READ DECODE CIRCUIT ADJUSTMENTS

Read decode test and adjustment procedures for 2200 bpi models (Read/Write Assembly No. 108141) are contained in Paragraphs 6.12.1 through 6.12.3; all test points are located on the Read/Write PCBA unless otherwise specified.

NOTE

The oscilloscope time base must be calibrated either via exterior calibration device or using the 10 MHz oscillator on the Logic PCBA.

6.12.1 RPN PULSEWIDTH ADJUSTMENT 6.12.1.1 Test Configuration

(1) Remove the interface connector and Terminator PCBA from connector J101 and J102 on the Logic PCBA.

(2) Connect a disk exerciser having read/write capability to J101 or J102 on the Logic PCBA.

(3) Apply power to the drive. Observe that the READY indicator is illuminated; allow a 5-minute warmup period.

(4) Write an all-zeros pattern via the disk exerciser.

(5) Connect oscilloscope Channel 1 probe to TP9. Connect the test probe ground clip to ground reference TP1.

(6) Position sweep trace 1 division below centerline of graticule.

(7) Set oscilloscope Channel 1 sensitivity to 1v per division.

(8) Set sync to internal, normal mode.

(9) Set oscilloscope to trigger on the positive slope of RPN.

(10) Set oscilloscope sweep to 0.1 JAsec per division.

6.12.1.2 Test Proced u re

(1) Establish test configuration described in Paragraph 6.12.1.1.

(2) Observe RPN waveform on oscilloscope Channel 1 (TP9) as shown in Figure 6-19.

(3) Adjust oscilloscope so that the leading edge of the RPN coincides with the center graticule line.

(4) Press the X10 MAG switch on oscilloscope to display 10 nsec per division.

(5) Measure RPN pulsewidth at the 1v level on oscilloscope centerline.

TP9

~,--~,,---::

RPN

~---~~

TP10~

i '

I _ _ OL.

/ - OV

I I

1

I

/,---~\. ^-3V

I K,---lV

TPll

I '

^{I ' ov}

~oo~ I I

PATIERN I

I

I

ONES WINDOW I

i4-1-- - -ADJUSTED - - - I - I

!

^INTERVAL

I

³³⁷¹

Figure 6-19. Read Pulse Narrow/lOnes' Window

116E

(6) Acceptable limits:

D 1500 rpm

• 50 nsec (minimum)

• 60 nsec (maximum) D 2400 rpm

• 40 nsec (minimum)

• 50 nsec (maximum) 6.12.1.3 Adjustment Procedure

When the acceptable limits are exceeded, the following adjustment is performed.

(1) Establish test configuration detailed in Paragraph 6.12.1.1.

(2) Adjust R69 on the Read/Write PCBA to 55 nsec (for 1500 rpm) or 45 nsec (for 2400 rpm).

6.12.2 'ONES' WINDOW SETTING 6.12.2.1 Test Configuration

(1) Remove the interface connector and Terminator PCBA from connector J101 on the Logic PCBA.

(2) Connect a disk exerciser having read/write capability to J101 on the Logic PCBA.

(3) Apply power to the exerciser and the drive. Observe that the READY indicator is illuminated; allow a 5-minute warmup period.

(4) Write an all-zeros pattern via the disk exerciser.

(5) Connect oscilloscope Channel 1 probe to TP10. Connect the test probe ground clip to ground reference TP1.

(6) Position sweep trace 1 division below centerline of graticule.

(7) Set oscilloscope Channel 1 sensitivity to 1v per division.

(8) Set sync to internal, normal mode, on Channel 1, and trigger on the negative slope.

(9) Set oscilloscope to trigger on the positive slope of RPN.

(10) Connect osci lIoscope Channel 2 probe to TP11. Connect the test probe ground clip to ground reference TP1.

(11) Position sweep trace 1 cm below centerline of graticule.

(12) Set oscilloscope Channel 2 sensitivity to 1v per division.

6.12.2.2 Test and Adjustment Procedure (Long)

(1) Observe 'ones' window on oscilloscope Channel 2 (TP11) as shown in Figure 6-19.

