Re: Update on 2465

Siggi
 

On Wed, 4 Jan 2017 at 06:45 tatumj1@... [TekScopes] <
TekScopes@...> wrote:



Good morning Siggi. It seems that the symptoms on this scope have
constantly changed from the time I turned it on. At first it only flashed a
few panel LEDs. Now, after warm up, seems to work close to normally, tend
now to think it may be the caps, As it gradually moves closer to working
properly, the distorted trace moves toward normal. I do think someone has
changed some of the caps. I don't think Tektronix installed the power
supply caps standing off the board on long leads more than 1/4 inch above
the board surface.

Intermittent trouble is the worst, I hope you get this sorted.
I am printing out all your responses to use as trouble shooting guide. I
appreciate your help very much.

My pleasure - please let us know what you find.
This has nothing to do with the problem we have been chasing, but I
noticed that the focus control only brings the screen into focus near the
full counter clockwise position of the pot. I am looking in the manual at
the focus control circuit for an adjustment for this.

There is a CRT adjustment procedure in the service manual. Section 5
starts with power supplies, then goes on to the CRT.
The CRT adjustment procedure will have a bunch of interacting adjustments -
it could be e.g. that the geometry pot has drifted. It may also help for a
scope that's been stored for a long time, to let the CRT "bake" for a few
hours to days with a low-intensity beam. See e.g. <
http://www.eevblog.com/forum/testgear/dim-oscilloscope-screen/msg554039/#msg554039
.
Also, you shouldn't expect the 2465 to match your 454A for trace clarity or
dot size, as the 2465's CRT has an expansion mesh.

I've only been through the CRT adjustment for my 2467, which has a very
different CRT, and it's been a couple of years, so I can't help much there.

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