Write Protect Switch Adjustment; Read/Write Test - HP 9130K Service Manual

5-12
Maintenance
Figure 5-10. Index to Burst Waveform
Write Protect Switch Adjustment
The disc drive head assembly may be severely damaged while performing this adjustment.
For this reason, replacement or adjustment of this switch is not to be done in the field.
Read/Write Test
A read/write test may be performed to verify proper operation of the read/write circuitry on
the 9130K drive. Perform the following steps in the order shown:
1. Connect the equipment as shown in Figure 5-3.
2. Insert a test disc (not the alignment disc) into the drive and close the latch.
3. Connect and setup the oscilloscope as follows:
Connect channel A to TP4/E4 (READ DATA) and ground lead to TP6/E11.
Connect channel B to TP7/E7 (INDEX) and ground lead to TP10/E11.
Trigger:
Display:
Volts/DIV:
Time/DIV:
Internal on channel a (POS)
Channel B
.05V/DIV (using 10: 1 probe)
5/-1s/DIV
4. Apply power and depress and release the DRIVE VALIDATE, MOTOR ON and
WRITE IF & 2F WRITE ENABLE pushbuttons ON the DSU.
5. Depress and release the DWRITE IF pushbutton and observe the oscilloscope dis-
play. The presentation should be like that of Figure 5-11. If the waveform is distorted
or if point A and point B overlap, there is a problem in the read or write circuit.
6. Depress and release the WRITE 2F pushbutton and again observe the scope display.
The presentation should be like that of Figure 5-12. Waveform distortion indicates
read/write circuit failure.