Preferred way of substituting TFT for CRT Monitor?

js at js at
Mon Jan 18 14:39:38 CST 2016

On 1/18/2016 10:51 AM, 
Martin.Hepperle at wrote:

> this machine has a 98204B video board (intended to work with a 35721 monitor, which I don't have). I have not yet found the specs for its composite signal.
It's around 25khz.  The 98204B is 
normally used with the 35721 or 35731 
640x400 mono monitors.    The 98543A 
gives you RGB, but is also 640x400 (25khz).

> I find many $20 converters/scalers for composite to VGA on amazon or ebay but I am not sure whether such a thing would work for me. Obviously they seem to work for many computer games (SNES, Nintendo) and for some hobby computers like C64, Amiga etc. (e.g. "RCA Composite AV S-Video to VGA Converter Box").
None of them will work here.

> Next I see $50 devices like "Mini Composite RCA CVBS AV To HDMI Converter (Input: AV; Output: HDMI)" which may also be an option, but only seem to scale to a fixed HDMI resolution, which may be unsuitable for the HP-resolution of 512x400 (or 512x390?).
Won't work here.

> Finally I see $200 converters/scalers which are a bit expensive just for trying to see whether they work (e.g. "Atlona AT-AVS100 Composite/S-Video to Component/VGA Scaler").
Won't work here.

> I have also contacted Jon from the HP-Museum to see what their solution is.
You need a monitor (or converter) that 
supports 25khz.  Here's the extent of my 
own research:

25khz 640x400 SOG monitors

- NEC LCD1510+ (not tested)

- NEC LCD1810 (LA-1831JMW-1)
   Mac + PC -- fair performance, poor 
   HP 300/98543 -- works, but banded 
background cannot be completely
      faded to black (I got rid of my 
1810's for this reason).

- Viewsonic Vp150
   HP300/98543 -- works well, great 
background, colors only fair.

- Viewsonic VP181
   HP 300/98543 -- not perfect but can 
be adjusted ok.
     banded background *can* be faded to 

- J.

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