Quote:
Originally Posted by TinCanAlley
I thought I wasn't supposed to go near the HOT w/out a hi voltage probe? Also, whose idea was it to make a transistor with the shell being the collector? Wouldn't it have been easier to make it a three lead unit and then you wouldn't have to worry about isolating it so as not to short to ground? I looked over the thing carefully and found the case is being energized by a lead on the screw hole.
|
The high voltage retrace pulse is developed at the collector of the HO transistor, so if the transistor is removed, it does not occur, and you will be able to read the base waveform with an ordinary 10x probe.
The transistor collector is the substrate of the die, which has to be soldered to the case to get good thermal conductivity to the heatsink. Hence, the case will be connected to the collector. There will be an insulating washer and some thermal-conducting (but electrically insulating) grease.