Chicken 64 returns with another repair video, this time focusing on a 1541-II floppy drive that produces strange and inconsistent error messages. On the surface, the drive powers up normally, but when attempting to read a directory, the output becomes corrupted. Instead of standard error strings, the system displays garbled or half-formed messages, making diagnosis tricky.
After opening the unit, attention turns to the CPU. Here lies the surprising discovery: the processor is running at 1.5 MHz instead of the correct 1.0 MHz. This unintentional overclocking is not an improvement. Instead, it throws off timing across the drive, explaining the erratic behavior. Occasionally the system powers up at the proper speed, which matches the times when error messages look normal.
Tracing the fault upstream reveals the cause. The CPU’s clock signal comes from the gate array, which itself divides input from the clock circuit. The incoming frequency, however, is too high. At 24 MHz instead of 16, dividing it produces the 1.5 MHz that confuses the drive. This points squarely at the clock circuit as the source of trouble.
The fix turns out to be simple. By probing inside the clock circuit, the frequency occasionally settles correctly, suggesting a capacitance issue. The clock section includes a variable capacitor, and after a small adjustment to C11 with a ceramic screwdriver, the frequency stabilizes at the proper 16 MHz input and 1.0 MHz CPU clock. Multiple power cycles confirm the correction.
With stability restored, the repair continues with standard maintenance: cleaning the read/write head, lubricating the rails, and verifying motor speed. Head alignment requires patience, but careful micro-adjustments bring every track into spec. Final tests show clean reads across the disk surface and a successful game load.
The video demonstrates how a puzzling set of errors on the 1541-II can come down to a misadjusted clock circuit. By spotting the unusual CPU frequency, the solution becomes clear and surprisingly quick to implement.
