Floppy won’t read
Step-by-step diagnosis for the Amiga 4000 rev 2 board. Each step lights up the signal or chip to measure in the explorer below.
The internal drive doesn’t spin, doesn’t move the head, or spins but won’t read. CIA-B gives the drive its orders and Paula receives the data.
- _SEL0Show on board →
Selecting the drive
_SEL0 selects the internal drive. When you insert a disk it must go low; if it never changes, follow it back to CIA-B.
- _MTRShow on board →
The motor
With the motor line low, the selected drive must spin. If the line goes low and the motor doesn’t turn, the problem is in the drive, not the board.
- _STEPShow on board →
The head
Each pulse on _STEP moves the head one track, and DIR picks the direction. If the head doesn’t move, follow these two lines to the drive connector.
- _TRK0Show on board →
Track zero
_TRK0 goes low when the head is on track 0. Kickstart uses it to park the head at the start before reading.
- _DKRDShow on board →
Read data
_DKRD carries the disk data to Paula. If the motor spins and the head moves but nothing arrives here, the head is dirty or the drive electronics are faulty.
Didn't fix it?
We repair these boards on our bench in Loures. The request already includes the board and the fault.
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