exxos's Atari, Amiga & retro forum

alexh wrote: 13 Mar 2024 11:56 I only own a C128D (that has not seen the light of day for a long time) but out of curiosity why did you choose "LumaFix128"?

I have been considering an luma pickup board VICdizer128 + RGBTOHDMI?

https://www.tindie.com/products/c0pperd ... -ii-dizer/
https://www.tindie.com/products/c0pperd ... -lumacode/
https://www.tindie.com/products/c0pperd ... rod_search

It's a tad expensive at $100 for the full kit but the RGB2HDMI box is reusable across multiple computers C64/128/Atari 800/Apple II/Ti99/MSX/CoCo etc. they just need individual pickup boards.

Only because it was one of the only versions that I could find in stock anywhere at the time I was looking. This didn't come up in my searches.

Agree that the RGB2HDMI is useful, and I would like to get one, but it's not a particularly high priority right now.

OK, so I have been playing with the Lumafix128 and I'm a bit underwhelmed tbh. I can't say I wasn't warned to be fair though...

First pic is before:


And this pic is after:


There is a definite improvement, but the colour is somewhat washed out and adjusting that specific pot too far does have the effect of giving a chequerboard effect when the colour comes back. I think part of the problem is the range of adjustment on the pots is a bit far.It's supposed to be 12 turns end to end, but I think it's more like 12 turns to the middle, so 24 end to end, and the 'audible click' that is supposed to happen at the end of the travel is there on some pots and not on others, so the only way to check is to wind the pots all one way and measure with an ohmmeter.

Add to that the signals can be inverted with a set of switches in the bottom and that just confuses things.

I think ideally I do need a CRT to tweak it properly since I'm currently running composite out via a Retrotink to HDMI.

I also discovered something interesting in C64 mode too.

If I hold down the left Commodore button on boot to go to C64 mode, I get a pale display and some banding, but if I type GO64 from the C128 prompt I get a lovely clean clear C64 display. It's a bit odd.

If anything I preferred the "before" as it was crisper.

I just took the LumaFix64 out as it just seemed to make things worse.

P.S. I think we just have to remember that these old machines have their quirks. The C128 VIC has jail bars, as does the Spectrum ULA. We just have to live with them. It's not helped by the discretisation by the A to D in the display is going to make things look worse too.

stephen_usher wrote: 17 Mar 2024 18:14 If anything I preferred the "before" as it was crisper.

I just took the LumaFix64 out as it just seemed to make things worse.

I don't entirely disagree, but I'm not done yet. Will spend a bit more time on it I think and I'll see if I can improve it, but I do think I need to see if I can get something like a 1084 or 1084s. I think the 1084s also supports RGBi which would be good for the 2nd video/80 column output.

Keep meaning to look at RGB2HDMI as well.

My C128D is connected to a VGA monitor by that Adaptor I pointed you to RJ and using that it took ages to get the Lumafix right, coming back to it on a couple of different occasions.

One interesting fact is that the Open128 board that's now in my C128D has a really good picture without the Lumafix. I"'ll have to review the two circuits and see what they changed.

I also remember not using the correct cap values, so might have corrected it by accident.

PhilC wrote: 17 Mar 2024 18:48 My C128D is connected to a VGA monitor by that Adaptor I pointed you to RJ and using that it took ages to get the Lumafix right, coming back to it on a couple of different occasions.

One interesting fact is that the Open128 board that's now in my C128D has a really good picture without the Lumafix. I"ll have to review the two circuits and see what they changed.

I also remember not using the correct cap values, so might have corrected it by accident.

Nice to know it worked for you. Which adaptor was that, I bought a few lately :dizzy:

It was this one @rubber_jonnie

https://www.amazon.co.uk/dp/B081SBNJ58/ ... F9kZXRhaWw

I use it with S_Video

No picture ?

PhilC wrote: 18 Mar 2024 09:28 It was this one @rubber_jonnie



I use it with S_Video

What @HigashiJun said - no picture.

I forgot to add the /url bit