IBM 5280 Manual page 85

A
K
I
2
DATA ENTRY MAP
A-AI DISPLAY
PAGE 13 OF 13
066
Power off.
Disconnect the Display
connector P20 (MIM 217).
- Power
on.
Check to see that the
Brightness Control and Contrast
Control are fully clockwise.
- Probe A-Al-TPlO, '+ Video
Dri ve' (MIM 200, 217).
Up light: On
Down light: On
Are the lights correct?
Y N
1
5
067
Probe A-A3B05, '1 MHz clock'
(MIM 531).
Up light: On
Down light: On
Are the lights correct?
Y N
068
For the line probed in the
previous step.
Up light: Of-f
Down light: On
Are the lights correct?
Y N
069
- Defective Diskette/Main
MPU card (A-CI) (MIM
303) .
If a 'ROS Patch' cable is
connected to the card,
GO TO MAP 0600,
ENTRY POINT A.
A A A
L 1' 1 N
A A
M N
MAP 1010-13
070
- Power off.
- Set the CE meter to the RXI
scale.
C0~~eGt the
positive lead to
A-A3B 05, '1 MH z clock', and
the negative lead to ground.
Is the meter reading 30 ohms or
above?
Y N
071
- Leave the meter connected
as in the previous step.
- Use the net list (MIM 531).
Remove each card in the
net, one at a time, until
the meter reads 30 ohms or
above.
- Replace
removed.
the last card
If all cards in the net
have been removed and the
meter reading is still
below 30 ohms, suspect a
ground on the Logic Board.
072
- Defective Diskette/Main MPU
card (A-Cl) (MH1 303).
If a 'ROS Patch' cable is
connected to the card,
GO TO MAP 0600, ENTRY POINT A.
073
Connect the CE meter from
A-Al-TP-12, 'Bri ghtness
Control', to ground (MIM 217).
The voltage should change from
a
to +5 Vdc as the Brightness
Control is turned clockwise.
Is the voltage correct?
Y N
EC340874 PEC339787
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