CHAPTER 3 CHECKS AND ADJUSTMENTS
6. With a DVM, check all the regulated voltages b monitoring TPll, TP15, and TP18 with respect to TPl on
3.6 VACUUM AND AIR PRESSURE ADJUSTMENTS .1 System Vacuum Adjustment
Refer to Figure 3-5 and Table 3-4 while performing this adjustment.
1. Turn transport power on.
2. Mount and load a 267 mm (10-1/2 in) reel of tape.
3. Open the base assembly to access the rear.
4. Remove the red cap from the cripple reel measurement port and connect a differential air gauge with a range of 0 to 1016 mm (0 to 40 in) of water. Use the low pressure input of the air gauge to measure vacuum.
5. Place maintenance switch SI on the control M2 PCBA (Figure 3-6) toward the front of the transport to drive tape forward.
CRIPPLE REEL
~5~~UREMENT~O
°OCAPSTAN MOTOR
(A) VALVE ORIENTATION ON BASE ASSEMBLY (REAR VIEW)
o
N
(B) VACUUM VALVE DETAIL (C) PRESSURE VALVE DETAIL SHR-0170-84 MA-3488
Figure 3-5 Vacuum valve and Pressure Valve Te st Po ints
Table 3-4 Vacuum and Pressure Valve Components Figure 3-5
Reference Description
A System vacuum test point B Reel motor connections
C Butterfly valve adjustment screw D Take-up reel vacuum adjustment screw E Vacuum present switch
F Takeup reel vacuum port G Tape on reel switch
H Vacuum input (to pneunatic assembl y) I Butterfly valve lock nut
J Air bearing pressure adjustment screw K Pressure input (to pneumatic assembly) L Thread block pressure adjustment screw M Thread block pressure port
N Air bearing pressure port
NOT USED
TEST POINTS (1-24) J10 TO CONTROLS ASSEMBLY
oc::::J-O W 4 oc=l-O W5 oc::J-O W6 oc=l-O W7 oe::::J-O W8 oc:J.o W9 oc:::ro W10
TEST POINTS (25-48) Sl MAINTENANCE SWITCH
g
W12P8 TO INTERCONNECT D1 PC8A
W 13 o-c=J-<>
W14 O-C:J-o W15 o-c:JO W16 o-c:::J.<>
W17 o-c:::J.<>
W 18 o-c::J()
TEST POINTS (49-72)
Figure 3-6 Control M2 PCBA Adjustments and Test points
3-11
6. Observe the air gauge while tape is run;~ing forward.
Check for a system vacuum reading of 838 to 889 mm (33 to 35 in) of water.
7. If the reading is out of tolerance, loosen the butterfly valve lock nut (I) and turn the adjustment screw (C) for a r e a din g 0 f 8 64 mm ( 3 4 in) 0 f wa t e r. Wh i 1 e hoI din g the screw, tighten the locknut and observe the air gauge to make sure the adjustment has not changed.
8. Stop the tape and unload it. Remove the air gauge and replace the red cap.
9. Check the take-up reel vacuum as descr ibed in Pa ragraph 3.6.2.
3.6.2 Takeup Reel Vacuum Adjustment
Refer to Figure 3-5 and Table 3-4 while performing this adjustment.
1. Before starting this adjustment, make sure system vacuum is within the specified limits outlined in Paragraph 3.6.1.
2. Turn transport power off and remove tape from the supply reel.
3. Place disable servo swi tch S 1 on the reel servo PCBA (Figure 3-7) toward the rear of the transport.
4. Remove red cap from take-up reel vacuum port (F).
5. Connect a differential air gauge with a range of 0 to 1016 mm (0 to 40 in) of water to the take-up reel vacuum port. Use the low pressure input to the air gauge to measure vacuum.
6. Turn transport power back on.
7. Press and release the LOAD/REW button on the TU78 control panel.
8. Immediately rotate the take-up reel three full turns to deactivate the load fault zero function.
J12 TO INTERCONNECT 01 PCB A
Q---~
Q---~
24
TEST POINTS (1-24) TEST POINTS (49-72)
R76 REEL SERVO OFFSET ADJUST
R91 TAKE UP REEL LOAD SPEED ADJUST
Fig ure 3·-7 Reel Servo PCBA Adj ustments and Test Po ints
S1 REEL SERVO DISABLE SWITCH R52 SUPPLY REEL LOAD SPEED ADJUST
9. Observe air gauge and check for a reading between 508 mm ( 2 0 in) 0 f wa t e r, m a x i mum, and 45 7 mm ( 18 in) 0 f wa t e r , minimum.
