Great, my VT52 is shot.

[Mattis Lind]

söndag 19 april 2020 skrev Chris Zach via cctalk <cctalk at classiccmp.org>:

> Well, let's see: I took the bottom off the VT52 and checked the
> connections to the high voltage board on the back. Cleaned up both
> connectors, plugged in, same problem.
>
> I do hear a medium to high pitched squeal coming from the back board.
> Can't quite triangulate it (I need a hose and some time) but it might be
> coming from those center transistors. Any idea what these boards are doing,
> and if there is a schematic for these circuits?


The left is the video /CRT part. The right is the power supply part. The
transistors are mostly regulator transistors.

I have linked to both maintenance manual and schematic from the page I
referred to in one of my previous replies to this thread.
http://www.datormuseum.se/home/dec-vt5x

Take a look there!

/Mattis



> Given that it went weird after being powered on for awhile I would suspect
> it has something to do with a component that generates heat. I could also
> take an IR picture of the back board and see if anything is unusually
> hot/not hot.
>
> Audio of the noise: https://i.imgur.com/ps4Ovkj.mp4
> Pic of the back: https://i.imgur.com/HgNoTYK.jpg
>
> C
>