Great, my VT52 is shot.

[Wayne Sudol]

Here's a link to the vt52 maintenance manual. Has testing and service info. Hope it helps.

 http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/terminal/vt52/EK-VT52-MM-002_maint_Jul78.pdf

Wayne

-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Chris Zach via cctalk
Sent: Saturday, April 18, 2020 3:56 PM
Cc: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Great, my VT52 is shot.

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?

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