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TECH: Tektronix 7633 frame and accs....

Hi all!

I just picked up a SUPERB condition Tek 7633 storage frame with a timebase and a few amps.

It's all working perfectly, but I've got one issue, it may be me, maybe the scope has a small problem, or maybe they're like this......

When the intensity of the display is turned up to 9/10, it is fine, reasonably bright - not as bright as a more modern scope, but I'll accept that from a 30 year old workhorse - however, when I turn it up that last 1/10, it goes out of focus. Are they meant to do that to protect the tube or something? Or is it because it's an old persistance analog storage tube that maybe it's a quirk of the design?

Or do I have a fault?

Any advice is appreciated.

Yours, Mark.

Reply to
Mark (UK)
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"Mark (UK)" wrote in news:ccv4sr$oj9$ snipped-for-privacy@sparta.btinternet.com:

It sounds reasonable.The older a CRT gets,the weaker the cathode gets,and it takes more beam current to get a trace,but it emits from a wider cathode area,defocusing the beam.Those storage tubes also use a mesh lens after the horiz deflection plates that make for a less sharp beam.

BTW,you can tell the approximate age of your scope by checking date codes on various items;the format is for example;4380,would be week 43,year

1980.Don't just read one IC and figure that's it,look at some big items like the power transformer,etc.If you get one PCB with date codes not consistent with the other PCBs and power xfmr,then boards have been swapped/replaced. 
--
Jim Yanik
jyanik-at-kua.net
Reply to
Jim Yanik

Hi!

Thanks for that reply, I didn't expect supersharpness, but for the age of it, it's very good.

The PCBs inside the frame have (c)1973 on them - would that be the year it was designed or the year it was made?

It looks like everything is original, as it all matches for stickers inside the plugins.

Yours, Mark.

Jim Yanik wrote:

Reply to
Mark (UK)

"Mark (UK)" wrote in news:ccvr5b$jn6$ snipped-for-privacy@sparta.btinternet.com:

Look for date codes on components,not the PCB date,that's the date the PCB was designed,IIRC.

--
Jim Yanik
jyanik-at-kua.net
Reply to
Jim Yanik

..snipp

Proceed as Jim has proposed, the date on the pc boards seems to be all the same on these units, so it has no meaning for the age of your particular scope.

A manual of the similar 7623 scope can be downloaded free of charge from

formatting link
tech. manual section. Do a search for tektronix on this website.

hth, Andreas

Reply to
TekMan

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