Section 5
TM6564-C-00
26 April, 2011
5-1
5. MAINTENANCE AND TROUBLE SHOOTING
5.1.
PERIODIC MAINTENANCE
There are no adjustments or controls in the scanner. Each relay should be operated at least
a 10 times in a given month to ensure they do not become stuck in a fixed position and that
the contacts are kept clean.
5.2.
UNSTABLE READINGS
The most common cause for unstable readings is poor connections between the units being
measured and the scanner inputs. Loose connections or leads that are oxidized or unclean
will cause unstable readings. The leads should be shiny and can be restored by lightly
sanding with fine sandpaper and/or cleaning with isopropyl alcohol. Periodic cleaning of
the leads and tightening connections may improve your readings. Ideally gold flashed
copper banana jacks should be used for connection to scanner terminals for best contact
quality and reliability.
Scanner channels that are used less than once a month may develop a film on the relay
contacts. The relay contacts are wiped clean each time they are used; however, if a relay is
not used for a while the film may not be wiped clean with only one closing of the relay.
Infrequently used relays should be switched on and off a few times before use. This can be
done from the front panel or by using the Relay Exercise routine in the TeraCal software
program.
5.3.
RELAY FAILURES
Relay failure is just about the only cause of scanner malfunction. All relays are carefully
adjusted and very thoroughly screened. Improved relay drive circuits have minimized but
not yet completely eliminated these failures. The channel indicator light staying on or off
can identify a bad relay that will not open or close.
Note: If one relay hangs up on the closed position, no other relays in the line can be
closed. The protect circuit prevents more than one relay on a line from closing. See
section 4.5 for protect circuit.
