Lucent Technologies Lineage
®
2000 400A, 60Hz Ferroresonant Rectifier J85503C-3
Issue 10 July 2000
Spare Parts and Replacement Procedures 8 - 15
Thyristors (Q1, Q2)
1. Remove the wires attached to the thyristor. Note their position for
reinstallation. The T4013NK thyristors, originally in the rectifier,
use a beryllium ceramic. If the case is cracked, the manufacturer
(Semiconductors Ltd., A Ratheon Company) recommends the
component be handled with gloves, placed in a plastic bag, and
sealed before discarding. The replacement part does not use a
beryllium ceramic.
2. Remove the two nuts that secure the thyristor to the heat sink.
Save the nuts and the thermal pad from under the thyristor.
3. When reinstalling a new thyristor, use the hardware and thermal
pad (DP102 comcode 403208242) saved in Step 2. Note that the
small gate terminal always faces down. Torque the mounting nuts
to 10 in-lb. Reconnect the wires to the new thyristor.
Diode Heat Sink
Assemblies
1. Remove the nuts securing the pigtail of the diode to be replaced
from the power transformer.
2. Use a meter with a diode test function (or measure the forward and
backward resistances of the diode) to determine if the diode is
good. A good diode should measure at least 50 ohms in both
directions, and one direction should measure at least 50 times the
other. The larger resistance is the back resistance, and the smaller
is the forward resistance. Most diodes that fail do so by shorting
(i.e., they will measure shorted or almost shorted in both
directions).
3. If the diode checked bad, replace it. If the diode checked good,
reinstall it.
4. Remove the nut on the back side of the diode. Save the thermal
pad and nut. Cut cable tie securing the pigtail lead.
5. Reinstall diode with thermal pad. Dress pigtail lead away from any
sharp corners. Torque diode nut to 300 in-lbs. Torque pigtail
connection to transformers to 135 in-lb. Reinstall cable ties.
