That's interesting. Does it come back or get worse at high sweep speeds?
Nope, no change even at high sweep speeds. It's currently rock solid. I even gave it X10 sweep boost and it's fine. ![Confused :-//](https://www.eevblog.com/forum/Smileys/default/confused0024.gif.pagespeed.ce.5xOqKkq0Co.gif)
Hmmm...
Have you tried heat applied to components in the suspect circuit? Alternately, cold spray from an inverted can of canned air.
I don't think the issue is heat related because it occurs right at power up. I do have freeze spray but I'm very reluctant to use it in that area. Too near HV and the freeze spray once it condenses forms droplets. Hilarity will ensue I'm sure. Not a good idea.
I put the Siglent DSO to good use and I did manage to find the retrace pulse to the CRT grid on the Z Axis board. This is a “good” pulse. The scope is functioning normally. If and when it goes south again I have a starting point. Probe that point again and see what the pulse looks like and take it from there.
![](https://imagizer.imageshack.com/v2/xq90/922/NyAjCi.jpg)
Since I had the knickers down (covers off) I figured I might as well take some superfluous pron shots. Enjoy!
![ThumbsUp :-+](https://www.eevblog.com/forum/Smileys/default/icon_smile_thumbsup.gif.pagespeed.ce._JElyJQqdB.gif)
The Horizontal Board. All discrete components unlike bd139's 7603 which is IC.
![](https://imagizer.imageshack.com/v2/640x480q90/921/EOoiLB.jpg)
Vertical Board under the Horizontal Board.
![](https://imagizer.imageshack.com/v2/640x480q90/924/vQgnJn.jpg)
Z-Axis Board on top of the HV case. In the back is the Regulator Board with the -50V reference adjustment pot on the top right. Just under that is the linear power supply and transformer. BTW, this scope has no fan. Some 7603's do and some don't. Seems Tek couldn't make up it's mind if one was really needed.
![](https://imagizer.imageshack.com/v2/640x480q90/921/pmqumZ.jpg)
Towards the front is the Calibrator Board.
![](https://imagizer.imageshack.com/v2/640x480q90/924/ONf2gS.jpg)