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1/2 o f screen vert ical green
bands, other half dots
Unreadable characters
Screen displays "garbage"
2 . 8
DISKETTE PROBLEMS
Both Si" and 8 " diskette problems are indicated through error messages
on the CRT when a diskette is addressed or are indicated by mechanica l
faults during the diskette drive operat ion .
are control led by the planar board
diskette problems may be caused by a fault in the diskette drive in the
diskette drive assembly in the processor unit or in the software or data .
If you are cont inuous ly receiving error mes s ages with the Si" and 8 11
diskettes as we l l as hard disks , the fault may be in the P3 - P800 cable .
See Figure S - 3S .
I f your system is equipped with disk or diskette as
s emb l ies , dis connecting the P3-P800 cable may a l l ow them to function . I f
s o , you need to have the cable replaced .
See Chapter 4 , "Cable Checks . "
check .
replacing, the system has to be returned to IBM for repair .
is not a customer - replaceable unit .
covers pos s ible mechanica l problems involving the diskette, and Section
2. 8 . 2, "Failure To Function" addresses pos s ib l e nonmechanical
prob l ems .
Feature board , p l anar board -
perform feature board loading check .
3 . 11. 2,
See Section
Loading Check . " Replace feature board
if mal funct ioning .
p lanar board .
CRT display unit, planar board - - Print
screen .
If print copy has unreadab l e
characters, replace p l anar board .
not , replace CRT display unit .
CRT display unit , p l anar board,
board
If t-lMU board is
check yel low LED on the MMU board . If
LED is off , replace MMU board .
is on or f l ashing or if no MMU board
is ins talled, print screen and perform
16 .
See Section 3 . 9 , "CRT Con
test
tro l ler Test - - Test 16 .
fai l s , replace p l anar board . If test
pas ses and pr int copy is readab l e
replace CRT disp lay
pas ses and print copy is
replace p lanar board .
Since the diskette drives
in
respon s e to the programmed data ,
The cable a lso has an optional
If the P3 - P800 cable should need
.
,
Section 2 . 8
1
Fault Detection 2-lS
"Feature
Board
If not , replace
If
MMU
installed,
If LED
If test
,
unit .
If
test
"garbage" ,
The cable
"Mechanical Fault s "
diskette
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