Basic right shift for RGB+CRT?

[andykara2003]

I've wanted to find a decent RGB shifter for many years, but have never come acoss a decent on that works. I have the Aliexpress one that does vertical and horizontal shift which causes image instability, Arcadeforge's board that's terrible and an older one just called the deluxe RGB shifter that causes the top of the image to skew.

Since there's no working options for this & I don't want to go down the route of sync strike/Extron, I was wondering if there might be a possibility of a very simple circuit that just shifts the image right an inch or so - basically to where a composite image would display? I don't really need a variable adjustment as I can do that using the horizontal adjustment pot on my CRT. It's just that the pot doesn't quite make the full adjustment - i.e. there's still a small black bar even if adjusted fully to the right. So just an extra inch to the right would be perfect.

All in all, I'm wondering if a simple set circuit without adjustable controls might be more likely to do the job without all these image problems all these adjustable units have?

[fernan1234]

I know it's not the solution you're looking for, but in case it may be worth considering, you can try just underscanning the picture so it doesn't really matter much whether some stuff lands more to the right or left in the end.

[andykara2003]

I know it's not the solution you're looking for, but in case it may be worth considering, you can try just underscanning the picture so it doesn't really matter much whether some stuff lands more to the right or left in the end.

Thanks, no that was useful but I’m a stickler for having the whole screen filled.

[TheRetroCarrot]

Out of curiosity is rgb shift something someone would run into with a setup like an rgb modded snes with a retro vision component cable to consumer CRTs like a Trinitron? I'm just starting the process of modding some of my systems and was unaware of this prior.

[andykara2003]

Out of curiosity is rgb shift something someone would run into with a setup like an rgb modded snes with a retro vision component cable to consumer CRTs like a Trinitron? I'm just starting the process of modding some of my systems and was unaware of this prior.

I think so - as far as I know, all consoles with RGB have that problem. But it’s usually OK as there’s often enough control in the service menu to correct it. Mine’s an early 90s model, gough, before service menus came to the line so adjustments are done via potentiometers on the board. Mine just doesn’t have enough compensation to sort it.

Damnit, I've made a decision on the setup which means I'll need both manual and vertical adjustment. I'll make a thread about using the Extron, I think this is my only reliable option now. Apologies for wasting time..

[Unseen]

All in all, I'm wondering if a simple set circuit without adjustable controls might be more likely to do the job without all these image problems all these adjustable units have?

Unfortunately this problem isn't exactly simple - assuming that you don't tweak it on the display, the position of the image is defined by the timing of the sync pulses in the signal, so if you want to move the visible part of it, you need to change where that part occurs in the signal relative to the sync signals. For shifting the image to the right you could in theory store that part of the signal and play it back with a small delay while keeping the sync signals the same, but this requires either digitizing the image (not simple) or an analog delay line, but nowadays these things are rare and I'm not sure if there ever have been adjustable ones.

The other option would be to keep the image part of the signal where it is and change where the sync signals are - but then you need to shift the sync in the opposite direction, so it would now need to occur earlier than it does in the normal signal. Since this is opposite to the usual flow of time, a bit of trickery is needed - while this is simpler than a full image capture/delay, it again is not a simple circuit, especially if you want it to work not just with progressive but also interlaced signals.

[andykara2003]

All in all, I'm wondering if a simple set circuit without adjustable controls might be more likely to do the job without all these image problems all these adjustable units have?

Unfortunately this problem isn't exactly simple - assuming that you don't tweak it on the display, the position of the image is defined by the timing of the sync pulses in the signal, so if you want to move the visible part of it, you need to change where that part occurs in the signal relative to the sync signals. For shifting the image to the right you could in theory store that part of the signal and play it back with a small delay while keeping the sync signals the same, but this requires either digitizing the image (not simple) or an analog delay line, but nowadays these things are rare and I'm not sure if there ever have been adjustable ones.

The other option would be to keep the image part of the signal where it is and change where the sync signals are - but then you need to shift the sync in the opposite direction, so it would now need to occur earlier than it does in the normal signal. Since this is opposite to the usual flow of time, a bit of trickery is needed - while this is simpler than a full image capture/delay, it again is not a simple circuit, especially if you want it to work not just with progressive but also interlaced signals.

Thanks for your reply, very much appreciated from such an expert.

Perhaps the Extron RGB201/3 route is the only reliable option then. I just have a feeling it can’t do 240p in & 240p out while also retaining the left/right/up/down image controls..

[kitty666cats]

OP, are you using sync on composite video cables by any chance? If so I’d try sync on luma cables instead

[andykara2003]

OP, are you using sync on composite video cables by any chance? If so I’d try sync on luma cables instead

Would that remove the left shift? That’d be a fantastic simple solution!

[kitty666cats]

OP, are you using sync on composite video cables by any chance? If so I’d try sync on luma cables instead

Would that remove the left shift? That’d be a fantastic simple solution!

It’s quite likely it would

[andykara2003]

It’s quite likely it would

Really appreciate it, thanks :) I had a modder fit Tim’s (eTim) RGB mod with deblur. Is it likely that the sync from Luna has been cut/deactivated? And is there any way I can tell?

If not, I’ll buy one of Retro Access’ excellent (and expensive!) sync on luma cables..

[Taiyaki]

I think N64 is always a bit to the right (or left, can't remember) even with the old RGBAMP, so it's not likely to make a difference. I'm using a retro access cables with csync and it's like that too (the csync cables should theoretically be best suited for the N64RGB).

