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Author Topic: Fixing a video board over on vcfed  (Read 4808 times)

stepleton

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Fixing a video board over on vcfed
« on: September 15, 2023, 01:14:50 pm »

An interesting and technically detailed discussion around fixing a video board is taking place on vcfed:

https://forum.vcfed.org/index.php?threads/lisa-video-fault.1244688/

When I have a moment, I'll take the time to sit down with a schematic and learn something.
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sigma7

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Re: Fixing a video board over on vcfed
« Reply #1 on: September 15, 2023, 05:43:02 pm »

An interesting and technically detailed discussion around fixing a video board ...

Thanks for the tip!

Hugo mentions some designs having a variable inductor as a coarse width adjustment...

The earlier versions of the video board included the variable inductor L3, which was adjustable through the small hole in the back of the card cage area. If you have one of these video boards, you'll find that adjusting L3 doesn't really do anything (at least it didn't seem to have an effect for me; if you do want to try adjusting it, use a non-metallic tool).

L3 was deleted with rev. F

If you ship one of these boards, L3 being tall and weak is prone to breaking loose; if so, you can just remove it.
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sigma7

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Re: Fixing a video board over on vcfed
« Reply #2 on: September 15, 2023, 06:08:49 pm »

When I have a moment, I'll take the time to sit down with a schematic and learn something.

The schematic linked in the vcfed post is an older version (E), whereas the final version is J: Lisa Video Board Rev J Schematic.
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