Interesting drive failure

On 4/22/15 5:04 PM, David Gesswein wrote: Some SMD drives could microstep and some controllers implemented it. Not sure about yr drive or its controller. BTW, I did several searches for info on the Fujitsu drive without any luck. If u can get a utility to loop on reading a specific track and head then you can apply finger pressure to the top of the carriage to force the head slightly off track in either direction to see if it reads better in one direction or the other. Be careful with both pressure and location because if the servo decides it's lost it will probably do a recalibration which happens quickly and with force - could damage the finger. With an oscilloscope u can observe the raw head signal (differentially) and see if it increases in one direction or another. U can probably read single ended if u can figure out where is the output of the read preamplifier (might even be right next to the head stack). With a schematic, power supply and variable resistor u can inject an offset signal into the servo loop and move the heads off tract to the maximum head amplitude position. Again start low and slowly increase the injected signal. Tom