IBM 5280 Manual page 49

D
2
BASE MAP
MAIN MPU ATTN ERROR
PAGE
3 OF
4
008
(ENTRY POINT AA)
- Install terminating resistor
(PN:4177566) (5.lK) from A-A4D03
to A-A4D06 (MIM 501).
- Probe A-A4D06 ' - ATTN from
KBD/Disp' (MIM 501).
- Observe the lights as you
momentarily ground the jumper to
frame ground.
- NOTE: The pulse may be delayed 3
to 4 seconds.
Up Light: On
Down Light: Pulse
Are the lights correct?
Y N
009
The logic board is open
ATTN to KBD/Di sp' <tUM 531).
- - - - - OR - - - - -
- Defective Keyboard/Display MPU
card (A-AI) (MIM 200).
If a 'Ros Patch' cable is
connected to the card,
GO TO MAP 0600, ENTRY POINT A.
010
(ENTRY POINT B)
The logic board is open ' - ATTN
from KBD/Disp' (MIM 531).
- - - - - OR - -
- Defective Diskette/Main MPU card
(A-Cl) <t-lIM 303).
If a 'Ros Patch' cable is
connected to the card,
GO TO MAP 0600, ENTRY POINT A.
A
1
MAP 0511-3
all
(ENTRY POINT C)
- Power Off.
- Check the Attention line(s),
that match
the probe light
condition, for a ground.
- Use the CE voltmeter set to the
RXI scale.
- Connect the C.E. voltmeter to
the probe point for the failing
Attention line(s).
Does the meter have a 5 ohm or
less reading?
Y N
012
- Defective MPU card for the
attention line(s) that match
the probe condition (MIM 501).
- If a 'Ros Patch' cable is
connected to the card,
GO TO MAP 0600, ENTRY POINT A.
013
- Remove the Diskette/Main MPU
ca r
d (A-C 1) (M I M
501).
Check
that
the Attention line(s),
match the probe light
condition, for a ground.
Does the meter have a 5 ohm or
less reading for ANY line?
Y N
4
E
014
- Defective Diskette/Main MPU
car d (A- C 1) ( M 1M3 0 3) .
If a 'Ros Patch' cable is
connected to the card,
GO TO MAP 0600, ENTRY POINT A.
EC840S74
PECS397S7
MAP 0511-3