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Macintosh LC video output to modern monitor?


Veteran Member
Apr 30, 2015
Austin, Texas
I know but LC475 works with switchable adapter!
So there must be something else...

"but apples and oranges!"

You're comparing two entirely different machine architectures. If the LC475 works at 512x384 on an LCD monitor, I would gather that the horizontal frequency is higher than 24 kHz.

I have, they're junk. There's a whole market of those conversion boards and an infinite number of clones of clones of clones. You never know what you're going to get, you just know it will be trouble. The stock firmware on those units leaves A LOT to be desired. The arcade community has done a bunch of hacks to make that conversion board work properly, because many of the things the people that sell those boards claim it does, it in fact does not do, or even close to.

The thing I bought one of those boards for was RGB to VGA, it didn't work. You would get a picture, but after about 10-15 seconds, the output would get unstable and desync repeatedly. No amount of bodges or workarounds would get it to work. In the end, I found a cheaper method of replacing the RGB encoder chip with a slightly different model that had Y/C out to make an S-Video circuit. 95% of the quality at 25% of the cost.


Experienced Member
Jan 4, 2014
I know, I rechecked this again. It's about 24.5Khz/60hz as you said.

I have about 10 different DB15/VGA Adapters. I checked all switchable before. Now I checked three that are not switchable.

1. Output 640x480 works with nearly all TFT's I have
2. Output 640x480 works with only some of my TFT's
3. Output perhaps? 512x384 works with none of my TFT's
3.a. => no picture at all with or without error message
3.b. => switches the TFT to 720x400 only a white screen nothing else
3.c. => switches the TFT to 640x400 only a white screen nothing else

I have one adapter that is switchable and this works on LC475 with Nec 71vm, but that is a very fast machine and it also does not support system6 with single-finder, so no real solution for me. I think about buying a high-resoultion-nubus-card for my Mac II. The high-resolution-card also supports very low resolution that the "normal" Toby card can not. But these cards are very hard to find.
I had tested these and Line1 is interesting for the 10.DipSwitch-Adapters.
I cant reproduce the LC475 working with 512x as it did a longer time ago.

So I will stay with 640x480 on that LC.


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