(2) Measure the time between the leading edge of RPN TP10 to trailing edge of 'ones' window TP11.

(3) If the pulsewidth is not within adjusted tolerance listed in Table 6-5, adjust R83 for the specified value.

6.12.2.3 Test and Adjustment Procedure (Short) (1) Write all-ones pattern via the disk exerciser.

(2) Observe 'ones' window on oscilloscope Channel 2 (TP11) as shown in Figure 6-19.

(3) Measure the time between the leading edge of RPN TP10 to trailing edge of 'ones' window (TP11).

(4) If the pulsewidth is not within adjustment tolerance listed in Table 6-5, adjust R79 for the specified vaiue.

6-38

Table 6-5

RPN 'Ones' Window Pulsewidth Values

Adjustment

Speed Zeros Ones Tolerance

1500 rpm 485 nsec 445 nsec ± 8 nsec 2400 rpm

I

^{300 nsec}

I

^{270 nsec ± 5 nsec}

6.12.3 DATA AND CLOCK PULSEWIDTH ADJUSTMENT 6.12.3.1 Test Configuration

(1) Remove the interface connector and terminator PCBA from connector J101 and J102 on the Logic PCBA.

(2) Connect a disk exerciser having read/write capability to J101 on the Logic PCBA.

(3) Apply power to the exerciser and the drive. Observe that the READY indicator is illuminated; allow a 5-minute warmup period.

(4) Write an all-ones pattern via the disk exerciser.

(5) Connect oscilloscope Channel 1 probe to TP12 (Read Clock). Connect the test probe ground clip to ground reference TP1.

(6) Position sweep trace 1 cm below centerline of graticule.

(7) Set oscilloscope Channel 1 sensitivity to 1v per division.

(8) Set sync to internal, normal mode.

(9) Set oscilloscope to trigger on the negative slope of Channel 1.

(10) Connect oscilloscope Channel 2 probe to read data TP13. Connect the test probe ground clip to ground reference TP1.

(11) Position sweep trace 1 division below centerline of graticule.

(12) Set oscilloscope Channel 2 sensitivity to 1v per division.

6.12.3.2 Test Procedure

(1) Observe Read Data TP13 (and Read Clock TP12) on oscilloscope Channels 1 and 2, respectively, as shown in Figure 6-20.

(2) Measure and note the pulsewidth.

(3) Acceptable limits:

D 1500 rpm

• 130 nsec (minimum)

• 170 nsec (maximum) D 2400 rpm

• 100 nsec (minimum)

• 120 nsec (maximum) 6.12.3.3 Adjustment Procedure

When the acceptable limits are exceeded, the following adjustment is performed.

(1) Establish test configuration detailed in Paragraph 6.12.3.1.

(2) Adjust R86 (Read Data TP13) or R82 (Read Clock TP12) for the correct timing within the acceptable limits.

116E

2.0V (READ

DATA, TP13) - - - _

1.OV - - - - - - - \

f-- - - -

- - l . O V

OV - - - - ~-. ^{_ _ _ -J.} ~---OV

I I

f.-PULSE WIDTH--.j

Figure 6-20. Read Clock/ Read Data Pulsewidth 6.12.4 SQUARING AMPLIFIER (U2) BALANCE ADJUSTMENT 6.12.4.1 Test Configuration

(1) Disconnect P310 on Read/Write PCBA.

(2) Connect DVM (2v dc range) between TP4 and TP5 on the Read/Write PCBA.

(3) Apply power to the drive.

6.12.4.2 Test Procedure

(1) Measure dc voltage differential between TP4 and TP5.

(2) Acceptable limits:

• O.Ov

+

0.01v (maximum)

• O.Ov - 0.01v (minimum) 6.12.4.3 Adjustment Procedure

(1) Adjust R59 to zero volts between TP4 and TP5.

(2) Reconnect P310 on the Read/Write PCBA.

