Teletype SA110 Checkout And Troubleshooting page 10

SECTION 578-200-300
SAll0 PARITY FAILURE DETECTOR TROUBLESHOOTING CHART (continued)
NO.
TROUBLE INDICATION
ANALYSIS AND RECOMMENDED ACTION
2.
i. If the voltage measured in step h fluctuates near +3 volts
(cont)
(from Oto +6 volts), measure the voltage between slip
connector terminals 2 and 10 (EIA output) or 2 and
12 (all other outputs) on card MC405 while a message is
being received. If this voltage is a steady +6 (±1) volts
(EIA), 0 volt (signal line), or +8 (±2) volts (l0lC or
105A data set), the output amplifier (8538WD) is defective.
Repair it or replace card MC405 (TP322405).
j.
If
the voltage measured in step i fluctuates near 0 volt
(EIA) or +4 volts (all other outputs), check the contacts
and wiring on the PARITY CHECK switch (8566WD or 8567WD)
and connections to the terminal. Repair any faults found.
3. Terminal receives garbled
a. Check SAll0 data input and output terminals for loose
copy when SAll0 PARITY
connections or connections made to wrong terminals
CHECK switch is ON.
(8716WD or 8717WD). Correct any faults found.
b.
If data connections are good, check straps A and B and
terminals 10, 11, and 12 on card MC402-04 to determine
if they are strapped for the unit code being received
(Section 578-200-200 and 8538WD). Change strapping
if incorrect.
c. If straps A and Band terminals 10, 11, and 12 are
strapped correctly, either card MC402-04 (TP322402-04)
or MC405 (TP322405) is defective. Replace either card
first to isolate trouble or replace entire SAll0.
/
4.
Parity errors arc not detected
a.
If no parity errors are detected, check strapping of
(some or all).
terminals 7, 8, and 9 (8538WD). Carefully resolder correct
strap if both are open ( do not keep soldering iron on ·
strap any longer than necessary to obtain a good joint, or
the heat may loosen the ends of the strap).
b.
If strapping of terminals 7, 8, and 9 is good, or if some
parity errors are detected, either card MC402-04 (TP322402-04)
or MC405 (TP322405) is defective. Replace either card first
to isolate trouble or replace entire SAl 10.
5. Significant distortion errors
a. Check strap C on card MC402-04 to be sure it is properly
arc not detected (parity error
closed (zero resistance). Carefully resolder it if necessary
detection normal).
(do not keep soldering iron on strap any longer than
necessary to obtain a good joint, or the heat may loosen the
ends of the strap).
b. If strap C is properly closed, MSFF, SMFF, and DDFF circuit
on card MC402-04 (8538WD) is defective. Repair it or replace
card MC402-04 (TP322402-04).
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