It should be possible to run the Jupiter ACE at 6.25 MHz speed (Double Ace normal speed)
Parts: Z80C00010PEC a 10MHz Z80A cpu.
Cut Ace pcb here
1.] You need to cut this track or remove both components at one end from the PCB to
disconnect the B-counter output from the CPU clock generator.
2.] Then you have to solder a wire from the A-counter input (Z9 pin 1) to the components
after the cut. Then Ace will run at 6.5 MHz
Next, you will need to replace the Z80 CPU with the faster one, the Z80C00010PEC.