lot of good information about possible directions in this LZX Community thread:
[Project] Sync Generator modification
Given that discussion, I feel like Bastien’s (@syntonie) 27MHz crystal with a flip flop to divide by two to get 13.5MHz is the path of least resistance for now. This was suggested in December of 2022. In fact, a board , VIDCLK13M5-REVA, was added to the LZX Cadet GitHub repository 5 months ago that is an intended fix?
Looking at the BOM, The 27MHz crystal is a CTS 357LB3I027M0000. The options for this VCXO are:
After looking closer at the datasheet, output is enabled if pin 2 is NC:
The thing I don’t understand is where this might be added to the sync generator PCB.
