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Main => Monitor/Video Forum => Topic started by: srarcade on May 19, 2009, 01:13:53 am

Title: U2000 Contrast Problem
Post by: srarcade on May 19, 2009, 01:13:53 am

I picked up a Sega STV cab that has a standard res U2000 with a WG tube. The picture is very faded, even with the contrast on full. First I adjusted the screen voltage on the flyback, no help really. So then I re-capped the chassis, and that didn't do much of anything either. The picture quality is sharp and clear as can be, just really faded out. I've heard earlier tubes on these are just plain bad, but I figured the WG would be half way decent. I suspect a faulty component someplace. Any ideas?

Thanks!

Title: Re: U2000 Contrast Problem
Post by: SirPeale on May 19, 2009, 05:23:42 am

For giggles pull one end of R811 and test it, it may have gone open.

Title: Re: U2000 Contrast Problem
Post by: srarcade on May 19, 2009, 09:06:15 am

Thanks I'll give that a go this evening.  :cheers:

Title: Re: U2000 Contrast Problem
Post by: srarcade on October 01, 2009, 04:46:44 pm

Finally got around to addressing this cab.

Yes, R811 was in fact bad! Did not produce any reading upon testing with a multimeter, even after pulling it completely. Replaced it and now the contrast is much much better, problem solved.. well mostly-  :D

Now a new problem, now that my contrast has returned I can obviously see my red is only 1/3 as bright as it should be. Fiddling with the red drive and red bias doesn't seem to help, not sure what the deal is, must keep researching.

Thanks!

Title: Re: U2000 Contrast Problem
Post by: mvsfan on October 01, 2009, 06:28:59 pm

Quote from: srarcade on October 01, 2009, 04:46:44 pm

Finally got around to addressing this cab.

Yes, R811 was in fact bad! Did not produce any reading upon testing with a multimeter, even after pulling it completely. Replaced it and now the contrast is much much better, problem solved.. well mostly-  :D

Now a new problem, now that my contrast has returned I can obviously see my red is only 1/3 as bright as it should be. Fiddling with the red drive and red bias doesn't seem to help, not sure what the deal is, must keep researching.

Thanks!

Hmm. I just had a u2000 chassis professionally gone through and everything was fixed except the fade.

I was leaning towards having a bad picture tube. so i have to pry up one leg of R811 and check it  and this ought to solve the problem I really do hope its bad. you dont know how much this post just helped me. ill let you know how it works out.

Title: Re: U2000 Contrast Problem
Post by: mvsfan on October 01, 2009, 06:30:42 pm

Sometimes im so glad im a procrastinator. Ive put off and put off ordering a new tube.

Title: Re: U2000 Contrast Problem
Post by: SirPeale on October 01, 2009, 07:39:03 pm

Quote from: mvsfan on October 01, 2009, 06:30:42 pm

Sometimes im so glad im a procrastinator. Ive put off and put off ordering a new tube.

Yes, please post and say if that was your problem or not.

RE: lack of red, your tube may need to be hooked to a rejuvenator. 

Title: Re: U2000 Contrast Problem
Post by: srarcade on October 01, 2009, 10:59:13 pm

Thanks for the tip. I don't have a rejuvenator.. maybe its time to get one I have been working on enough monitors this year I think I owe it to myself. I think the red may also be related to a component on the neck card, was getting some flicker of red on/off when tuning the pots. I have also been following the WG troubleshooting pdf http://www.wellsgardner.com/pdf/Repair/U2000_25_27_inch.pdf (http://www.wellsgardner.com/pdf/Repair/U2000_25_27_inch.pdf) which points out a few other items it could be so I'll give those a check too.

Was playing with it again tonight, got the levels all correct but also noticing a bit of horz lines, very faint but I'll say again, R811 definitely made a vast improvement over before. Once the red comes back it should look really tip top.