CAUTION
The specified duty cycle for vacuum and air pressure solenoids is intermittent three minutes on and nine minutes off. Therefore, the uni t should not be held in this mode for over three minutes after which the coil should be allowed to cool for nine minutes.
10. If the read ing is out of tolerance, loosen the take-up reel vacuum adjustment screw (D) and slipe the friction plate forward or backward to obtain a reading of 483 mm
(19 in) of water.
3-13
11. Tighten screw while observing air gauge to make sure adjustment is not disturbed.
12. Press and release RESET button on the TU78 control panel.
13. Remove air gauge and replace red cap. Place reel servo disable switch Sl forward (servo enable position) •
NOTE
The two vacuum adjustments (Paragraphs 3.6.1 and 3.6.2) are interactive, and after performing one, the other should be rechecked.
3.6.3 Air Bearing Pressure Adjustment
Refer to Figure 3-5 and Table 3-4 while performing this adjustment.
1. Turn transport power on.
2. Mount and load a 267 mm (10-1/2 in) reel of tape.
3. Open base assembly to access the rear.
4. Remove red cap from air bearing pressure port (N) and connect a differential air gauge with a range of 0 -- 34 kilopascals (0 -- 5 psi). Use the high pressure input of the air gauge to measure pressure.
5. Place maintenance swi tch Sl on control M2 PCBA (Figure 3-6) toward the front of the transport to drive tape forward.
6. Observe the air gauge while tape is running foward and check for an air bearing pressure reading between 27.6 k i 10 pa s cal s ( 4 . 0 psi), m a x i m urn , and 2 4 k i 10 pa s cal s ( 3 • 5 psi) , min i mum •
7. If the read ing is out of tolerance, loosen the locknut and adjust the air bearing pressure adjustment screw (J) for a 25.8 kilopascals (3.75 psi) reading.
8. Tighten the locknut while observing the air gauge to make sure adjustment is not disturbed.
CAUTION
Excessive torque on the locknut damages port threads. Use extreme care.
9. Stop the tape, remove the air gauge, and replace red cap.
10. Unload the tape.
3.6.4 Thread Block and Cartridge Pressure Adjustment
Refer to Figure 3-5 and Table 3-4 while performing this adjustment.
NOTE
Both the thread block pressure and cartridge pressure must be adjusted at the same time since one ad j us tmen t directly affects the other.
1. Turn transport power off.
2. Place servo disable (Figure 3-7) toward disable pos i t ion) .
swi tch Sl on the rear of
the the
reel servo PCBA transport (servo 3. Remove the red cap from the thread block pressure port (M) and connect a differential air gauge with a range of o -- 1016 mm (0 -- 40 in) of water. Use the high input to the air gauge to measure pressure.
4. Turn transport power back on.
5. Press and release LOAD/REW on the TU78 control panel.
Immediately rotate the take-up reel six full turns by han d . Th i s de act i vat e s loa d fa u I t z e r 0 and c a use s the pressure solenoid to energize.
CAUTION
The specified duty cycle for vacuum and air pressure solenoids is intermi ttent three minutes on and nine minutes off. Therefore, the uni t should not be held in this mode for over three minutes, after which the coil should be
allowed to cool for nine minutes.
6. Observe air gauge and check for a reading between 660 mm ( 2 6 in) 0 f wa t e r, m a x i m um, and 5 59 mm ( 2 2 in) 0 f wa t e r , min imum.
7. If the reading is out of tolerance, loosen the locknut on the thread block pressure adjustment screw (L) and adjust the screw for 610 mm (24 in) of water. Tighten the locknut while observing air gauge to make sure adjustment is not disturbed.
CAUTION
Excessive torque on the locknut damages the port threads. Use extreme care.
8. Press and release RESET on the TU78 control panel.
3-15
9. Disconnect air gauge and replace red cap on the thread block pressure port.
10. On the front panel, remove the hex socket head screw from the cartridge pressure port in the lower cartridge restraint (Figure 3-8), and install the tube fitting (PN 29-23228) .
