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<Toc> < 4. Troubleshooting and Maintenance >
IM 05D01C02-41E 3rd Edition: May 31, 2006-00
4.2.4 Replacing Parts with a Limited Service Life
The follwing UT550/UT520 parts have a limited service life. The service life given in the
table assume that the controller is used under normal operating conditions.
Part Service life
Aluminum electrolytic condenser About 10 years (rated)
EEPROM About 100,000 times of writings
Alarm output relays About 100,000 more ON-OFF operations or with resistance load
Control output relays About 100,000 more ON-OFF operations or with resistance load
If any of these parts, except control output relays, cause a controller failure due to deterio-
ration, contact your dealer for replacement at your cost.
See Also “4.2.5 Replacing Control Output Relays”, for how to replace the control output
relays.
4.2.5 Replacing Control Output Relays
This section describes how to replace the control output relays.
Since inspection is needed in case parts are replacement will be carried out by a
YOKOGAWA engineer or an engineer certified by YOKOGAWA. When replacement is
required, contact your nearest YOKOGAWA dealer.
CAUTION
Always turn off the power before starting the work in order to avoid electric shock.
Do not pull out the internal unit for any other purpose other than to replace the control
output relays.
1. Insert a flat-blade screwdriver (tip width of 6mm is recommended) into the opening (4
openings are on the top and bottom of bezel) with the tip in parallel with the front panel,
and then turn the screwdriver gently.
Take this procedure to four openings 1, 2, 3, and 4 (see the figure below) on the upper
and lower parts of the bezel, in order.
The bezel slightly moves forward from the housing.
1
2
4
3
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