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Weird 466 horizontal glitch

Edward Prest
 

My new to me 466 2nd version has a strange issue.
I see a background image related to the display. Hard to describe so there is a picture in photos under Edward Prest.
It may be a blanking issue or a horizontal issue. I see two lines at the peak and valley of all signals across the CRT. There is no DMM. I have to turn up the intensity some to see them. The bright parts do interfere with the display. Sine or square - same issue - only at the peak and valley. In the images the positions are shifted far to the side to show the artifact clearly. Shifting it left or right has a tiny effect but more or less glitch remains in place.

I have the service manual but its a big read and it will take me a while before i dig in. I have measured the power supplies, all low voltage rails are are just barely above the book spec except for 140v which is 127V - a few volts under min spec.

(p.s. I am using 60hz line noise for the sine wave in the image -that's all I have for the moment)

Mlynch001
 

Edward,

I am going to ask what may seem a stupid question. Have you cleaned the "Beam Finder" switch? I have a 465 that was doing something similar. It had a dirty beam finder switch. The switch SEEMED to be releasing, but in reality, it must have contained some sort of conductive crud inside, this caused some of the contacts to remain on (or partially on) when they should have been off. Clean with recommended cleaner, I use DE-OXIT after cleaning and vigorously exercise the switches. These switches can do some crazy things. Go after the simple stuff first, you might be pleasantly surprised.

--
Michael Lynch
Dardanelle, AR

Edward Prest
 

Good idea.
With beam finder pressed, it does not show the problem.This is an important clue!
in xy mode it does glitch too, as every other setting.

I have checked Z output and its clean. (it leaks the z sum even though its an input)

more reading the manual with emphasis on the differences with beam on and off next i guess

Mlynch001
 

On Sat, Feb 22, 2020 at 08:23 AM, <prest.edward.3@...> wrote:


Good idea.
With beam finder pressed, it does not show the problem.This is an important
clue!
in xy mode it does glitch too, as every other setting.

I have checked Z output and its clean. (it leaks the z sum even though its an
input)

more reading the manual with emphasis on the differences with beam on and off
next i guess
Edward,

I have found that dirty/sticking switches are a major problem in these old scopes. I have had several 4XX Series scopes across the bench that were "Cured" by a simple and thorough cleaning of all these type of switches. Good luck in your repair.

--
Michael Lynch
Dardanelle, AR

Edward Prest
 

Tomorrow I will squirt cleaner in it. if no joy there, then scope the
rails is next.
While the primary z axis input looks clean, there is vertical board input
one transistor after this z input. very suspect.

On Sat, Feb 22, 2020 at 9:54 AM Mlynch001 <@mlynch001> wrote:

On Sat, Feb 22, 2020 at 08:23 AM, <prest.edward.3@...> wrote:


Good idea.
With beam finder pressed, it does not show the problem.This is an
important
clue!
in xy mode it does glitch too, as every other setting.

I have checked Z output and its clean. (it leaks the z sum even though
its an
input)

more reading the manual with emphasis on the differences with beam on
and off
next i guess
Edward,

I have found that dirty/sticking switches are a major problem in these
old scopes. I have had several 4XX Series scopes across the bench that
were "Cured" by a simple and thorough cleaning of all these type of
switches. Good luck in your repair.

--
Michael Lynch
Dardanelle, AR