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Old 11th Jan 2020, 12:03 pm   #1
line sync
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Default Setting up an RGB monitor.

Towards the end of last year I rebuilt a hanterex arcade games monitor and want to set it up on the bench before fitting back into the cabinet.
Now these monitors are RGB composite sync input and you can't just plug a pattern generator in.

In the old days the guys who repaired these had pattern gens made for the job but it appears you can't buy them anymore.

Anyone got any ideas .

Robin
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Old 11th Jan 2020, 12:22 pm   #2
barrymagrec
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Default Re: setting up an RGB monitor

You can set most computers to the appropriate line and frame rate and use the VGA output to drive the separate RGB channels. there are plenty of test patterns available on the internet.
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Old 11th Jan 2020, 12:33 pm   #3
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Default Re: setting up an RGB monitor

What scan rate is the monitor supposed to run at?

If the line rate is 15kHz, then you probably could drive it from a DVD player (which all output RGB + CSync). You will need a region 2 disc if the field rate is 50Hz, or a multi-region player and a region 1 disc if 60Hz.
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Old 11th Jan 2020, 2:10 pm   #4
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Default Re: Setting up an RGB monitor.

Hi,
I think the Black Star Orion pattern generator does have a 9 pin d connector that will give a similar signal. Of course it is only worth getting one of these if you are going to be doing lots of monitor repairs. But it will only work only if the Hantarex monitor is a 15 khz variety.
if is is a higher frequency monitor then I'm not sure what to suggest. At one point when I worked for a company servicing arcade machines one of the people in the logic board repair department designed a unit using eproms and d to a converters to give the 25khz video signal needed.
of course they may be better ways of doing it now...
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Old 11th Jan 2020, 2:46 pm   #5
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Default Re: Setting up an RGB monitor.

Thank you all for your reply`s so far.
The monitor in question is 15khz.
I`m not surprised this can be done using a computer but I`m not very confident doing it that way but i like Julie`s idea of using a dvd player and I`ve got some old scart Leeds I could cut up.

Robin
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Old 11th Jan 2020, 2:53 pm   #6
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Default Re: Setting up an RGB monitor.

Hi,
it is possible that the RGB signal from the dvd player might not be quite enough to drive the monitor ( sorry my Memory isn't as clear as I would like it to be ).
so you might get a darker picture than you expect.
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Old 11th Jan 2020, 3:49 pm   #7
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Default Re: Setting up an RGB monitor.

is the monitor analogue or TTL? A dvd player will output RGB at analogue levels but I'd say an arcade game is more likely to be TTL (digital).

Most PCs will not be able to supply 15khz unless you get a multi-frequency graphics card, you'd have to find one and the appropriate driver and programme. I have an ATI vip card that will do it but it needs an ISA slot.

A 15khz test pattern generator won't fetch much second hand so it might be easier to pick one up.

If this sounds like a faff, you'll probably get away with setting it up by trial and error on the arcade game itself. It's not as though you need perfect flesh tones or tint-free reproduction of an old black and white film.
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Old 11th Jan 2020, 6:13 pm   #8
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Default Re: Setting up an RGB monitor.

Hi Kevin
Just reading the spec for this monitor and it says TTL input.

Robin
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Old 11th Jan 2020, 7:00 pm   #9
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Default Re: Setting up an RGB monitor.

there's one here

https://www.cashconverters.co.uk/sho...nerator/648809
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Old 11th Jan 2020, 7:58 pm   #10
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Default Re: Setting up an RGB monitor.

Hi Kevin
Thanks for that but it says its no longer available.
I was very tempted until I read that.

Robin
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Old 11th Jan 2020, 8:59 pm   #11
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Default Re: Setting up an RGB monitor.

I don't suppose you have a BBC micro around the workshop? The (6 pin DIN) RGB socket on that machine would appear to be ideal for testing this monitor.
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Old 11th Jan 2020, 9:06 pm   #12
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Default Re: Setting up an RGB monitor.

Hi Tony
unfortunately I don't.
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Old 11th Jan 2020, 11:18 pm   #13
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Default Re: Setting up an RGB monitor.

You could use (three quarters of) an LM2901 quad comparator IC to switch at some level, with a 4.7k pull-up resistor from each output to +5V and the inverting inputs fed together from a 10k pot across the 5V supply, with a 22k resistor in series with the "top" end to make use of more of the range of the pot.

You might need the fourth comparator to level-shift or invert the sync. A quick breadboard lash-up should be fine.
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Old 12th Jan 2020, 3:43 pm   #14
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Default Re: Setting up an RGB monitor.

'Classic' arcade monitors (I assume this one is a Hantarex MTC900 or MTC9000 or similar) are almost always analogue RGB input, 15kHz horizontal scan rate, composite sync, so they are pretty much compatible with RGB SCART from DVD players or set top boxes. The catch is that they don't have sync separators, so the usual SCART sync signal (which is actually composite video) doesn't work. The easiest fix may be to wire up something like an LM1881 sync separator chip (plus the, I think, one resistor and capacitor it needs - check the data sheet) and then the monitor should work quite happily from any RGB SCART output. It will probably need the vertical hold adjusting because most arcade games are 60Hz rather than 50Hz of TV in Europe.

Alternatively, find a friend who has a Commodore Amiga, Atari ST or Acorn Archimedes, or a collection of arcade PCBs!

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