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5.5 TROUBLESHOOTING
The troubleshooting
instructions contained in this section are
intended for qualified personnel having a basic understanding
of analog and digital circuitry. The individual should also be
experienced at using typical electronic test equipment as well
as ordinary troubleshooting
procedures.
The information
presented here has been written to assist in isolating a defec-
tive circuit or circuit section; isolation of the specific compo-
nent is left to the technician.
5.5.1 Recommended
Test Equipment
The recommended test equipment to troubleshoot the Model
706 is listed in Table 5-4. The test equipment may vary but
the specifications must be at least equal to the specifications
listed in Table 5-4.
Table
5-4. Recommended
Test
Equipment
Equipment
Use
Five function DMM with
Power supply and DC
0.05% basic DC accuracy
voltage checks, contin-
(Keithley Model 179A or
uity, logic levels.
equivalent)
Dual trace, triggered-
Waveform checks
sweep oscilloscope, DC to
20MHz bandwidth
5.5.2 Digital
Self Test
Upon power-up the Model 706 performs a number of tests
and displays several messages. These tests and messages are
explained in paragraph 2.3. The Model 706, also upon power
up, and upon activating Program 99 performs a digital self
test on the RAM circuitry and a cyclic redundancy check
(CRC) on the ROM circuitry. If the digital self test of the RAM
circuitry reveals a problem the Model 706 displays the follow-
ing:
1 LRRRRRRI
If the CRC reveals a problem the Model 706 displays the
following:
/ 1 ua000a
. . . . . .
This display indicates that there is a problem with the Model
706's ROM circuitry. In either of these two cases, the Model
706's memory circuitry should be checked. The
cause of the
problem could be that a memory chip is loose in the
socket.
Upon
actuation
of front panel Program 8 the Model 706 per-
forms a digital self test and a CRC of the RAM and ROM cir-
cuitry respectively. If the digital self test reveals a problem
with the RAM circuitry the Model 706 displays the following
for approximately 0.5 seconds.
I-R
After this display the Model 706 displays the following:
I FffII
I
I
!
If the CRC reveals a problem with the ROM circuitry the
Model 706 displays the following
for approximately
0.5
seconds.
l-c?
After this display the Model 706 displays the following:
I FRII
I
I
1
If the self test and the CRC both reveal a problem, the Model
706 displays the RAM
and
ROM error messages and then
displays the fails message.
When either test does not reveal a problem (using Program 8)
the Model 706 displays the following message that indicates
both tests have passed.
Table 5-5.
Power
Supply
Checks
Step
Item/Component
Required
Condition
Remarks
1
S101 Line Switch
Set line voltage
as
required.
See paragraph
5.3.
2
FlOl Line Fuse
Continuity
Remove fuse to check.
3
JlOOl Line Power
Plugged into line receptacle:
power is on.
4
AC input to supply. 2 pin Molex Connector
Line voltage (100, 120, 220, or 240V)
5
+6V supply terminal +6V terminal referenced
+6V +5% (5.7V
to
6.3V)
+6V supply
to the terminal.
5-6
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