Tu bym szukał, zresztą coś jest w opisie, na tej stronie ze schematem,
On some Z70833 ISSUE1 boards R45 is omitted and the inverted clock signal created by IC15a (present at CKEXT on the edge connector) is inverted again by IC15f and routed to the CPU clock input. This is achieved with factory fitted patch wires. This modification also includes a 330pF capacitor between the input of IC15a and 0v.
This change to the clock was integrated into the Z70833 ISSUE2 pcb. The clock signal output from pin 87 of the gate array (IC1) is no longer connected to the R45 component position which is still present but is shorted out by a component trace on the top side of the board. No R45 component is fitted. (The R45 position is removed completely on the ISSUE 4 motherboard). The capacitor mentioned above is given the designation C53, but is not fitted to all ISSUE2 boards.
Dlatego w NANO siedzi ls123 który sygnał CLK doprowadza do ładu bo co płyta ZX to było to inaczej robione, i dlatego dałem ten jumper do CLK.