I swapped my chassis for a tri-sync, but .....

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ckong
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I swapped my chassis for a tri-sync, but .....

Post by ckong » October 29th, 2008, 11:55 am

I have some problems with my rodotron 666A-29 tri-sync chassis, which I put in my New Astro city Cab with Toshiba A68KJU96X monitor. I will post my 'how to swap a chassis in a New Astro city' complete with pictures later, but I first want to clear the problems I have. There are several, but I'll start with these:

Setup: New Astro City with a brandnew Rodotron 666A-29 Chassis, directly connected via VGA to a Mame PC, ArcadeVGA (old model with 3 outputs). The chassis gets it power via a 220V/110V step down converter (I know the chassis can handle both, but I don't want to replace the original plug with flat pins and I don't have a pin-converter). I checked and double checked the earth connection of the monitor frame and chassis up to the wall socket, which is as it should be.

The problems have to do with distortion and vertical alingment.

Problem 1 (see picture below): There is a lot of distortion on top of the picture and on the bottom side of the picture (The pink lines should be straight and solid). The distortions run from left to right across the whole screen. The distortion at the top becomes even more when I adjust the v.pos pot so that the image positions higher. The whole top part of the image gets distorted.

Image

Problem 2 (see picture below): I can't move the bottom of the image downwards. When I turn the v.size pot I can position the top of the inage at the top of the screen. however, the bottom of the image won't move downwards, leaving a gap of approximately 3 cm from the bottom of the screen. Also strange is that when I adjust the size of the image (try to make it larger), the text field on the bottom of the image merges with the bottom pink line, although its location should be as shown in picture 1.

Image

And finally, a picture of my rodotron 666A-29 chassis (perhaps usefull to help me finding the problem):

Image

Both problems occur also when I connect a Dreamcast via VGA to the monitor, so I guess it has nothing to do with the (old) ArcadeVGA card. I probably have to adjust some pots on the chassis, but I have no clue which one (unfortunately the chassis came with little to no documentation).

What could be the cause of this?

Another, simple question: There is a video input impedance switch (75 Ohm, 1K OHM) on the breakout PCB. Where is it for?

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Re: I swapped my chassis for a tri-sync, but .....

Post by kernow » October 29th, 2008, 1:36 pm

Thats the video impedence switch (duh, I see you mentioned that hehe), for 15k it should be on 1k, for 31k, 75ohm.

Just changes the brightness and thickness of scanlines, wouldn't affect the picture in any other way though. So you can eliminate that from causing the problem, I'm pretty sure.
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Jason
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Re: I swapped my chassis for a tri-sync, but .....

Post by Jason » October 29th, 2008, 1:44 pm

I got the same chassis on my new Nieman Display Tri-Res 29 inch...

But the Tube that Nieman uses is a Phillips....

The issue that you are having has to do with the B+ for the 31k(high-res), mine had it when I was using 15k(low-res).

Adjust the pot on the chassis clockwise it is located on the back of the chassis(refering to your pic) there are 3 blue pots almost right in a row, 31k should be the one closest to you in that row, which is the first one going up the row, crank that sucker almost all the way up and it should get rid of the overlapping that you are seeing.

You may have to do it for your 15k too, but im not positive.

Quote:
Another, simple question: There is a video input impedance switch (75 Ohm, 1K OHM) on the breakout PCB. Where is it for?

75 Ohm is High-Res and 1k Ohm is Low-Res, basically it ups the brightness and contrast for your high-res stuff :)

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ckong
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Re: I swapped my chassis for a tri-sync, but .....

Post by ckong » October 29th, 2008, 2:39 pm

Jason wrote: Adjust the pot on the chassis clockwise it is located on the back of the chassis(refering to your pic) there are 3 blue pots almost right in a row, 31k should be the one closest to you in that row, which is the first one going up the row, crank that sucker almost all the way up and it should get rid of the overlapping that you are seeing.
Thanks, I did that, in small steps clockwise and anti-clockwise. But unfortunately it didn't solve the problem. I saw some changes, but these were not improvements. please see the picture as another example of my problems (soul caliber - dreamcast). Notice the terrible distortion and the remaining space at the bottom of the screen:

Image

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Re: I swapped my chassis for a tri-sync, but .....

Post by Jason » October 29th, 2008, 2:44 pm

maybe try cranking it down....

like i said I had this issue with my 15k not 31k, but I did call Neiman to confirm what was doing this and he did say it was the B+ so...

there is another pot that is for 31k too its in a dangerous spot which is right behind the Coil black thing that runs the red wire up to the tube itself, if you can reach that try and adjust it?

I have a schematic off all the pots, I can upload it tonigh after i get home from work.

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Re: I swapped my chassis for a tri-sync, but .....

Post by Jason » October 29th, 2008, 3:00 pm

If none of those work you can always send him an email, with your issue...

Rick@Niemandisplays.com

Like i said he uses those chassis for tri-res so I think he knows them inside and out.

