Author Topic: RGB>LCD conversion -options advice needed  (Read 165 times)

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Offline digsys

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RGB>LCD conversion -options advice needed
« on: August 17, 2019, 12:44:24 pm »
Just finished a factory repair job - ripping out an old CRT (blew up) and replaced it with an LCD. Picked up a RGB > VGA converter board (the ones that the folks who convert old games machine use), sorted out a few issues, and all works acceptably well. Except for half of the last line of text is cut off (refer pix).
The customer doesn't mind, but I'm sort of a perfectionist :-) ... It's been 40+ yrs since I worked on CRTs, so got a bit rusty.
Wondering, how much effort to "fix" the problem - hardware? hack the software? (I think some gamers have posted their own "rewritten" code), or do I pay one of them to sort it out? Just looking for ideas -
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Offline PKTKS

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Re: RGB>LCD conversion -options advice needed
« Reply #1 on: August 17, 2019, 02:21:18 pm »
looks nice.

Unless you require that last thing...

I would try repositioning the blank pulse to avoid this
last noise things entering the buffer for conversion

e.g. put the blank pulse a bit earlier to suppress that noise.



 

Offline digsys

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Re: RGB>LCD conversion -options advice needed
« Reply #2 on: August 17, 2019, 11:30:03 pm »
Quote from: PKTKS
Unless you require that last thing... .. e.g. put the blank pulse a bit earlier to suppress that noise
Thanks for the reply. Well, that's my quandary - a half missing line wouldn't be ideal for the operator, and they could live with the noise option. Wasn't sure if it easier to fix it going the "software hack" method, or a much longer hardware fix. It can hold for now, but with 2 more possible to fix, it was annoying me :-)
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Offline Rasz

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Re: RGB>LCD conversion -options advice needed
« Reply #3 on: August 18, 2019, 05:20:17 am »
did you press AUTO on the gbs? and on the lcd monitor?
you can try clamp options in Geometry menu

then of course is the nuclear option, bypassing buildin microcontroller, can be done with $2 esp8266
https://shmups.system11.org/viewtopic.php?f=6&t=52172

https://github.com/ramapcsx2/gbs-control
https://github.com/ramapcsx2/gbs-control/wiki/Build-the-Hardware




all of this is overkill, because as you and the owner of machine already stated last line is meaningless
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Offline digsys

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Re: RGB>LCD conversion -options advice needed
« Reply #4 on: August 18, 2019, 08:46:33 am »
Quote from: Rasz
did you press AUTO on the gbs? and on the lcd monitor? you can try clamp options in Geometry menu ...
Yup, fiddled with pretty much every setting, I can get either the top line or bottom line perfect, but not both - one gets cut in half > 2/3. If I shrink V further, all I get is raster / garbage on the last line and rest of screen.
I haven't seen those particular links, but did find other users that had made "hackable" code, so another possible option. Thanks
Quote from: Rasz
... all of this is overkill, because as you and the owner of machine already stated last line is meaningless
Well, I hate leaving jobs nearly ok, and I think the owner just wanted his machine back asap. I will sort it out, was just working out what each path involved.
Hello <tap> <tap> .. is this thing on?
 


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