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SC 503 Enhance/Integrate removed on later units

 

The Enhance/Integrate knob + corresponding electronic components (Storage schematic 10) have been removed on later units, SN B040000 and higher. The remaining circuit + CRT was mainly unchanged.
Why has this been done? Did it stress the CRT too much?
?
Stefan
 

Hi Stefan,

I've actually both a SN B040000 and up newer version, and an older one.
They're both non-working and restauration projects.
However, I've taken a quick look already, and if I remember correctly, the PCB are actually same.
But with the enhance/integrate switch/potentiometer combo not installed (holes are there!).?Otherwise components seem same.
I can have closer look if you want.

BTW, do you have the newer version's manual? Tekwiki only has the older one.

Best regards,
 

Ke-Fong Lin,
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please take a closer look, if some components are not installed in the newer one. (Should be according to newer manual.) The F&I BD is on the left side. I've added a screenshot schematic 10 for B040000-up:
/g/TekScopes2/album?id=280676
The newer manual only states 50cm/s stored writing speed. Old version was 250!
The newer manual can be obtained from Artek Media.
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Stefan
 

Hi Stefan,

Look at the photo directory, I've added a screenshot of the older schematic along with photos.
For my restauration, I'll eventually have to buy the SN B040000 manual from Artek Media, but right now I only have access to older one from tekwiki.

The newer version has green PCB and missing components. So my guess the PCB is basically the same, minus the components of course.
Note that A20 board (focus & intensity) has already 4 revisions? (part 670-5369-0[0-3]) for the older version. It would be interesting to look at the part number of the newer version.

Also, may be they use a different tube (V500), on the older one, this is part 154-0812-00.

Best regards,
 

Hi Ke-Fong Lin,
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nice photos. The newer A20 BD changed to Rev 4 (670-5369-04). The CRT is still the same.
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Stefan
 

Hi Stefan,

Kinda strange they updated the part number of the PCB, yet they have unpopulated parts.
Maybe they changed "technology" in the manufacturing of PCBs and made only the minor changes needed for that.

As for the CRT, if it's exactly the same part, I guess there are basically the same as the ones before.
And in some way, you should be able to? "retrofit" a newer S/N B040000 with the integrate/enhance functionality by populating the components.


Best regards,
 

Hi Ke-Fong Lin,
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for me it's logical to change the PCB rev: something has changed.
Maybe the board material has changed too, but I think the point is that the Enhance/Integrate functionality has been removed. (But why?*) Layout changes cost money ¨C they wanted smallest effort.
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And yes, I think your "retrofit" idea could be possible. Your photos show the same boards, one just less populated.
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*Maybe some parts became too expensive for too low sales. One unit was $2850 in 1981 and $3440 in 1984 w/o Enhance/Integrate.
Maybe Enhance/Integrate was removed, because buyers should buy something else/new.
Just guessing.
?
Stefan

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