VGA + PVM-20L5 Issues

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strygo
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VGA + PVM-20L5 Issues

Post by strygo »

I checked in with the Lynx McWill thread on Atari Age but so far haven't had success there. I recently purchased the McWill Lynx mod and had it installed. The screen replacement is incredible and works great. However, I am running into an issue with the VGA output and I'm hoping someone might know the cause.

When I hook the Lynx up to a ViewSonic CRT monitor, the picture is fantastic. However, when I hook it up to my Sony PVM-20L5, the image is much darker with artifacts. I've tried two separate approaches for combining the sync. The first was to connect the Lynx up through an Extron 203rxi. The second approach was through a Behar Bros. Kenzei through a Sync Strike and finally the Extron 203. Both approaches produce the same distorted output.

You can see a comparison here: https://imgur.com/a/cEfM7sc

Does anyone have any ideas what might be causing this? Thank you for your help.
Last edited by strygo on Sun May 27, 2018 3:14 am, edited 1 time in total.
strygo
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Re: McWill Lynx VGA + PVM

Post by strygo »

So I scoured for others with similar problems and I found someone on Reddit that has been having what appears to be the same issue:

https://www.reddit.com/r/crtgaming/comm ... o_pvm20l5/

The person wasn't able to resolve his problem, but another commenter mentioned using an Extron Emotia. This reminded me of the 75 ohm attenuation switch on the rear of the Emotia. When testing my Emotia previously, this dramatically affected brightness. Does anyone know what this switch actually does and why it exists? The 'manual' for the Emotia is super sparse with no info. I'm hoping this may be a lead.
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nakedarthur
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Re: McWill Lynx VGA + PVM

Post by nakedarthur »

Sorry, I can't help, but happy to see another Lynx fan around here :) I also have the McWill mod, it's definitely awesome. Kinda regretting not getting a VGA port installed now.
strygo
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Re: VGA + PVM-20L5 Issues

Post by strygo »

I've updated the title of the thread. After doing some more testing with additional devices, including my DISPL, it would seem the discoloration I see when sending VGA to the 20L5 has to do with the 640x480 VGA signal and not specifically the McWill mod output.

I don't see this distortion when sending 480p sources like the GameCube, Xbox, etc. Is there something special about a VGA signal that would hurt compatibility with a PVM? I'll keep testing, but any leads are appreciated. :)
strygo
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Re: VGA + PVM-20L5 Issues

Post by strygo »

Alright, this is really weird. I briefly fixed my issue and I don't know why, but more importantly, the fix stopped working.

A commenter in the Reddit thread mentioning the OP should use an Extron rxi unit. I happen to have one right before my PVM, so I didn't pay much attention. I thought perhaps my 203 rxi unit was at fault so I figured I would try my other 201 rxi. Prior to disconnecting the 203 rxi unit, I figured I would toggle some of the dipswitches. I enabled ADSP (I normally leave it off and use DDSP) - boom - the picture looked just like the CRT monitor. I then adjusted the centering slightly and the picture went back to like before.

I then proceeded to test and retest toggling the dipswitch, powering off and on the device, and even trying the 201 rxi. Not since have I been able to fix the problem. :x I don't understand what could have happened when enabling ADSP the first time that would have corrected the problem.
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mikejmoffitt
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Re: VGA + PVM-20L5 Issues

Post by mikejmoffitt »

Go into the service menu and change Y-CLMP to a higher or lower number so it is no longer sampling clamping values during the active picture. No need for the extron device.
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Gara
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Re: VGA + PVM-20L5 Issues

Post by Gara »

I'm trying to run 480p from my Nvidia 980TI to the 20L5 and I am running into similar issues.
Dvi-I>VGA Adapter>VGA to VGA>Extron 203 rxi>RGBS
The VGA cable is 6ft. BNC RGBS output is 6ft. I am running Windows 10 and hooking it up as an extended desktop. I created the resolution using Nvidia control center custom resolution utility. 640 x 480, 60hz, progressive.

720p will display fine with normal brightness. When I switch to 480p the image goes very dark and there is a bright line across the top of the screen. The image looks like crap. Turning the level and peak knobs up most of the way helps. I tried the various switches on the Extron and none of them change the image. I have not tried messing with any of the internal switches. The extron reads the signal as "H 31.42k V 59.9Hz".

Anyone know what I am missing? This is all new territory for me so I am betting on a simple mistake somewhere. I'd like to be able to output 240p. If there is some trick to forcing that resolution on a 980TI I would appreciate the help.