11. Connect the differential air gauge with a range of 0 --1016 mm (0 -- 40 in) of water, to the tube fitting using the high input to the gauge.
12. Press and release LOAD/REW on the TU78 control panel.
Immediately rotate the take-up reel six full turns by han d . Th i s de act i vat e s loa d fa u 1 t z e r 0 and c a use s the pressure solenoid to energize.
CAUTION
The specified duty cycle for vacuum and ai r pressure solenoids is intermi ttent three minutes on and nine minutes off. Therefore, the unit should not be held in this mode for over three minutes, after which the coil should be
allowed to cool for nine minutes.
13. Observe the air gauge and check for a reading between 76 mm (3 in) of water, maximum, and 50.8 mm (2 in) of water, min imum.
MA-3484 SH R-0173-84
Fig ure 3 --8 Cartridge Pressure Check Point
14. with no cartridge if the reading is out of tolerance, adjust the cartridge pressure adjustment screw (Figure 3-5) for a reading of 63.5 mm (2.5 in) of water.
15. Check cartridge pressure with tape and cartridge loaded.
The pressure with a cartridge should be greater than 229 mm (9 in) of water.
16. Press and release RESET on the TU78 control panel.
17. Disconnect air gauge, remove tube fitting and replace socket-head screw.
18. Steps 3 through 16 may have to be repeated several times to ensure adjustment integration. Observe all cautions.
19.
NOTE
An alternate method to the preceding steps would be to acquire two differential air gauges. Connect both gauges to the respective ports, and make adjustments while observing both gauges.
Place the servo disable swi tch PCBA, toward the front of the posi tion) .
Sl, on transport
the reel servo (servo enable 3.7 CAPSTAN SERVO ADJUSTMENTS
The following are procedures for adjusting the capstan speed, start ramp, and forward and reverse stop ramps. Capstan speed adj ustment affects tape speed as it moves past the read/wr i te heads. Start ramp adjustment affects the amount of time it takes for the capstan servo to accelerate the tape from the rest position to full data handling velocity (125 in/s). stop ramp adj ustments affect the amount of time it takes for the capstan servo to decelerate the tape from full data handling velocity to rest posi tion. You must perform the adjustments in the sequence given.
1. Verify power supply voltages according to Paragraph 3.3.
2. Place both STI ports off-line by placing the PORT SELECT A and B buttons on the TS78 control panel in the disable
(out) position.
3. Set the transport rotary switch in the number 1, 2, or 3 position (maintenance mode) •
4. Load any write-enabled 267 mm (10.5 in) tape on the desired transport. Place the transport on-line.
3-17
5. Plug an RS232-compatible, external terminal -- a handheld termi na 1 (HHT) for examp1 e -- into the EI A connector on the TS78 control panel (Figure 2-25). For terminals that require +5 V power, +5 V (at lA maximum) is available at a 3-pin Mate-N-Lok connector on the panel.
6. Turn the external terminal on.
7. Type CTRL C on the terminal keyboard. Repeat the entry until TA78> appears.
8. To check capstan speed, type RUN VELOCITY/UNIT=X where X is the desired transport cable number: 0, 1, 2, or 3. (If X=0, you may omi t "/UNIT=X" from the command.) The tape drive runs the capstan speed check routine on transport X and displays a message on the external terminal.
9. A displayed message of OK indicates the capstan velocity is within specifications. If this is the case, proceed to s t e p 1 3 . If cap s t. a n vel 0 cit y r eq u ire s a d jus tm e nt, the tape drive runs the routine repeatedly and the displayed message is similar to the one shown below.
Velocity test: R47 CAPSTAN SERVO 0
*
Th e " * " i nd i cat e s t h e ide a 1 val u e. Th e "0" i n d i cat e s t he actual value and can be on either side of the asterisk.
10. To adjust capstan velocity, adjust potentiometer R47 on the capstan/regulator PCBA (Figure 3-2) while observing the display, until the "a" and
"*"
merge. If the "0" is on the left of the "*", the capstan speed is too low and R47 must be turned clockwise. If the"a"
is on the right of the "*", the capstan speed is too high and R47 must be turned counterclockwise.NOTE
If EOT is detected, the tape dr i ve rewinds the tape and contines to repeat the test routine. Do not adjust R47 during the rewind operation.
11. Press and release CTRL C to exit from the test. The tape drive displays TA78>.
12. Type RUN VELOCITY/UNIT=X where X is defined as in step 8.
The displayed message should be OK.
