Section 1. Basic Unit - IBM 5410 Maintenance Manual

Section 1. Basic Unit
The only adjustments and repairs possible in the CPU are
to the power supplies (see Chapter 5), and the bridge basic
storage module (BSM). If 8K, l 2K, or 16K of storage is
installed in the CPU, it is in an 8K or l 6K BSM at location
01 A-B4. If 24K or 32K of storage is installed in the CPU,
three types of BSMs can be used. For early systems, 24K
of storage uses an 8K BSM and a 16K BSM chained to-
gether. For later systems, a 32K BSM is used for both 24K
and 32K of storage. A 48K storage system uses a 32K BSM
and a 16K BSM chained together; 64K storage (RPQ
S40048) uses two 32K BSMs. When two BSMs are chained
(dual BSMs), they are at locations 01A-B4 and 01A-A4 in
the CPU. When one 32K BSM is used, it is at location
01A-B4.
BSM Sizes Required
Storage
Capacity SK 16K 32K
SK 1
12K 1
16K
1
24K 1
and 1
or
1
l
I
32K 2 or
1
_l
-,
48K
1
and
1
l
64K
2
For reliable storage operation, the BSM diagnostics should
run two minutes without errors when the -30 volt XYZ
Page of SY31-0244-2
Revised December 1, 1971
By
TNL: SN31-0307
Chapter 4. Checks, Adjustments, and Removals
drive voltage is biased 1 .2 volts in either direction from its
initial setting. If BSM operation is unreliable, either a fault
exists, XYZ drive voltage (-30V) reoptimization is required,
or strobe setting and -30V reoptimization is required.
Proper settings for the -30V power supply and the strobe
settings for each BSM are recorded on a decal located on
the XYZ current limiting resistor cover (Figures 4-1, 4-2,
and 4-2B).
Note: The memory thermistor automatically changes the
-30V oower supply to compensate for temperature changes.
For each degree F temperature change there is a 75 mV
change to the -30V power supply.
The only repairs possible on the BSM are card replacement,
voltage and strobe adjustments, and repair of minor (visible)
shorts or open circuits. Major array failures (shorted diodes,
internal opens, etc.) necessitate BSM replacement.
Most problems fall into two categories of component
failures:
1. Circuit failures (card, loose connector, etc.)
2. Array failures (shorted lines, open line, diode, etc.)
Intermittent or random failures are treated separately.
5410 MM 4-1