Edit: http://imgur.com/gallery/wKbOB08
strygo
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Re: VGA + PVM-20L5 Issues

Post by strygo »

I haven't had a chance to try Mike's suggestion yet, although I couldn't find a reference to this setting in the 20L5 service manual. If I find a slightly differently named setting and it works, I'll update the thread.

I did some more hunting in the shmups archives and found a few threads from 2013 and 2014 with people facing similar problems when connecting a Dreamcast to the 20L5. Oddly, I don't have that problem via the Toro. In any case, there was consistent success with pairing the 20L5 with the Extron SS 200 Sync Stabilizer. If the service menu isn't the solution, one of these devices might address the problem.
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buttersoft
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Re: VGA + PVM-20L5 Issues

Post by buttersoft »

Not sure if this is related, or even helpful, but i thought i'd cross-reference:

http://forum.arcadecontrols.com/index.p ... 220.0.html
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mikejmoffitt
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Re: VGA + PVM-20L5 Issues

Post by mikejmoffitt »

strygo wrote:I haven't had a chance to try Mike's suggestion yet, although I couldn't find a reference to this setting in the 20L5 service manual. If I find a slightly differently named setting and it works, I'll update the thread.

I did some more hunting in the shmups archives and found a few threads from 2013 and 2014 with people facing similar problems when connecting a Dreamcast to the 20L5. Oddly, I don't have that problem via the Toro. In any case, there was consistent success with pairing the 20L5 with the Extron SS 200 Sync Stabilizer. If the service menu isn't the solution, one of these devices might address the problem.
This is your problem with an easy free fix! Try it instead of messing aobut with extron boxes!
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FriendofSonic
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Re: VGA + PVM-20L5 Issues

Post by FriendofSonic »

Mike, or anyone else here, I was going to do a PC build for emulation and what not on my 20L5. I had planned on using the Kenzei for combining sync-- is that all I need to do in order to use the PC on my 20L5? (as well as trying your suggestion, Mike should I encounter the same problems)
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Re: VGA + PVM-20L5 Issues

Post by strygo »

Mike, that worked! SWEET! 8)

For others, the setting I had to tweak was "CLP P DLY" and I increased the value from 200 to 217. This immediately corrected my coloration problem and it looks absolutely fantastic.
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Re: VGA + PVM-20L5 Issues

Post by strygo »

I did a bit more research in the service manual, and although this setting isn't explained, I did learn that it defaults to 225 for 15khz signals and 200 for 31khz. So for consistency sake, it might make sense to use 225.

In making the change, I have found no impact to other signals or a degradation in any way.
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mikejmoffitt
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Re: VGA + PVM-20L5 Issues

Post by mikejmoffitt »

Glad that worked.

I don't know of that box but it probably works fine to generate C-sync. I have used just an XNOR gate to generate it this way:

Code: Select all


/CSYNC := /VSYNC xnor /HSYNC

A 74LS266, a 0.1uF capacitor, and any 5V power source (USB is fine) will let you make a C-sync generator from TTL VGA sync signals.
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Overkill
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Re: VGA + PVM-20L5 Issues

Post by Overkill »

People I have the exact same issue on my Sony BVMD24E. Mine works great with my Dreamcast modded to vga, but on my Groovymame PC it gives me that strange colour on 640x480 31Khz. On 15khz games looks great. Now Reading all this Im trying to find that CLP P DLY option to adjust, but can't find it anywhere

Meanwhile…

Diging deep in the service menu I found it:

BK Board (6/7)

CLP P DLY - Value (This value changes when alternating between 15khz and 31khz

Before and after pics
https://ibb.co/eOJA5y
https://ibb.co/ix2EXd
strygo
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Re: VGA + PVM-20L5 Issues

Post by strygo »

Overkill wrote:People I have the exact same issue on my Sony BVMD24E. Mine works great with my Dreamcast modded to vga, but on my Groovymame PC it gives me that strange colour on 640x480 31Khz. On 15khz games looks great. Now Reading all this Im trying to find that CLP P DLY option to adjust, but can't find it anywhere

Meanwhile…

Diging deep in the service menu I found it:

BK Board (6/7)

CLP P DLY - Value (This value changes when alternating between 15khz and 31khz

Before and after pics
https://ibb.co/eOJA5y
https://ibb.co/ix2EXd
Keep changing the value until you observe a change in display. When I went to 217 and back to 216 for my PVM, the issue would fix itself and then come back. I assume with this BVM, the value you need to adjust to may be different, so you just need to find the right threshold to cross to resolve your problem.
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Overkill
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Re: VGA + PVM-20L5 Issues

Post by Overkill »

For 31Khz it was at 140, so I first increased it one by one and stoped at 146 where it correted the colors. Tried a 15khz and all fine so I thought it was all over. But then i tried to move picture horizontal a bit to the right and it gave me wrong colors again, so after the centering I go back to service menu and increased it to 150 and now seems fine, even moving picture again to far letf or right.