13. If you suspect an intermittent capstan speed problem, type RUN VELOCITY/UNIT=X/LOOP where X is defined as in step 8. The tape drive then runs the capstan speed check routine repeatedly on transport X. The displayed message is similar to the error message in step 9. Observe the display for about 30 seconds noting any irregularities.
Then press and release CTRL C to exit from the test.
NOTE
An alternate procedure for measuring capstan speed is to measure the frequency of the tach pulses. Connect a scope to control M2 PCBA, TP40 (Figure 3-6). The time period from trailing edge to trailing edge should be 80 +0.8 us.
14. If it was necessary to adjust capstan speed, then the PE gains must be adjusted (Paragraph 3.10.3).
15. To check the start ramp, type RUN RAMP/UNIT=X where X is defined as in step 8. This tests the start ramp as the capstan velocity was tested in step 8.
16. If the displayed message is OK, no adjustment is required and you can proceed to step 20. Otherwise, the start ramp requi res adj ustment. The rout ine is run repea tedly and the displayed message is similar to the one shown below.
start ramp: R59 CAPSTAN SERVO 0
*
The
"*"
and "a" indicate the ideal and actual values asdescribed in step 9.
17. To adjust the start ramp, adjust potentiometer R59 on the capstan/regula tor PCBA (Figure 3- 2) whi Ie observ ing the display, until the "a" and
"*"
merge. If the "a" is on the left of the "*", the capstan speed is ramping up too slowly and R59 must be turned clockwise. If the"a"
is on the right of the "*", the capstan speed is ramping up too quickly and R59 must be turned counterclockwise.18. Press and release CTRL C to exit from the test.
19. Type RUN RAMP/UNIT=X where X is defined as in step 8. The displayed message should be OK.
20. If you suspect an intermittent start ramp problem, type RUN RAMP/UNIT=X/LOOP where X is defined as in step 8. The start ramp routine is then run repeatedly and the displayed output is similar to the error message in step 16. For 30 seconds, observe the display for irregularities and then use CTRL C to exit the test.
3-19
NOTE
The following is an alternate procedure for measuring the start ramp.
• Rewind the tape and place the transport on-line.
• Create a 3200 FCI pattern on the tape by executing a WRTMAI command through the ASCII port in keypad mode. (Both STI ports must be off-line.) Rewind the tape.
• Connect an oscilloscope to the TU78.
vertical CHI to GCR/PE preamp 1 PCBA R14 top lead (Figure 3-9)
• Connect a jumper between the control M2 PCBA TP30 and TP25.
• Set control M2 PCBA maintenance switch Sl to the front (toward you).
The tape alternately starts and stops.
• Refer to Figure 3-10a for a representative scope waveform and settings.
•
The start ramp rise time (0 to 95 percent) should be in the 1.1 to 1.3 ms range.•
If it is out of adjustment, adjust capstan/regulator PCBA R59 for 1.2 ms.•
Return control M2 PCBA Sl to the center position.• Although there is no adjustment, you may want to look at the reverse start ramp profile. The start ramp may measure from 1. 1 to 1. 3 ms except there may be a small "forward hitch"
envelope for a 1.7 ms duration preceding the ramp. This forward hitch envelope is normal if there has been no tape motion for about 10 to 20 ms or more before a reverse motion command. Refer to Figure 3-10b for a representa t i ve scope waveform and settings.
READ HEAD
SLIGHT OVERSHOOT HERE IS DESIRABLE
PROBE:
(SHOWING FORWARD HITCH) MI\-7306
SHR-017~}-84
Figure 3-10 Forward Start Ramp
3-21
21. To check the forward stop ramp, type RUN FWDSTOP/UNIT=X where X is defined as in step 8.
22. If the displayed message is OK, no adjustment is required and you can proceed to step 26. Otherwi se, the forward stop ramp requires adjustment. The routine is run repeatedly and the displayed message is similar to the one shown below.
Fwd stop ramp: R66 CAPSTAN SERVO
* o
Th e "
* "
and " 0" i n d i cat e the ide a 1 and act u a 1 val ue s a s described in step 9.23. To adjust the forward stop ramp, adjust potentiometer R66 on the capstan/regulator PCBA (Figure 3-2) while observ ing the display, unt i 1 the "0" and
"*"
merge. If the "0" is on the left of the"*",
the capstan speed is ramping down too slowly and R66 must be turned clockwise.If the "0" is on the right of the "*", the capstan speed is ramping down too quickly and R66 must be turned counterclockwise.
