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Chapter 7 - Exchange of Thyristors for Size A7
DCS 500 / DCS 600 Service Manual
VI A
7 - 5
Install new thyristor
1. Ensure that the new thyristor is of the correct type (
of this manual). Keep the semiconductor and its surroun-
dings clean. If necessary clean them with a piece of tissue pa-
per 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 thy-
ristor, if necessary use a rubber spatula.
Figure 7-5
Prepare disk type thyristor
3. Clean all parts with tissue paper moistened with solvent, witch
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.
4. 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.
5. Turn the thyristor so that the gate leads point in the right directi-
on.
6. Connect the gate leads if possible.
7. Tighten the nuts of the mounting clamp by hand so that the
clamp is in parallel with the contact surface of the heat sinks.
3ADW000093R0701_DCS500B/DCS600_Service manual_e_g