IBM System/360 2050 User Manual

Connector Installation
1. Remove upper and lower drive connectors by
removing the mounting screws. Check alignment of
bit plane connector tabs with tabs on terminating
resistor card at top and the drive card on bottom.
Resistor card and lower drive card may be shifted
for horizontal alignment by loosening the two hold-
down screws in each resistor card.
2. Reinstall connectors and tighten the mounting
screws.
3. Load upper and lower drive connectors by
turning spring- loading screws clockwise until they
bottom. Do not over-tighten.
STORAGE PROTECT (SP) SERVICE CHECKS
Storage protect timing information is located in
Volume 1 of the ALD's, Page AAOOO.
Reference Voltage and Sense Level Adjustments
Two potentiometers set the storage protect refer-
ence and sense level voltages. The card at
02B-A3J4 has a 1000-ohm potentiometer (bottom) for
the reference voltage and a 2000-ohm potentiometer
(top) for the sense level voltage adjustments.
Reference Voltage
Reference voltage should be set as follows:
1. Connect an accurate de meter between
02B-A3J4Dll (+ lead) and any B06 pin (- lead at
-3 volt reference).
2. Using the bottom potentiometer at 02B-AJJ4,
adjust for a potential difference of +4. 8 volts. This
setting should be made at room temperature of
approximately 68°F. If the system must operate
under other temperature conditions, use the graph
of Figure 95 to determine the range of allowable
reference voltage settings.
DC volh
measured with
retpec: t to the
-3 volt level
at any 806 pin
5.0+------------
<l.9~._,.'.;.!;,~· :?:Si;;;;::::.;;;;;:=====
<l.&-io :;;;iAll°"'ob1._
<1.7 -t==~ ..... li!i~(;;.!.. . e R~o:rig~e~·=···:::r.:::;;;
<l.6 e:...... ''..:31: • .:.iii
<1.5 ~
<!.<!+------------~
<l.3+------------
<1.2-+------------
<I.I _+------------
10°c
so°F
FIGURE 95. SP REFERENCE VOLTAGE TRACKING
102 (3/71) Model SO FEMM
With the room temperature between 680-S6°F,
the storage protect storage should operate with the
reference voltage varied ±0. 4 volts from its nominal
point. Before checking this variance, however, be
sure that all logic voltages and the sense level volt-
age are at the nominal points.
Sense Level Voltage
The sense-level voltage is used by the final amplifier
to yield the best discrimination between a maximum
zero and a minimum one. As an initial setting, adjust
the sense- level voltage to 3. 1 volts (measured be-
tween 02B-A3J4B02 and ground).
To find the optimum setting, run the storage pro-
tect diagnostic (E3C9) with all the logic voltages and
the reference voltage at their nominal values.
Lower the sense- level voltage (top potentiometer
at 02B-A3J4) until the first error occurs. Return to
the nominal value, restart the program, and raise
the sense level until another error occurs. Set the
sense-level voltage at the mid-point of the high and
low values.
With nominal logic voltages and nominal room
temperature, the storage protect storage should
operate with the sense-level voltage varied ±0. 2 volts
from its nominal value.
Checking SP Drivers and Terminating Diodes
See the section entitled "Checking MS Drivers and
Terminating Diodes" under "Main Storage (MS)
Service Checks."
Inhibit Drivers and Sense Amplifiers
Figure 96 shows the location of the inhibit drivers
and sense amplifiers for the storage protect storage
Bit
Location Out (Inhibit)
Retum Sense Pin line Name
I
8-AJL<I
808
807 802
Parity
2
8-AJLJ 803
810
80<I 0
3
8-AJJJ
808 807 802
I
•
8-A3L4
803 BIO 804 2
s
B-A3L3 808
807
802 3
•FIGURE 96. SP INHIBIT DRIVER AND SENSE AMP LOCATIONS
SP Sense Windings
Figure 97 shows the location of the storage protect
storage sense windings. The sense windings may
be scoped using a one-to-one probe and the differ-
ential amplifier feature of the scope to cancel noise.

IBM System/360 2050 Specifications

General

Brand	IBM
Model	System/360 2050
Category	Computer Hardware
Language	English