Original monitor woes

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Menace
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Re: Original monitor woes

Post by Menace » Tue Jun 01, 2010 4:22 pm

Hey guys, thought I'd chime in on this subject as I too had this issue with my original WG K7302 CRT and the ArcadeVGA. Here are the symptoms I ran into and the fix.

After installing my nucore PC with the AVGA I noticed right away that the pic was way too far to the left during boot as well as in game, and cranking the Horizontal Position pot on the remote control PCB didn't correct it. (image still too far to the left and missing partial image)

***NOTE*** Results may vary depending on the 'health' of your monitor. I take no responsibility for any results you may or may not obtain with the following.****

PLEASE PLEASE PLEASE make sure you are using insulated adjustment tools when performing any of these steps! (I recommend using a set of TV tuning tools - which is what I used) Also, as you probably already know space is very tight in the head of a P2K machine. Be careful when poking around any of the HV stuff.

The WG K7302 has a switch that will allow the user to select which type of sync it uses, either + or -. From all the reading I had done prior to buying my RFM, I knew that the original monitor was setup back-asswards in terms of sync compared to the "norm" for use with the OEM PC, so I ended up pressing the sync switch to change the sync polarity (with the power off) and this brought the pic back to a usable horizontal position. Readjusted the horizontal position with the remote control PCB and life was good. Now, if you find that you just can't seem to get the pic centered horizontally no matter which way you have the sync switch set, there is a trim pot on the main chassis called Horz Osc. (located at the top right of the pcb when looking at it from the front of your game) This pot will allow you to move the raster horizontal position, and then use the remote horizontal position pot to tweak. Set your horizontal position pot on the remote pcb in the middle, then adjust the Horiz Osc pot until the image is roughly centered, then use the remote to tweak it as needed. (the Horiz Osc is just a 'rough' setting)

As for adjusting the horizontal size of the pic, there is another trim pot on the main chassis next to the flyback (upper left of the PCB when looking at it from the front of your game) and if I recall correctly it's call Horiz Size. If your image is too large or small you'll need to adjust this pot to get it dialed in just right.

I think I spent a total of 5 mins start to finish tweaking my CRT and I couldn't be happier with the results. Everything lines up perfectly, better than it did from the factory!

Doug
Last edited by Menace on Tue Jun 01, 2010 4:29 pm, edited 2 times in total.

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JB
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Re: Original monitor woes

Post by JB » Tue Jun 01, 2010 4:28 pm

Doug,

Thanks for the info. My tests using the H-only sync did not go well; the WG monitor seems to need both H and V sync. I tried the polarity switch but it caused a scrambled image on the screen so I put it back the way it was. I will try it again tonight.

In other news, I have a possible replacement arriving tomorrow, a "Cherry Master" 19" CRT. I will post the results of that.

Thanks,
-JB

Menace
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Re: Original monitor woes

Post by Menace » Tue Jun 01, 2010 4:31 pm

JB wrote:Doug,

Thanks for the info. My tests using the H-only sync did not go well; the WG monitor seems to need both H and V sync. I tried the polarity switch but it caused a scrambled image on the screen so I put it back the way it was. I will try it again tonight.

In other news, I have a possible replacement arriving tomorrow, a "Cherry Master" 19" CRT. I will post the results of that.

Thanks,
-JB
If you got a scrambled pic you may just need to play with the horizontal position / horizontal osc controls to bring it back.

Doug

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Chuck
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Re: Original monitor woes

Post by Chuck » Tue Jun 01, 2010 4:44 pm

Thanks for the updates guys.

One thing to keep in mind if you are swapping the monitor don't get a replacement CGA monitor get a VGA and you won't need an arcadevga card.

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JB
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Re: Original monitor woes

Post by JB » Tue Jun 01, 2010 7:24 pm

Chuck,

I would LOVE to find a 19" VGA CRT that fits inside the P2K head and the old monitor frame! Got any leads? :wink:

Seriously, I should have seen this coming; I would have gone on this monitor hunt a year ago. Now there is nothing left!

-JB

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Chuck
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Re: Original monitor woes

Post by Chuck » Tue Jun 01, 2010 10:06 pm

JB wrote:Chuck,

I would LOVE to find a 19" VGA CRT that fits inside the P2K head and the old monitor frame! Got any leads? :wink:

Seriously, I should have seen this coming; I would have gone on this monitor hunt a year ago. Now there is nothing left!

-JB
I hate to admit this but i threw out a dozen 19" tubes a few years back :p I'll keep my eye open.

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JB
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Re: Original monitor woes

Post by JB » Wed Jun 02, 2010 2:30 am

SUCCESS!

The polarity switch Doug spoke of was the answer. A bit of adjustment on the horizontal osc and the horizontal size and the image is perfect.

Since I am also using the Ultimarc video amp (boosts the 1V video signal to 5V), the image was too hot, so I also adjusted the intensity down on the flyback transformer and the results are astounding. This monitor now has deep blacks and vibrant colors with no smearing, ghosting or burn-in. Perfect, clear picture.

Here is the signal flow:

Nucore computer -->
Ultimarc Arcade VGA card -->
Shielded VGA cable with ferrite rings at both ends -->
Ultimarc video amp -->
Original adjusted WG monitor (with a dab of rubber cement to keep the flyback setting locked in)

I declare: woo hoo.
-JB

Menace
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Re: Original monitor woes

Post by Menace » Wed Jun 02, 2010 10:11 am

Glad to hear you got it all dialed in!

Doug

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Chuck
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Re: Original monitor woes

Post by Chuck » Wed Jun 02, 2010 10:14 am

Nice job guys.

Menace
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Re: Original monitor woes

Post by Menace » Wed Jun 02, 2010 10:34 am

Maybe the instructions I posted should be added to an installation sticky somewhere when using an AVGA?

D

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Chuck
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Re: Original monitor woes

Post by Chuck » Wed Jun 02, 2010 10:39 am

Menace wrote:Maybe the instructions I posted should be added to an installation sticky somewhere when using an AVGA?

D
done

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