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BULLETIN NO. 232
64 MEMORY MAINTENANCE

2
64 MEMORY MAINTENANCE
ADJUSTMENT PROCEDURES

July, 1958

MILITARY PRODUCTS DMSION
INTERNATIONAL BUSINESS MACHINES CORPORATION

KINGSTON, NEW YORK IBM
r-
KINGSTON
I
The work reported in this document was performed under a ~
government contract. Information contained herein is of a TECHNICAL
proprietary nature. ALL INFORMATION CONTAINED PUBLICATIONS
HEREIN SHALL BE KEPT IN CONFIDENCE. No informa-
tion shall be divulged to persons other than IBM employees
authorized by the nature of their duties to receive such in- .
formation or individuals or organizations who are author-
ized in writing by the Department of Engineering or its ap-
. pointee to receive sucll information. GOVERNMENT RE-
LEASE MUST BE OBTAINED THROUGH THE CONTRACT
ADMINISTRATION DEPARTMENT BEFORE THIS INP'OR-
MATION MAY BE USED FOR COMMERCIAL APPLICA-
TIONS.
FOREWORD
The information contained herein supersedes the
related text on adjustment procedures in the Pre-
liminary Maintenance Data Book on Core Mem-
ory,andin T.O. 31P2-2FSQ7-142, dated April 1,
1957.

This bulletin is intended to be self-contained with
regard to adjustment procedures only. It in-
cludes the detailed adjustment procedures nec-
essary for properly setting up an oscilloscope,
for retuning the memory, and for ensuring that
the spare clock conforms to the memory timing
of the computer.

Where outside references are requ,ired, the read-
er is directed, in the text, to the applicable In-
struction Bulletin.
TABLE or CONTENTS
Heading Page
1. Tuning Procedure for X10 Oscilloscope Probe 1
2. Voltage Calibration of Tektronix Oscilloscope, Type 545 1
2.1 Calibration Equipment Requirements 1
2.2 Procedure 1
2.3 Function of Special Graticule (3033583) 4
3. Sweep Calibration of Tektronix Oscilloscope, Type 545 4
4. Core Memory Tuning Procedure 6
4.1 General 6
4.2 Pre-Tuneup Procedure 8
4.3 Tuning Procedure 8
4.3.1 Loading of Special Program 11
4.3.2 Check of Memory Timing (Clock) 11
4.3.3 Adjustment of DPD Currents 12
4.3.4 Adjustment of Read-Write Currents 14
4.3.5 PRF Test 16
4.3.6 Check of Sample Time 18
4.3.7 Balancing the Margins 18
5. Spare Clock Adjustments in Driver Panel Tester 20
5.1 Purpose 20
5.2 Procedure 20
5.2.1 General 20
5.2.2 Detailed Instructions 22

LIST OF ILLUSTRATIONS

Figure Title Page

1 Positive Calibration Waveform 3
2 Negative Calibration Waveform 5
3 Sweep Calibration Waveform 7
4 Core Memory Data Record Sheet (Earlier Type) 9
5 Core Memory Data Record Sheet (Current Type) 10
6 Inhibit and Drive Current Terminating Resistors 13

i
LIST OF ILLUSTRATIONS (cont'd)

Figure Title Page

7 Location of Drive Line Terminating Resistors 15
8 PRF Envelope 17
9 Sense Amplifier Output . 19
10 Clock Timing, Compute'r vs Driver Panel Tester 21

ii
ADJUSTMENT PROCEDURES

1~ TUNING PROCEDURE FOR X10 OSCILLOSCOPE PROBE

In order to make certain the oscilloscope probe does not produce distortion when
the oscilloscope is used for critical measurements, it is necessary to check and, if
needed, to adjust the linearity before making such measurements. The procedure for
tuning the prob~ is as follows:

1 .. Connect the probe to the CAL OUT output on the oscilloscope.

20 Set the VOLTS/CENT control at 0.. 05 and the SQUARE WAVE
GENERATOR for 2V ..

3. Set the oscilloscope SYNC control to INTERNAL, and adjust
the sweep until one complete cycle is displayed.

4. Using a small screwdriver, adjust the probe-adjusting screw
until the waveform displayed on the oscilloscope screen is a
perfect square wave"

5. If the probe adjustment cannot produce the display of a perfect
square wave, try adjusting another probe. If the display is still
unsatisfactory, try another oscilloscope.

20 VOLTAGE CALIBRATION OF TEKTRONIX OSCILLOSCOPE, TYPE 545

2.. 1 Calibration Equipment Requirements

To ensure that the oscilioscope will accurately measure the currents present when
tuning core memory, it should be equipped with graticule 3033583 and calibrated with
Oscilloscope Calibrator FR-112/FSQ (delay-line scope calibrator), Part No. 3204011.
The calibrator is adjusted to deliver a pulsed output of 2V amplitude.

2.2 Procedure

To calibrate the oscilloscope, proceed as follows:

Note

The calibrator must be placed on a level support
to ensure satisfactory operation of a mercury-
wetted relay contained in the unit.

1
1. Apply power to the of;cilloscope and the calibrator, and allow enough
time for the circuits to stabilize.

2. Set the PULSE AMPLITUDE control on the oscilloscope calibrator
to the value specified on the calibration chart. This sets the ampli-
tude of the output voltage ..

3. Set the OUTPUT PULSE SELECTOR to the + position ..

4. Rotate the VOLTAGE AMPLITUDE potentiometer until the meter
indicates the value specified on the calibration chart.

5. Rotate the VIBRATOR control in the clockwise direction until the
vibrator can be heard; then advance the control approximately 30
degrees beyond this point. This is a more reliable point for
vibrator operation. The calibrator output is now a 2V, 2 usec
pulse.

6. Check the d-c balance of the vertical amplifier in the oscilloscope
as follows:

a. Rotate the VARIABLE VOLTS/CM control back and forth,
and watch the trace for a vertical shift.

b. Slowly turn the DC BAL adjustment until the trace remains
steady while the VARIABLE VOLTS/CM control is rotated.

7. Using a tuned XIO probe, calibrated as described in paragraph 1,
connect the oscilloscope to the calibrator. Set the oscilloscope
controls to the following:

a. Set trigger slope to plus, INTERNAL.

b. Set the sweep control for 0.5 usec/cm.

c. Set the vertical voltage selector to O.05V/crn and the VARIABLE
control to the extreme clockwise position (CALffiRA TED).

d. Set the INPUT SELECTOR switch to the DC position.

Note

To avoid excessive parallax when observing wave-
forms, use a hood over the face of the oscilloscope
to accurately position the operator's head.

8. Display the pulse on the oscilloscope. Set the focus and intenSity
controls to obtain a clear, sharp trace. Set the astigmatism control
for an even trace. Use the vertical positioning control to place the
dot, which designates the start of a trace, so that the top of the dot
just touches the bottom centimeter scribe line. This establishes
the d-c ground level. (See fig. L)

2
TOP
I MILLIMETER
CENTIMETER
10 MA
SCRIBE LINE t
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9 0% -I- 90%,
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V ,,\'1
-I-
GRATICULE
3033583
--- -l-

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