Table of Contents
Advertisement
4.1 FAULT LOCATION
lf a failing pattern is not already evident, try manually
storing and displaying or scanning storage to establish a pat-
tern. If this fails, run storage diagnostics.
4.1.1 Circuit Failures
All BSM problems should be approached as if there has been
a circuit failure. Circuit failures (card, connector, etc.) can
be broken into distinct patterns. For example:
• Single bit-all addresses
• Single bit-one block of addresses
• Multiple bits-all addresses
• Multiple bits-one block of addresses
The 'all addresses' failure could be caused by the drive cur-
rent source card or the control driver card (Figure 4-3). The
'block of addresses' failure could be caused by a defective
gate driver card. For example, if SAR bits 7, 8, and 9 are al-
ways active in the failing address, the chart in Figure 4-3 in-
dicates the failure could be the Y-lo gate driver.
Single-bit or multiple-bit failures can be caused by a sense/
inhibit card which also contains the SDR latch for that bit.
Card location:
Note: Bits 9-17
are 0-8 when
SAR bit 2 is
active. Bits 8
and
1
7 are the
p bit.
Bits
0, 1,2
3,4,5
6, 7,8
9, 10, 11
12, 13, 14
15, 16, 17
Bits
0, 1
SKBSM
16K BSM
XXJ4
XXJ4
XXH4
XXH4
XXG4
XXG4
-
XXF4
-
XXE4
-
XXD4
32K BSM
XXK4
Page of SY31-0244-2
Revised December 1, 1971
By TNL: SN31-0307
Multiple-bit failures at all addresses can also be caused by
the strobe driver card. (For card location, see ALD page
SR224.)
Using bridge
MAP
charts (trouble analysis flowcharts) allows
repair of most of the failures by swapping
or
replacing cards.
Use the
CE
pocket meter and diagnostic probe for help in
locating and repairing the trouble.
4.1.2 Array Failures
If the array fails, replacement is necessary unless the failure
can be traced to cabling defects, visual defects, or an open
diode. Trouble caused by open diodes can be replaced by
. patching a new diode across the open one. Shorted diodes
require replacing the array.
4. 1.2. 1 Single Bit, Multiple Address Failures
A sense/inhibit (S/Z) problem usually shows up as an extra
or missing bit throughout an 8K block of storage (each S/Z
line passes through 8, 192 cores). If the S/Z card is not at
fault, check the wiring to the Z load resistor. (Refer to
SR071-076 and to SR264 for locations.) Check that -30
volts appears on pin 2 of the affected resistor.
Check also for a broken S/Z wire between the array and the
~
I
back panel pins on the sense amplifier. (See Figure 4-2D for
~
the numbering of the pins on a core plane.) A complete S/Z
winding resistance should measure approximately 14.0 ohms.
If the open or shorted S/Z winding is within the core plane,
replace the BSM.
Top
One Core
Plane
2,3
XXJ4
Side B
~
Diode
4,5
XXH4
Board ·
r-
6, 7
XXG4
(see SR204)
Side D
8,9
XXF4
10, 11
XXE4
12,13
XXD4
14,15
XXC4
16, 17
XXB4
•Figure 4-20. Numbering of Core Plane Pins
5410 MM
4-3
Advertisement
Table of Contents