24. Press and release CTRL C to exit the test.
25. Type RUN FWDSTOP/UNIT=X. The displayed message should be OK.
26. If you suspect an intermittent forward stop ramp problem, type RUN FWDSTOP/UNIT=X/LOOP. The forward stop ramp routine is then run repeatedly and the displayed output is similar to the error message in step 22. For 30 seconds, observe the display for irregularities and then use CTRL C to exit the test.
NOTE
The following is an alternate procedure for measuring the forward stop ramp.
• Rewind the tape and place the transport on-line.
• Create a 3200 FCI pattern on the tape by executing a WRTMAI command through the ASCII port in keypad mode. (Both STI ports must be off-line.) Rewind the tape.
• Connect an oscilloscope to the TU78.
Vertical CHI to GCR/PE preamp 1 PCBA R14 top lead (Figure 3-9), external sync to control M2 PCBA TP2l (Figure 3-6)
• Connect a jumper between the control M2 PCBA TP3~ and TP25.
•
•
Set control M2 PCBA switch Sl to the front The tape alternately stops.
maintenance (toward you).
starts and
Refer to Figure
representa t i ve scope settings.
3-11 for waveform
a and
• The forward stop ramp fall time (1~~
to 5 percent) should be in the 1. ~2
to 1.13 ms range.
•
If it is out of capstan/regulator ms.adjustment, adjust PCBA R66 for 1. ~8
• Return control M2 PCBA Sl to the center position.
a. CORRECT WAVEFORM
PROBE: X10 HORIZ: 0.2 MSEC!DIV VERT: 50mV/DIV CH1: PREAMP R14 SYNC: AC EXT NEGATIVE
TP21 CONTROL M2 PCBA NOTES: 1. STOP
RAMP IS MEASURED BETWEEN 100% AND 5%
2. ADJUST THE FALL TIME FOR NO OVERSHOOT OVERSHOOT
b. INCORRECT WAVE FORM SHOWING OVERSHOOT
Figure 3 11 stop Ramp
3-23
MA·7305 SHR-0176·84
27. To check the reverse stop ramp, type RUN REVSTOP/UNIT=X where X is defined as in step 8.
28. If the displayed message is OK, no adjustment is required and you may proceed to step 32. Otherwise, the reverse stop ramp requires adjustment. The routine is run repeatedly and the displayed message is similar to the one shown below.
Rev stop ramp: R78 CAPSTAN SERVO
* o
rrh e "
* "
and " 0" i n d i cat e the ide a 1 and act u a 1 val ue s a s described in step 9.29. To adjust the reverse stop ramp, adjust potentiometer R78 on the capstan/regulator PCBA (Figure 3-2) while observing the display, until the "0" and
"*"
merge. Ifthe "0" is on the left side of the "*", the capstan speed
is ramping down too slowly and R78 must be turned clockwise. If the "0" is on the right of the
"*",
the capstan speed is ramping down too quickly and R78 must be turned counterclockwise.30. Press and release CTRL C to exit from the test.
31. Type RUN REVSTOP/UNIT=X. The displayed message should be OK.
32. If you suspect an intermittent reverse stop ramp problem, type RUN REVSTOP/UNIT=X/LOOP. The reverse stop ramp routine is then run repeatedly and the display is similar to the error message in step 28. For 30 seconds, observe the display for irregularities and then use CTRL C to exit the test.
NOTE
The following is an alternate procedure for measuring the reverse stop ramp.
• Rewind the tape and place the transport on-line.
• Create a 3200 FCI pattern on the tape by executing a WRTMAI command through the ASCII port in keypad mode. (Both STI ports must be off-line.) Rewind the tape.
• Connect an oscilloscope to the TU78.
Vertical CHI to GCR/PE preamp 1 PCBA R14 top lead (Figure 3-9), external sync to control M2 PCBA TP2l (Figure 3-6)
• Connect a jumper between the control M2 PCBA TP30 and TP25.
• Set control M2 PCBA maintenance switch Sl to the rear (away from you). The tape alternately starts and stops.
• Refer to Figure 3-11 for a
• Refer to Figure 3-11 for a