Teletype SA110 Checkout And Troubleshooting page 2

SECTION 578-200-300
possible. If records have been kept of the error rates from
various senders, select the best one regardless of its age or
location. If the error indication is a line break (SA110 AB,
SA110 BA, and SA110 CA), a telephone connection must be
established to the sender for the operator there to report on
the indications received.
-2.05 When a local sender is used for either a 33 or 35
type set, the data connection to the terminal
should be established in the usual manner as though the
SAll0 were not there. If there is more than one local sender
to choose from, pick the one most likely to have the lowest
overall error rate. This will probably be a new sender, or one
recently readjusted, unless error rate records have been kept
and show otherwise.
2.06 Transmit correct-parity copy to the SA110 for 15
minutes. If the copy is printed correctly and no
line breaks are generated or errors counted, or if an
occasional line break is generated or error counted and a
corresponding error is observed in the copy (remote sender
only), the SA110 can be assumed to operate properly with
error-free copy. If the copy is garbled, refer to Part 3.
If
the
copy is printed correctly, but errors are indicated continu-
ously from a remote sender or if any errors are indicated
from a local sender (except a 33 sender when the SA110 is
strapped for the significant distortion check), refer to Part 3.
If the copy from a remote sender is printed correctly but an
occasional line break is generated or error counted, or if an
occasional error appears in the copy which is not indicated,
extend the test for several more minutes. This will determine
whether normal false indications (caused by the parity bit
only being in error) or nondetectable errors occurred or
whether the SA 110 is defective.
If
further failures occur reg-
ubrly, refer to Part 3.
Note: The direct output of a 33 type sender,
depending on its age and condition, may contain noise
spikes which can trigger the significant distortion check
circuit in the SAl 10. A very high percentage of errors
may be indicated under these conditions. To check for
SAl 10 operation under normal service conditions when
only a 33 type sender is available, cut strap C on card
MC402 in the SA 110 chassis to remove the significant
distortion check. Be sure to solder strap C closed at the
conclusion of checkout if the significant distortion
check will be used in service.
B. Parity Error Detection
2.07 A tape containing parity errors can be prepared
using either a nonparity or a parity keyboard. If an
ASR set with a nonparity keyboard is available it would be
easier to use it. (To determine if the keyboard on an ASR set
is nonparity, turn on the set and depress the A key several
times. If three holes arc punched in the tape, the keyboard is
non parity.) Make a test tape using the format of Figure 1. If
an ASR set with a nonparity keyboard is not available, use
any ASR set and make a test tape as shown in Figure 2.
(RETURN)
CEFIJLOQRT~X AEXERTBEXERT ATWXBTWXDTWX QUESTMDPRAIO ABDGHKMNPSUV
Note: Space once between each group of 12 letters. First group has no parity errors,
second group has two (A and B) with five good characters following, third group
has three (A, B, and D) with three good characters following, fourth has alternate
correct and incorrect parity (six errors - U, S, M, P, A, and D), and last group has
12 consecutive errors.
Figure 1 - Low Speed Parity Error Test Tape Using Non parity Keyboard ( 8th Bit Marking)
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