MAINTENANCE INSTRUCTIONS
4.22 BLOWER MOTOR BELT TENSION ADJUSTMENT
Objective: To adjust tension of blower motor belt to approximately 114 inch (approximately 6 mm) of deflection. (See Figure 4-9.)
Equipment needed: Spring scale (0-1000 gm), 150 mm (6 inch) ruler.
Procedure:
a. Secure primary power to unit.
b. Remove rear access cover located Above primary input power connection.
c. Using a pencil, mark vertical position of drive belt midpoint.
SPRING SCALE
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AUJUSTMENT SCREWS
110-0191
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Figure 4-9. Blower Motor Belt Adjustment
d. Attach spring scale to drive belt midpoint and apply 1000 gm tension.
e. Again mark vertical position of drive belt midpoint.
f. Using the ruler, measure the distance between the two midpoint positions. Measurement should be approximately 1/4 inch (6 mm).
g. If deflection is incorrect,' loosen adjustment nuts and move blower to the right to increase basically mechanical problem can cause what appears to be an electronic malfunction and vice versa. In any case the problem should be thoroughly analyzed before adjustments are made.
Electronic troubleshooting is greatly facilitated by the modular construction: a new card may be substituted and the effect observed. Most difficult, of course, are subtle problems and those of an intermittent nature.
Visualizing solution (Magnasee) is useful under certain conditions for troubleshooting. At high densities the data cannot be satisfactorily resolved but such
d. Are the errors pattern related?
e. Do errors occur only on certain sets of
Model 9100 accepts and produces tapes conforming to the ANSI standards. Occasionally compatibility problems can arise:
a. Tapes written by and acceptable to the 9100 are not acceptable to another transport.
b. Foreign tapes cannot be read by the 9100 but its own tapes can be.
Three items may be involved: skew, speed, ramp times. These should be checked as described in the adjustment procedures.
4.23.3 OTHER MALFUNCTIONS
Normal trouble shooting procedures are involved in finding electronic malfunctions. The first things to check are the supply voltages:
+/-24 volts nominal unregulated will normally be about +/-26 volts under light load.
+/-10 volts +/-0.5 volt +5 volts +/-0.25 volt
Convenient test points for measuring supply voltages are: - Sensor Amplifier/Driver TPA - Sensor Amplifier/Driver TPB - Sensor Amplifier/Driver TPC
Observed: High error rate - clean machine. good tape Symptom
Continuous errors, every block (read mode)
Continuous errors, write mode only
Possible Cause
Broken connection to interface or internally
Bad preamp channel
Bad quad read amp channel Tape speed grossly wrong Bad head channel
Broken connection on write data or WDS lines
Bad write amp chanhel
Indication Action
Continuity Correct connection.
No output at test point on write Replace preamp.
test ~
No data at test point Replace quad read amplifier.
Visual or skewmaster
No output at preamp test point on write test
Continuity
No signal in write test mode
Adjust speed.
Replace head.
Correct connection.
Replace write amp.
Reference
4.16 4.23.5
~---+---~---~---,---~---P---~
Frequent write errors, few or no read errors
Write-read crosstalk
Frequent CRC, LRC errors, Wrong CRGgeneration in
no VRC errors interface
Read or write errors only at start of block
Read errors on long blocks only
Pattern related errors
Ramp time wrong
Tape path misaligned
Write-read crosstalk
Table 4-2.
Noisy signal at preamp test point
Wrong data at input
Read signals appear before ramp is complete
Tape bears heavily on one guide surface
Noisy signal at preamp test point
Troubleshooting
Check preamp gain.
Check face shield spacing.
Correct interface.
Adjust ramp time.
Mechanical alignment.
Check preamp gain.
Check face shield spacing.
4.19 4.21
4.17
4.9
4.19
Control Malfunctions Symptom Tape breakage or aborted load
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LOAD pushbutton activates servos when pressed but does not holdTape feeds forward after load point marker should be sensed and is rewound to physical end of tape
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No EOT signal
REWIND pushbutton inoperative
Rewind does not stop at LP but continues until tape is wound off reel
Reels rotate uncontrolled when power is turned on with tape in both vacuum
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Tape moves erratically, slips on capstan Capstan turns slowly when it should be stopped
Possible Cause Misadjusted reel servo(s) on Servo Preamplifier' module Broken tape signal clears LOAD flip-flop
a. Sensor Amplifier/Driver module b. Pushbutton Control module c. Photosensor (BKN) malfunction d. Sequencer module
e. Vacuum SWItch and/or vacuum blower
a. Marker strip miSSing from tape
b. Misadjustment of photosensor on Sensor Amplifier/Driver module
Same as load point above but for EOT
Logic malfunction, Pushbutton Control module, Sequence module a. Same as above
b. Photosensor adjustment wrong, Sensor Amplifier/Driver module
a. Servo preamplifier malfunction
b. Servo power amplifier (bad power tranSistors)
Head face shield touching tape Capstan zero adjustment, Servo Preamplifier module Table 4-3. Troubleshooting
Action Reference
Readjust. 4.11
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Replace module.
Replace module.
Replace sensor. 4.23.6
Replace module.
FIX.
Apply reflective strip.
Adjust photosensor e 4.15
4.15 Replace module.
Adjust photosensor. 4.15
Remove preamp. If reels stop, replace preamplifier
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module. Replace heatsink assembly or locate and replace bad power transistors.Adjust face shield setting. 4.21
Adjust for zero. 4.14
Voltages are measured to chassis (ground). Plus or minus 24 volts wUI increase to +/-32 volts when speed is greater than 150 ips.
NOTE
TURN POWER OFF WHEN REMOVING OR INSERTING CARDS.
If the voltages are not correct the trouble is either in the power supply or in the fact that the malfunction is loading' the supply excessively. Pulling cards from their sockets can help isolate an overloaded condition.. The power supply is short-circuit protected on the regulated voltages. Assuming the voltages are correct, Table 4-3 should help in isolating malfunctions.