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Service
Key Sequence
(None)
SHIFT FLOAT
1
OFF
(None)
SHIFT FLOAT 2 OFF
(None)
SHIFT OUTPUT
1
OFF
(None)
SHIFT OUTPUT 2 OFF
Annunciator
FLOAT
1
FLOAT 2
ON
1
ON
2
Status
IC
on A2
U38
u35
u2
u2
On
Off
Pin Level
(lTL)
13 L
H
13 L
H
16
L
H
17
L
H
On
Off
On
Off
On
Off
Model
8904A
3.
HP-IB
Annunciators
Check
a. On the Multifunction Synthesizer, press
SHIFT PRESET.
After
the instrument presets, key in
SHIFT SERVICE
NEXT NEXT
f3
(Memory
Map
Access)
NEXT NEXT
The four front-panel, HP-IB annunciators
(RMT, LSTN,
TALK,
and
SRQ)
should be on. (Pins
15,
14,
13, and 12, respectively, of U2 should all be
TTL
low.)
b. Key in
0
F.
The HP-IB annunciators should be
off.
(Pins 15,14,
13,
and 12 of
U2
should be high.)
Note:
J1
is the
22
pin connector on the front right edge
of
A2.
Pin
1
is nearest the center
of
the
board. The
+5V
supply is on pins
1
and
2
of
J1.
8-40
Troubleshooting (Digital/Keyboard Interface)