Daikin SUPER MULTI NX G Series, Service Manual

Page: 233 / 244

SiUS12-928_A Application of Silicon Grease to a Power Transistor and a Diode Bridge
Trial Operation and Field Settings 224
4. Application of Silicon Grease to a Power Transistor
and a Diode Bridge
Applicable
Models All outdoor units using inverter type compressor for room air conditioner.
When the printed circuit board of an outdoor unit is replaced, it is required that silicon grease (*1) is
applied to the heat radiation part (the contact point to the radiation fin) of the power transistor and
diode bridge.
*1: Parts number of the silicon grease – 1172698 (Drawing number 3FB03758-1)
Details The silicon grease is an essential article for encouraging the heat radiation of the power transistor
and the diode bridge. Applying the paste should be implemented in accordance with the following
instructions.
Note: There is the possibility of failure caused by smoke from bad heat radiation.

Completely wipe off the old silicon grease on a radiation fin.

Eevenly apply the silicon grease to the whole.

Do not have any foreign object such as solder or paper waste between the power transistor, the
diode bridge and the radiation fin.

Firmly tighten the screws of the power transistor and the diode bridge, and to securely connect
them to the radiation fin without any gap.
<Example>
(R9056)
Take out a PCB
Not applied.
OK : Evenly applied
Paper waste
Diode bridge
(Diode bridge, Rectifier stack, etc.)
Power transistor
(TRM, TPM, IGBT, IPM, SPM, etc.)
silicon grease.
NG : Not evenly
applied
NG : Foreign object.