Don't know why but I can't use the new composite feature of Groovymame directly to this BVM, it won't sync. On my Philips cm8833 works great. Im using an arcadeforge UMSA to combine syncs
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Re: VGA + PVM-20L5 Issues

Post by strygo »

Given that the setting deals with tolerances of the sync pulse, it makes sense why adjusting the horizontal placement could require you to further tune this setting.

As for the other problem you describe, have you tried sending the signal through a Sync Strike?
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Overkill
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Re: VGA + PVM-20L5 Issues

Post by Overkill »

No, I don't have a Syncstrike anymore. But enabling composite sync on "video mode maker" don't should be clean sync already?

Using UMSA looks great with 15khz input but I still have a little distortion on the top of the image with 31khz input, with the extron 580 with the DDSP switch on resolves the issue
tisurame
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Re: VGA + PVM-20L5 Issues

Post by tisurame »

I also have some problem with my 20L5 when using 480p, but it looks different.

The picture looks distorted when using 480p, as you can see in the picture:

Image

720p and 1080i looks fine.

Same problem happens with Wii and Xbox 360 when using 480p.

CLP P DLY don't make any difference.

Any idea what is going on?
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Re: VGA + PVM-20L5 Issues

Post by strygo »

How are you connecting the consoles? Component or RGB? Any other devices in between?

I use a Garo + Kenzei to convert YPbPr component to RGB. This then goes through a SCART switch to the Sync Strike, which is responsible for cleaning the sync. An Extron 203rxi is the final stop before the PVM which converts RGBHV to RGBS. All of the consoles you mention work perfectly in 480p on my L5.

I suspect that you need something like a Sync Strike.
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Re: VGA + PVM-20L5 Issues

Post by tisurame »

strygo wrote:How are you connecting the consoles? Component or RGB? Any other devices in between?

I use a Garo + Kenzei to convert YPbPr component to RGB. This then goes through a SCART switch to the Sync Strike, which is responsible for cleaning the sync. An Extron 203rxi is the final stop before the PVM which converts RGBHV to RGBS. All of the consoles you mention work perfectly in 480p on my L5.

I suspect that you need something like a Sync Strike.
I'm using a custom YPbPr transcoder to connect the PC. About the consoles...I'm connecting it directly to the PVM using BNC to RCA adapters.

Are you using that device for cleaning the sync even when using the consoles (Wii or Xbox 360)?

When I first bought the PVM I remember testing the 20L5 for a brief moment with 480p using the Wii and it was working fine. After trying (unsuccessfully) to make it work with my PC (using a RGB-BNC to VGA cable) with 480p and others resolutions, the PVM started to give this problem even when using the Wii. Not sure if I damaged something when trying to make the PVM work with the PC (I don't know if it's even possible). In that case, I wonder what part of the PVM could be fixed...
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Re: VGA + PVM-20L5 Issues

Post by strygo »

I don’t have experience using YPbPr with the 20L5. Maybe others can weigh in. I wouldn’t expect component to have the sync related issues that RGB has (H+V vs. S, TTL vs 75ohm). I use RGB exclusively for consistency within my setup.
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Gara
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Re: VGA + PVM-20L5 Issues

Post by Gara »

mikejmoffitt wrote:Go into the service menu and change Y-CLMP to a higher or lower number so it is no longer sampling clamping values during the active picture. No need for the extron device.
Thank you! Also a big thanks to the OP for finding what the setting is called on the 20L5 and posting it. This was the issue on my 20L5 with 480p. My base setting was 200. It showed no change all the way until 223 then the screen went from dark and ugly to bright and beautiful in one notch. I left it at 225 and it doesn't seem to affect 240p at all.

Does anyone know if 24khz works on the 20L5? I searched through various comments from over the years most of them say no, I saw a few that said it works. I'm assuming those few are mistaken. My Crt Emudriver setup is currently treating 24khz titles as 31khz.
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mikejmoffitt
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Re: VGA + PVM-20L5 Issues

Post by mikejmoffitt »

Nope, no 24KHz for the L5 series.
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Gara
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Re: VGA + PVM-20L5 Issues

Post by Gara »

mikejmoffitt wrote:Nope, no 24KHz for the L5 series.
Thank you for letting me know. I was reluctant to try it after all the trouble of 15 khz and 31khz. Maybe one day I'll have an Astro City cab and I can do 24khz right.
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