Tektronix 4051 repair.

[Jon Elson]

On 09/21/2016 02:07 PM, Mattis Lind wrote:
> I took a look at the Tektronix 4051 that we got a few years back. After
> checking the PSU I turned it on and it seemed to start up fine. The machine
> responded well to the keypresses but it was hardly readable on the screen.
>
> Anyone that can give advice on what is wrong and how to deal with it. The
> text on the screen is very faint and many characters are scrambled as if
> the beam was moving when the points where plotted. When typing there is a
> flash of the beam which is then stored as the scrambled text.
>
> http://i.imgur.com/iQhQW67.jpg
>
> It probably reads "SYNTAX ERROR" something on the screen.
>
>
Whoa!  I think maybe some timing circuit has gone bad, 
probably due to bad electrolytic capacitors.
You might just leave it on for a while and see if it gets 
better. It also looks like some of the deflection drivers 
may be bad, as it seems like the upper left quadrant is 
partially working, the rest of the screen is just a bunch of 
loops.  It is also possible that the character generator ROM 
has gone bad.

Jon