> The ready lamp flashes not when the servo burst is >visible, but when the heads are just before it. > Why? Well, I probably set the gain too high on the read/write module.
Hello, I'm sure you read the manual, however I add some explanation to be sure. The best head position is not where a servo track is at maximum amplitude (head is exactly centered to a servo track), but where you read two servo tracks with the same amplitude (so head is exactly between two servo tracks, in middle position). Comparative measurement of two servo tracks allow the servo control to understand the position of the head in respect to data track. If the best position for data track is not where servo have same amplitude probably the head is misaligned or the spring support of the head bent / deformed. To analyze head circuits you need a good oscilloscope, you should be able to see burst of servo tracks and data tracks too, with two channels you can understand if analog to digital threshold / pulses signal conversions do work as expected. Time ago I fixed an RL02 having a malfunctioning head amplifier circuit. The gain was too low. When I increased it rotating variable resistor, the circuit begun to ring (barely auto-oscillate), so was nearly unstable. Data and servo signals were corrupted, but this was visible only zooming on oscilloscope after careful trigger alignment. I don't remember exactly what I did, but some capacitors needed replacement, then I tuned head gain while loading a platter to the best position for operation, maybe slightly lower than manual recommendations. Then it worked perfectly. Andrea