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Re: I swapped my chassis for a tri-sync, but .....

Post by ckong » October 29th, 2008, 3:14 pm

Jason wrote:
I have a schematic off all the pots, I can upload it tonigh after i get home from work.
Thanks, would be nice

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Re: I swapped my chassis for a tri-sync, but .....

Post by grantspain » October 29th, 2008, 6:25 pm

ooo,don't like the look of that.what happens when you adjust the vertical size?

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Re: I swapped my chassis for a tri-sync, but .....

Post by ckong » October 29th, 2008, 7:11 pm

grantspain wrote:ooo,don't like the look of that.what happens when you adjust the vertical size?
Me neither. I made 2 new pictures. The first one with the vertical size pot set in the middle (not the picture, but the pot), and with the second one I adjusted the vertical size pot until the image hits the top of the screen.

Image

Image

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Re: I swapped my chassis for a tri-sync, but .....

Post by grantspain » October 29th, 2008, 7:41 pm

looks like you have a fault on that chassis,exchange it

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Re: I swapped my chassis for a tri-sync, but .....

Post by ckong » October 29th, 2008, 8:22 pm

grantspain wrote:looks like you have a fault on that chassis,exchange it
I feared that already. What a bummer! I only recently bought it at Excellentcom, and I will contact them about this. Let's cross fingers.

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Re: I swapped my chassis for a tri-sync, but .....

Post by grantspain » October 29th, 2008, 8:38 pm

those chassis have a very poor quality control and are very prone to dry solder joints,my bet is that there is an unsoldered component on the vertical output section-either aroung the tda 1745 or from the flyback

you should carefully inspect the chassis for any suspect solder joints

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Re: I swapped my chassis for a tri-sync, but .....

Post by Jason » October 29th, 2008, 9:29 pm

here you go buddy....
Image

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Re: I swapped my chassis for a tri-sync, but .....

Post by grantspain » October 29th, 2008, 9:54 pm

best not to touch this and just get a replacement otherwise you may invalidate the warranty

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Re: I swapped my chassis for a tri-sync, but .....

Post by Jason » October 29th, 2008, 10:01 pm

grantspain wrote:best not to touch this and just get a replacement otherwise you may invalidate the warranty

umm... ok why is there pots on that chassis then?

These aren't made for direct fit into his tube, and you WILL have to do some sort of tunning to get them right...

Anyways he has alrighty messed with the pots so it really doesnt matter now.

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Re: I swapped my chassis for a tri-sync, but .....

Post by grantspain » October 29th, 2008, 10:19 pm

Jason wrote:
grantspain wrote:best not to touch this and just get a replacement otherwise you may invalidate the warranty

umm... ok why is there pots on that chassis then?

These aren't made for direct fit into his tube, and you WILL have to do some sort of tunning to get them right...

Anyways he has alrighty messed with the pots so it really doesnt matter now.
i meant soldering bits,smart **** ;)

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Re: I swapped my chassis for a tri-sync, but .....

Post by kernow » October 29th, 2008, 10:35 pm

Jason wrote:here you go buddy....
Image
I'd love an exact explanation of some of those chassis pots, in the manual not all are documented.
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Re: I swapped my chassis for a tri-sync, but .....

Post by poolchamp » October 29th, 2008, 11:46 pm

grantspain wrote:
Jason wrote:
grantspain wrote:best not to touch this and just get a replacement otherwise you may invalidate the warranty

umm... ok why is there pots on that chassis then?

These aren't made for direct fit into his tube, and you WILL have to do some sort of tunning to get them right...

Anyways he has alrighty messed with the pots so it really doesnt matter now.
i meant soldering bits,smart **** ;)
Well no need for me here then grant is correct on less your a gambler ;) Take the advice

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Re: I swapped my chassis for a tri-sync, but .....

Post by ckong » October 29th, 2008, 11:59 pm

grantspain wrote:best not to touch this and just get a replacement otherwise you may invalidate the warranty
Thank you all for the help and advice. I'll do what grantspain said, I did sent an e-mail to Fannie at Excellentcom and now I'll just wait and see what happens. For the time being I already swapped the chassis back (very good for acquiring chassis swapping skills, although the discharge part keeps giving me a bouncing heart), and to clear my head I'm now playing a bit of Salamander 2.

One last issue remains for tomorrow: because I had a tri-sync monitor connected to my Mame PC, I immediately installed the ultimarc Trysinc Utility ......... But now I have a two sync again. You guessed it, my windows screen is messed up as soon as the ArcadeVGA goes in 15Khz mode: I see two complete desktops on the screen, one left and one right. Oh well, I will need to reinstall the arcadeVGA drivers I guess.

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Re: I swapped my chassis for a tri-sync, but .....

Post by Jason » October 30th, 2008, 12:30 am

hehehe....

well messing with pots does get you somewhere, sorry about the confusion.

Image
Image

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