PCC D3400 - Page 334

Table B-2
Troubleshooting Procedure Chart (Continued)
PROBLEM
PROBABLE CAUSE
RECOMMENDED REPAIR
15.
Emergency unload
1.
AC motor speed out ot
1-
Adjust AC motor speed control (refer to Paragraph 6.6 3.3 in manual).
caused by disk
tolerance.
speed error (atter
drive
is in Ready 2.
Detective Logic PCBA. 2. Check transducer output at U409-2 on Logic PCBA. If output is + 600 mv
mode)
or more, or -400 mv or more negative, and pulse train is not present at
TP24 (on Logic PCBA), replace Logic PCBA.
3.
Defective
Motor Control PCBA
3.
It pulse train Is present on TP24 (Logic PCBA), check pulse train at TP22
and/or Drive motor. (Servo PCBA). This should be 100Hz tor 50 Hz units and 120 Hz tor
60 Hz units. If observed pulses are correct, replace Motor Control PCBA.
It trouble persists, replace Drive Motor.
4.
Detective
Servo PCBA.
4. If observed pulses are not as stated above, replace Servo PCBA.
5.
Lower magnetic transducer
5.
If voltage at U409-2 (Logic PCBA) is within tolerance, check that lower
gap
out of tolerance.
magnetic transducer gap
Is within tolerance (refer to Paragraph 6.18.3).
If needed, set gap within tolerance according to Paragraph 6.18.3. If
gap cannot be set within tolerance, replace lower magnetic transducer.
6.
AC voltage output ot magnetic
6. Check if speed control adjustment is within tolerance (reter to Para-
pickup out ot tolerance. graph 6.6.3 In manual). Readjust speed control (R212) on Servo PCBA
according to Paragraph 6.6.3.3 it necessary.
7. Defective Logic
PCBA. 7. If speed control is within tolerance and the problem perSists, replace
Logic PCBA.
8.
Defective lower magnetic
8.
Check
it lower transducer gap is within tolerance (reter to Paragraph
transducer. 6.18.3 in manual). It transducer gap cannot be set within tolerance,
replace lower magnetic transducer.
16. Emergency unload
1.
Defective Logic
PCBA.
1.
Check
logic level at U327-5 (Logic PCBA). It low, replace Logic PCBA.
caused by Position
Transducer Lamp
2.
Detective Servo PCBA.
2.
Observe Position Transducer Lamp. If lamp is lit, replace Servo PCBA.
failure
3. Detective Position Transducer
3. It Position Transducer Lamp is not lit, check voltage on J203-10 (Servo
Lamp and / or detective Power
PCBA). If voltage Is within + 11.5v and -9.3v, replace transducer lamp.
Supply.
It voltage on J203-10 (Servo PCBA) is not within tolerance, reter to the
Recommended Repair
column, Problem 3.
17.
Disk tries to write
1.
Detective Read/Write PCBA
1.
If a low logic level exists at U306-12, check heads for shorts or opens.
through
two heads
or detective heads.
It heads are good, replace the Read/Write PCBA.
simultaneously