47
Exchange of Thyristors for Size D5
3ADW000195R0501 DCS800 Service Manual e e
Install new thyristor
1.
Ensure that the new thyristor is of the correct type (
see Appendix A)
. Keep the
semiconductor and its surroundings clean. If necessary clean them with a
piece of tissue paper moistened with solvent.
Note:
Do not touch the polished surfaces of the thyristor.
2.
Clean the polished surfaces of the semiconductor with a piece of tissue paper
moistened with solvent. Dry all surfaces. Spread a thin layer of heat
conducting paste on both sides of the thyristor, if necessary use a rubber
spatula.
3.
Connect the gate leads if possible.
4.
Clean all parts with tissue paper moistened with solvent, which have had or will
have contact with the thyristor or each other (lower / upper heat sink). Do not
clean the surfaces of grease too thoroughly, because the aluminum surfaces
will oxidize in a few seconds. Dry all surfaces.
5.
Centre the thyristors by means of the spring pins.
Note:
Be sure that the thyristor is installed in the right direction. Do not pinch or cut
the gate leads or any other cable.
6.
Turn the thyristor so that the gate leads point in the right direction.
TORQUE INDICATING SPRING
Loose
condition
Correct torque
In
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s
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la
ti
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g
tu
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Insulating plate
Heatsink
Aluminum spring with welded indicating spring
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