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Marginal Voltages
Progrcrn
Program
Normal
Ch
CPU
Local Storage
Main Storage
S toroge Prott>C r
Section
Description
Voltage
6M1
6M2
6TC
6VAR
56 XY
60Z
Vsl
Vref
Number
+6,0v
+6.0v
Opt
Opt
Opt
Opt
Opt
l .4v
+0.5v
+0.5v
±5%
±5%
±4.5%
±4.5%
±6%
• 10%
-0.5v
-0.5v
MIDAS
CPU Tests
l Poss
1 Pass
5340X
Diagnose and
1 Pas1
1 Pass
5341X
ErTOr Circuits
5342X
E381X
60 Cycle Int Timing
1 Poss
l Pass
E383X
50 Cycle Int Timing
l Poss
l Pou
F38FX
Meter Timing
1 Pass
1 Pass
5391X thru
Main Storage
1 Pou
1 Pass
1 Pass
S397X
Tetts
5066
53C1X
Local Storoge
2 Min
2 Min
2 Min
53C4X
Bump Storage
2 Min
2 Min
2 Min
! - - - · -I-·
· - -
E3C9X
Storage Protect
2 Min
2 Min
2
Min
2
Min
E421
x
thN
Mpx Channel
l Poss
1 Poss
E426X
1.Js;ng 1442
E428X thru
Mpx Channel
1 Poss
1 Pass
E42BX
Using 2540
E441 X thru
Sri Channel
1 Poss
1 Pou
E446X
Using 2400
Each Channel
F4DOX
Channel-to
l Pass
1 Poss
F4D1X
Ch..,nne I Feature
F4E1X
Direct
1 Poss
1 Poss
F4E2X
Control
5F01X
1~10
Emulator
1 Pass.
1 Poss
5F02X
Instructions
~-
1410 Emulator
1 Pass
l Pass
5F04X
Ch Translators
5F21X
7074 Emulator
1 Poss
1 Pass
5F23X thru
Instructions
5F2AX
5350
ROS R;pple
1 Poss
I Poss at limits of .. 12 ROS voltage
FIGURE 50. MODEL 50 DIAGNOSTICS
Flashing Lights
AAAAAA and 555555 in IAR alternating every four
seconds indicates output device not ready.
FFOOOO and OOFFFF in IAR alternating every sec-
ond indicates crisis.
MARGINAL CHECKING
Marginal checking is a technique used to detect the
marginal operation of the most voltage-sensitive
circuits in the system. These circuits have nominal
levels of voltage and current at which they are de-
signed to function. Each circuit operates within
certain margins (reir.ilator output voltage limits
above and below the nominal rating). However,
aging and other factors cause a gradual deteriora-
tion in the operating characteristics of the circuits.
By raising and lowering the regulator output voltage
within the design margins, it is possible to inspect
all the circuits powered by that voltage. On the
basis of this inspection, any circuit approaching a
failure condition may be replaced. This type of
check is made periodically as a preventive-mainte-
nance technique. Marginal checking is useful also as
an aid in locating operator-reported failures.
Costly down time and many trouble calls can be
avoided by using marginal checking to make failures
less intermittent and more recognizable.
Maintenance Features
(3/71)
75
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