6.13 TEMPERATURE COMPENSATION

The following paragraphs describe test configurations and test procedures for the Temperature Compensation PCBA. There are no adjustments for this PCBA.

6.13.1 TEMPERATURE COMPENSATION TESTS

The Temperature Compensation PCBA operates in conjunction with two thermistors mounted in the area of the removable disk and fixed disk(s). Thus, a signal is provided which is proportional to the temperature difference between the two temperature monitored areas and offsets the heads accordingly.

NOTE

All test points referred to in Paragraph 6.13 are located on the Temperature Compensation PCBA unless otherwise specified.

6.13.1.1 Test Configuration

(1) Prepare the drive to receive a disk cartridge as detailed in Paragraph 3.3.

(2) Insert the test disk cartridge.

(3) Operate the drive in the Ready mode for a minimum of 15 minutes.

6.13.1.2 Test Proced u re

(1) Using a digital voltmeter, connect the positive lead to TP and the common test lead to TP8 (ground).

(2) Acceptable limits:

• +

0.1v (maximum)

• - 0.1v (minimum)

6-40

(3) If the acceptable limits of the voltage at TP2 are not met, continue to (4) below.

(4) Place a temperature probe between the upper two heads adjacent to the head-lift tower and allow 1 minute for temperature stabilization.

NOTE

Temperature measuring equipment should have a range from 20°C to 31°C (68°F to 87.8°F) with an error limit not greater than + 0.5 °C (+ 1°F).

(5) Using the digital voltmeter, move the positive lead to TP4 and keep the common test lead at TP8 (ground).

(6) Monitor the voltage on TP4 and note the reading on the temperature probe.

(7) Use the temperature probe reading to determine the RP4 voltage value graphed in Table 6-6.

(8) Acceptable limits are indicated for each temperature probe reading in Table 6-6.

(9) Repeat Steps (5) through (8) using TP1 instead of TP4.

(10) If the test point voltage is not within acceptable limits, begin troubleshooting techniques with U1 or U3 and work backwards to U2.

Table 6-6

Output from Thermistors TP1 and TP4 Versus Temperature

VOLTAGE

/

/

1

(ACCEPTABLE UPPER LIMIT ~ V i

/V

^{i / /}

2.5 I--l-!! -+---!-+-!--+-N---::O--M~I N~AL--V~A:-'"""LU:::-E t---t-=!! /?--+-i -+-V-r-t--t-, -/fr/-t--1

! : !

i'---4 ' /

ⁱ

Y

I I ! i

J// ' Y //

I

AT TIP1 2.4 I---T--+----+--+--+--t--~t--!-/+-I ---r--+---t---:,4--t-1 -t-~___j

OR TIP4 ^{I' / ' ,/ I'}

V i/_+---t--_+---f---1

i / , y '

~

^{I I}

, / I " I ' I 1

2.3 1---+---/----,/1~-VI--: -rt--,!' --;---///i'----t-I----:A+:::-CC:;;:::E~PT"';-:AB::-:LE:-;-L~OW-;-;;E:;;-R -:-;-LlM;-;-;I:;:-1T

/ , / ,---r-

^I

//1

/i ^'/~

^I

==ttl

^{I I}

2.2 I---+--+/-r---+/---r--- ), ( i , ' t

-I / /1 , : '

I / / ' ! ,

// /!

^{~-~7----r- i i i t}

-2.1 I--+----,L/~,

/--b',

~+--', _/_-;-"/~+---i-__ ~~-+I -+-, -+---t--T

1

___j

/ " I ' I

v<; T ^{:!I : I}

2.0 V

L ) /' ~I

^-t---I

-+----+--o+----! : - - '

-r---;---: ~: ^.

1.9, )/

r/ _i

j !

1.8 i

20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35+-Co 68 69.8 71.6 73.4 75.1 77 78.8 80.6 82.4 d4.2 86 87.8 89.6 91.4 9 3 . 2 ' - -fO

TEMPERATURE PROBE READING

3244

116E

Dans le document MODEL D3400 DUAL- AND QUAD-DISK DRIVES (Page 183-188)