Log of July 2006 events Wednesday, July 12, Wednesday, July 19
July 12
Meeting scheduled - 1:30 on Wednesday, July 12.
from Dave Bennet to: Jack Grogan, Dick Oswald, Ed Thelen, Pat Connolly, Al Hoagland, Joe FengPurpose of the meeting is to talk about overall system layout to incorporate the new servo system that Dick Oswald is designing, and to discuss how we should proceed. Wednesday, July 19
- Ed Thelen came in to do some measurements.
- Noticed the 733 differential amplifier (for amplifing the head read signal) has been removed.
A nice image of the plugs on the RAMAC
The resistance of the air valves is about 1700 ohms +- about 5% - The electromagnetic drive clutches have
- - about 310 ohms resistance,
- - and 1700 millihenries inductance.
The inductance was measured by a meter loaned to the 1401 project by Grant Saviers.- Pin outs of RAMAC Connectors shows no tachometer (pin 29) return wire -
- the black wire in the bundle goes to pin 24
- the blue wire in the bundle goes to pin 29
Pin 24 is listed as "Solenoid (3) H Common V + 40 V"- I am assuming pin 24 is a solenoid ground wire which the students connected to +40 volts for solenoid driving convenience? Could the actual solenoids in the original machine have had their other lead activated to +40 volts by say relays - and wire 24 have been the common solenoid and tachometer ground?
This is feasible as the tachometer has a high output (3.6 volts per 100 RPM), and any IR drop due to solenoid current (25 ma each, with no more than 3 solenoids energized at a time) would be insignificant.
- The top and bottom safety microswitches open when the arm assembly is too high or too low.
- I could not identify arm in/out limit switches - I need some expert guidance.
- I have updated Pin outs of RAMAC Connectors to better identify the labeling of the plugs at each end of the wire bundles, and to identify the sockets/plugs and pins interfacing the student driving board.
- Interesting fact - one revolution of the drive capstan (max 1000 RPM - 60 milliseconds) drives the head from all the way off disk - to innermost track -
If you have comments or suggestions, Send e-mail to Ed Thelen