Stiction

OK, here are the actual procesdures from the manual : Check the DC volages at the control PCB J6 connector (to the read/write PCB) Pin J : +5V Pin E : -5V Pin 22 : +24V Pin B : +12V (If any of those are misisng/incorrect, there's a procedure to check them back through the actuator PCB, etc, but I think you can manage that...) OK, on to the test you need : Drive Not Ready. It assumes the power voltages are OK, and that the disk is rotating. Notes : 1) Ready indication will appea as a logical 1 on TP28 of the control PCB. 2) Ready will not become active for 1.5 minutes after AC and DC power are applied 3) The drive must be selected befroe Ready is available at the interface connector Test 1 : Check clock track amplitude at control PCB TP9 (must be more than 1.5V) Test 1 OK? No : Replace Read/Wrtie PCB [1] Test 1 OK ? No : Problem with clock head -- not field repairable Yes : go to test 2 Yes : Got to test 2 Test 2 : Check TP5 on control PCB for TTL level 500ns puleses every 2.2us Test 2 OK ? No : Replace control PCB [2] Yes : go to test 3 Test 3 : Check TP27 on control PCB for TTL level square wave of 70ns +/-5ns (14.2MHz) Test 3 OK ? No : Replace control PCB [3] Yes : go to test 4 Test 4 : Check TP26 of control PCB for a TTL level pulse 1.1us duration every 2oms (Index) Test 4 OK ? No : Replace control PCB [4] Yes : Test done ARD#'s notes [1] Check circuitry round 6B and 6D on the read/write PCB, these being the clock head amplifiers [2] Check round 2A and 1B(section b) on the control PCB. [3] This is the output of the phase-lock oscillator. Check Q3, 3D (oscillator), 2B, Q1, Q2 (phase detector), etc [4] Check counter 2E, register 1G, and associated gates -tony