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Author Topic: MTC9000 red color too dominant  (Read 514 times)

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sollima

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MTC9000 red color too dominant
« on: August 02, 2019, 09:45:34 am »
Hello,

I have a MTC9000 that a gave a complete capkit. Even the poly are replaced.

I had some brightness issue, that it was a bit dimm. I replaced R90, R80, RV7, R216 and all the pods on the neckcard. It helped a bit. (I replaced R216 with a 1 Ohm resistor that was in the manual because it was higher than 1 Ohm. I saw a post in which Grantspain stated to use a 0,33 Ohm
Side question: would that give more brightness? Or probably damage the heaters?
Reply #6)


If I turn on the monitor and try to set the brightness and colors I can adjust them all. They are all responsive to the gain and cut-off (the others more than red), and I have a little bit of brightness control. The problem is my red. It responds the least of them all and when I dial it back to its minimum it still stays too bright/strong.

When I dial the G2 (flyback) down the red ‘bleed through’ comes down. But the brightness of the othe colors come down too. So the ‘sweet spot’ of brightness and contrast dissapears and the picture becomes somewhat too dimm.

I wish the red would ‘stay in line’ with the green and blue.

Could this problem problably be with the transistors on the neckcard? Or should I be looking elsewhere?

Thank you for your help in advance

grantspain

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Re: MTC9000 red color too dominant
« Reply #1 on: August 02, 2019, 09:49:21 am »
maybe a leaky diode d4 or leaky tr201
do you have contrast pot or switch array?

sollima

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MTC9000 red color too dominant
« Reply #2 on: August 02, 2019, 10:03:45 am »
maybe a leaky diode d4 or leaky tr201
do you have contrast pot or switch array?

Thank you for your reply. I will measure and probably replace the transistor and diode.

I think I have the switch array. (three ‘levers’ with three settings.)

grantspain

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Re: MTC9000 red color too dominant
« Reply #3 on: August 02, 2019, 03:31:19 pm »
those chassis with the contrast switches can cause your exact issue, use some switch cleaner and see if it helps

sollima

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MTC9000 red color too dominant
« Reply #4 on: August 02, 2019, 04:14:48 pm »
those chassis with the contrast switches can cause your exact issue, use some switch cleaner and see if it helps

Thank you again for the tip. I will try that too.

sollima

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Re: MTC9000 red color too dominant
« Reply #5 on: August 09, 2019, 03:58:32 am »
I used contactspray on the contrast switches
I replaced transistors TR201 + TR202  + TR203 on the neckcard
I replaced diodes D4 + D1 + D2

The dominance of red issue has sadly not dissapeared. The colors on the otherhand I think look good. But maybe I don’t have the right eye for it.





I use Pi2Jamma for my gamesetup. Maybe it’s an artifact produced by the vga666 module and not a chassis fault? I don’t know.
Or could it be a resistor failing in the red circuit?

Thanks for the help so far . Much appreciated.

grantspain

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Re: MTC9000 red color too dominant
« Reply #6 on: August 09, 2019, 04:39:16 am »
only way to prove it is try a jamma game board or a signal generator