I recently set up my Amstrad CTM 644 RGB Monitor again, to use with a couple of games consoles. Since I've had it I've never gotten around to tweaking the picture settings as I didn't fancy having to open it up to do so as I don't like messing with CRT monitors usually. But today I finally decided to just go for it and opened it up. It sure was dusty inside -
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Firstly the image was too dark, even with the contrast control at the side set to max. A few adjustments of the sub bright & brightness pots and I got it looking much better. Also applied some contact cleaner to the contrast pot, so that it no longer flickers when used.
Next the colours were slightly off, with dull almost invisible reds. Using the 240p Test Suite on my Mega Drive, I brough up the colour test patterns and then tweaked the red pot slightly to increase the vibrance. At first the picture became a bit too reddish, so I tweaked it back down slightly and got a good balance. Now the reds are bright and visible and the overall colour balance is much improved.
I could probably spend more time and tweak it further, but to avoid pushing my luck I think I'll just quit while I'm ahead. It's not perfect, but it'll certainly do. I have it placed next to a circa-2000s era CRT TV and when they're both switched on you can clearly see the Amstrad's deficiencies in comparison, but it does it's job.
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Also yesterday I received an Amstrad GX4000 games console "Untested" from eBay. Of course "Untested" here = broken.
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The Player 1 controller port is missing all the fire button pins for a start - not shown in the pictures.
Secondly after opening it up and powering it on, 1 of the RAM chips was burning hot. Even without a game to test with at present, I'm 100% sure that DRAM chip is dead, so I removed it. I've got replacement 464 DRAM chips on the way this week. I've just removed the 1 chip for now, if it still doesn't work then I'll remove the other too.
I tested the voltages and the regulator seems fine, everything that should be getting 5V seems to be, so hopefully it's just a bad RAM chip and a broken controller port.
I don't have a hot air station to properly remove & replace the controller port , so I might just bodge it by soldering in some jumper wires and using a 9-pin adapter with jumper breakout cables.
I do have a fully working Amstrad GX4000 on the way, along with a copy of the pack-in game Burnin' Rubber, so getting this console up and running is mostly just for fun at this point.