Horizontal output transistor (HOT) replacement help

[oldmumak]

Hello,

I'm replacing the HOT in my WG7900. Do I use thermal paste on the clear plastic piece that goes in between the HOT and the heatsink? Also the old one is D1398 2G4, the new one is D1398 6G3. What do the last numbers mean?

[Kevin Mullins]

Do I use thermal paste on the clear plastic piece that goes in between the HOT and the heatsink?

A thin layer on both sides of the mica insulator. (clear plastic piece)
I typically apply the thermal paste to the HOT, stick on the insulator, then apply thermal paste to the insulator, then attach HOT to the heatsink.

Also the old one is D1398 2G4, the new one is D1398 6G3. What do the last numbers mean?

Most likely manufacturer / date code type info..... the D1398 is all that is relevant.

[oldmumak]

  thank you