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-
Read Call (B2A3D11)
2V/cm
- X
Write Current Source (B2U5D06)
lOV/cm
0
-~~!!:!+W;!;j;±t;!:~±!i'~f*+'f""~~:!;!:!:!;I-
Y Write Current Source (B2U4D06)
lOV/cm
100 ns/Div.
Figure 1-129.
X-Y Write current at
Resistors for looping and
scanning procedures.
1.25.2.2 Scoping Inhibit Drive
~errrinating
Resistors
Inhibit drive current can be checked
in
the
same way as read or write currents by
:E=rcbing the current-limiting resistors
ass:>ciated with each inhibit driver.
The
z
inhibit driver source is
essentially two
NPN
transistors
in
parallel, each transistor having a 70-ohm
wire-wound resistor in series with the
erritter.
These resistors are mounted on
the swing-open side of the
ESM
gate.
The
black and red wires are returned to the
z
driver card.
The yellow wire is corrrron
-30V..
A r;air of resistors is, therefore,
corrrnon to each particular bit position and
is also corrmon to the 0-8K segment A and B,
and 8-16K segment A and B.
The current prcbe can be used on the
yellow wire, and the voltage probe at the
red or black side of the resistors.
The
resulting waveforms of a correct inhibit
driver are shown in Figure 1-130.
Approximately 760 mA is shared between
the
70-oh~
resisters (380 nA through each).
The voltage swing should be approximately
26V at the read and black wire side of the
resistors.
Substitution of the sense amplifier/Z
power card can deterrrine the failing
location.
1,.25.2.3 Array sense Line Checking
Two methods may be used for checking array
sense/inhibit lines.
Figure 1-131 identifies the method to be
used with the array plugged to the main
storage SLT board.
It is possible to meter
the connections between sense line input
pins and the inhibit
1
ine pin.
Figure 1-132 identifies the method to be
used with the array rerrcved from the
machine.
(The removal procedure is
described in Chapter 4 cf this manual.)
- Read Call (B2A3D TT)
(2V/cm)
0- -------+-_,t---+-_-t-_______
-Z lnh ibit Res is tor
100 ns/Div.
(lOV/cm)
(Inhibiting a Zero)
(Line Inactive for a One)
-Y Write Current Source (B2U4D06)
(lOV/cm)
Figure 1-130.
Z-Inhibit Driver (Writing a zero)
1-132
(7/69)
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