Re: 454 screen brightness issues?


Jack Ohme
 

Update:
Upon resistance testing the cathode and grid, it seems to want to conduct
one way (in negative resistance, according to my meter), and not conduct at
all the other...
So perhaps the grid is not broken after all? Although this was with the
whole socket connected, so for all I know I could just be reading a diode
in the circuit, although the -10Mohm resistance would be odd for that.

On Mon, Jan 6, 2020 at 8:10 AM Chuck Harris <cfharris@...> wrote:

I saw that once in a 2456B's CRT. An internal weld between
a strap and an element broke, leaving an open circuit on
the CRT's intensity (control) grid .

The symptom was the intensity started out low, readout seemed
fine, and the beam could be moved with the intensity control,
but the beam kept getting brighter and brighter.

-Chuck Harris

Mlynch001 wrote:
I'm
wondering if maybe the grid assembly was knocked loose during shipping
maybe? I'm not intimately familiar with the CRT construction, so maybe
someone more well-acquainted with Tek's CRTs could give me some idea of
what may be going on...
While fixing my newest 465 I recall seeing a post where a 465 had a
similar problem. The OP found an internally disconnected Grid pin. Here
is the post.

https://groups.io/g/TekScopes/topic/tek_465_intensity_problem/7656664


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