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Author Topic: 'Doubled up' picture & Flickering  (Read 2601 times)

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Nipedley

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'Doubled up' picture & Flickering
« on: October 15, 2017, 04:27:55 am »
Hey all

Having some issues with my Hantarex MTC9000, wonder if you can advise on what I should be looking at. What's been done so far:

Rejuvenator removed a short on the blue cathode
New flyback
Full capkit

It's hard to describe what's happening, but in the attached pic, you can see on the E in MAME that the pixels above what should be activated are also activated, so the E is doubled.  This happens over the whole screen, but that was the best example for me to show you. The pixels above however aren't fully 'on', they are slightly ghosted and flicker on/off. The doubled up effect combined with the flickering makes for a nasty headache!

You can also see on the text, there is a blue pixel activated to the bottom right of all the white text

What should I be looking at here? Would that be convergence related?

Many thanks for any advice!!

big10p

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Re: 'Doubled up' picture & Flickering
« Reply #1 on: October 16, 2017, 04:53:04 pm »
Is this running CRT_emudriver in an interlaced mode, by any chance? I have this issue on my MTC9000. Sorted it by going into ArcadeOSD and increasing the V total for interlaced modelines. Trial and error - just increase it a bit at a time, then hit the test key. If the display goes completely out of sync, you know you've gone too far, so back it down a bit. You should find a sweet spot where the image is rock solid (well, a very slight flicker because of the interlacing).

P.S. the issue with the blue pixels is convergence, and a separate issue.
« Last Edit: October 16, 2017, 05:03:47 pm by big10p »

Nipedley

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Re: 'Doubled up' picture & Flickering
« Reply #2 on: October 17, 2017, 02:59:16 am »
It is! Just what I needed, thank you  ;D

The blue pixels and slight left-right flicker were present with my arcade board as well. Is there any general guide for convergence adjustments or is it better to forget about it?

Not having the doubled up picture will help with my headache at least!!

Cheers

big10p

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Re: 'Doubled up' picture & Flickering
« Reply #3 on: October 17, 2017, 06:30:23 am »
I can't help with your arcade board - it just seems that some MTC9000 monitors (there are various versions of the chassis) don't handle interlacing too well. It's only thanks to CRT_emudriver and ArcadeOSD that we can tweak the modes to get the best results.

On one of my monitors (I have 3 MTC9000s), I still have the jiggling/flicker when I first turn it on, but it goes after the monitor has warmed up. Before adjusting yours, give it 10 mins or so to let it warm up.

Convergence is adjusted with the neck rings on the back of the tube. A bit of googling will probably find a guide, but care needs to be taken as obviously the monitor has to be turned on when adjusting the rings. However, some MTC9000 monitors use a Videocolor tube which doesn't have any rings - convergence and colour purity are set at the factory and can't be adjusted.

As you say your tube had a problem with the blue colour gun, you may just have to live with the convergence issue, although it doesn't look too bad in the pic.
« Last Edit: October 17, 2017, 06:31:59 am by big10p »

Nipedley

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Re: 'Doubled up' picture & Flickering
« Reply #4 on: October 18, 2017, 12:29:41 pm »
I had a play with arcade osd today, unfortunately the range on mine seems to be standard 523, lowest 480 and highest 620. Anything inbetween is identical (even and odd numbers looking slightly different), 480 or 620 both look great but scroll. If I amend the V HOLD control, they hold but then flicker like mad.

Anything else I can try? I know my MTC 9000 is an odd one as I've never found any pictures or schematics that match it.

To be fair, as it's only in the menus, I can live with it if needs be

big10p

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Re: 'Doubled up' picture & Flickering
« Reply #5 on: October 18, 2017, 02:00:18 pm »
Did you let the monitor warm up before trying the v total adjustments? Is your chassis the one with separate lever switches for RGB contrast?

I've done a search for when I was having this issue, and it seems I also replaced IC2 on the chassis. This is a TDA2595 chip which you can still buy on ebay. If your chassis is the same as mine, this should be socketed, so it's just a case of popping out the old one and fitting the new one. However, I was later told it's more likely that the pins of IC2 needed cleaning, or the socket needed replacing as there's a bad contact. If you're up for pursuing this route, I'd replace both to be on the safe side. The IC and sockets are cheap.
« Last Edit: October 18, 2017, 02:03:11 pm by big10p »

Nipedley

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Re: 'Doubled up' picture & Flickering
« Reply #6 on: October 21, 2017, 09:40:18 am »
I'd already replaced the TDA2595 a few years ago for a different issue, thankfully when I upgraded to the newest version of crt emudriver the V total adjustment worked - for me 503 was the magic number (down from 523)

Thanks for your help  ;D

big10p

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Re: 'Doubled up' picture & Flickering
« Reply #7 on: October 21, 2017, 10:23:51 am »
Ah yes, I should've mentioned you may need to decrease the v total, instead of increase. Like you say, there's a magic number that seems to work for most interlaced modes. Glad you got it sorted.  :)