It's the only console in my setup of 10+ Scarts to be off by a bit. All the rest are more or less around the same centering, and the Component consoles I've tweaked thanks to built in settings (Gamecube, Wii, and Groovymame).

The short of it is I don't think you can get that fixed short of using an Extron or a BVM and setting the N64 to a different channel with a different centering. If you're like me and favor consumer CRT's then I'd just say try to not let it bother you. Isn't it only off by a few lines anyway?

[andykara2003]

I think N64 is always a bit to the right (or left, can't remember) even with the old RGBAMP, so it's not likely to make a difference. I'm using a retro access cables with csync and it's like that too (the csync cables should theoretically be best suited for the N64RGB).

It's the only console in my setup of 10+ Scarts to be off by a bit. All the rest are more or less around the same centering, and the Component consoles I've tweaked thanks to built in settings (Gamecube, Wii, and Groovymame).

The short of it is I don't think you can get that fixed short of using an Extron or a BVM and setting the N64 to a different channel with a different centering. If you're like me and favor consumer CRT's then I'd just say try to not let it bother you. Isn't it only off by a few lines anyway?

Interesting, I thought it was just the basic nature of RGB to be to the left a bit. Either way, it's the nature of the sync that pushes it to the left - I'm wondering how luma would affect it, I'll ask Fudoh, he might know..

[orange808]

It's not really the nature of any color space, is it? Extron got started because of this phenomenon in 1983. The sync processor box was their first product.

Extron made their sync processing boxes for professionals that needed to feed multiple sources into a monitor, but it's understood that each source had a different signal output and nobody was adhering to any real standards. Centering and different sync standards were a problem if you wanted to use one screen.

Their first sync processor even predated real multisync displays. Later, NEC came in with the multisync monitors and things really took off. Good multisync monitors were a natural partner for the Extron sync boxes and the adapter cables Extron sold. The Extron could standardize the sync and clean up a lot of idiosyncracies of each source machine (including centering the image).

It makes sense that we would buy an Extron for this use case. Extron came into the world selling machines to professionals to solve this issue when CRT monitors were the standard. Why would I go to AliExpress and try to buy some cheap thing that someone made as a hobby thing in China?

[Taiyaki]

I think N64 is always a bit to the right (or left, can't remember) even with the old RGBAMP, so it's not likely to make a difference. I'm using a retro access cables with csync and it's like that too (the csync cables should theoretically be best suited for the N64RGB).

It's the only console in my setup of 10+ Scarts to be off by a bit. All the rest are more or less around the same centering, and the Component consoles I've tweaked thanks to built in settings (Gamecube, Wii, and Groovymame).

The short of it is I don't think you can get that fixed short of using an Extron or a BVM and setting the N64 to a different channel with a different centering. If you're like me and favor consumer CRT's then I'd just say try to not let it bother you. Isn't it only off by a few lines anyway?

Interesting, I thought it was just the basic nature of RGB to be to the left a bit. Either way, it's the nature of the sync that pushes it to the left - I'm wondering how luma would affect it, I'll ask Fudoh, he might know..

Yes it is the basic nature and RGB with sync on Luma does the same on my PS1 and PS2. I center my TV's horizontal position based on the RGB scart connections, and thus I needed to center the component connected connections too but fortunately those all had settings allowing for this to be done. The N64 was the only console where if you look closely ends up being somewhat off center, but again not by much imo.

[andykara2003]

Fudoh has very kindly said that he'll email a friend who used to make RGB shifters to ask about sync on luma. What a decent bloke.

[andykara2003]

Yes it is the basic nature and RGB with sync on Luma does the same on my PS1 and PS2. I center my TV's horizontal position based on the RGB scart connections, and thus I needed to center the component connected connections too but fortunately those all had settings allowing for this to be done. The N64 was the only console where if you look closely ends up being somewhat off center, but again not by much imo.

Thanks for that, looks like sync on luma might not make a difference then..

[matt]

First, what TV are you using? That makes a difference.

Second, what's wrong with an Extron unit? They're really cheap and work great. I use an Extron RGB 192 for this (when needed) and have no complaints. I think it cost $20.

Using luma from your console as a sync source won't make a difference vs composite video or composite sync. However, using the Luma input on your TV (if it has one) as a sync input will cause less of a horizontal shift than using a composite video input.

[andykara2003]

what's wrong with an Extron unit? They're really cheap and work great. I use an Extron RGB 192 for this (when needed) and have no complaints. I think it cost $20.

Thanks for this - I have a Sony Trinitron consumer TV from 1992 (bought it brand new a couple of years ago).

The main question is are you feeding 240p in and getting 240p out? I wasn't sure if that was possible with the Extrons so it'd be great if you are managing that.

So following your suggestion, I'll lay out the signal chain I think I'll need & I'll appreciate any corrections I already own an Extron RGB203Rxi which has horizontal and vertical shift so I'll use that:

1: Scart plug from console plugs into an arcadeforge sync strike as the Extron needs stripped sync.
2: D-sub15 from sync strike to Extron
3: Need to work out settings on Extron
4: Output of Extron is TTL sync so Dsub15 cable to etim's VGA to scart converter to down covert sync to composite sync that a consumer TV can handle ( the unit is a scart plug, so stright into TV.

Does that sound OK? The only doubt is that someone on the forums has questioned whether the shift controls will work in this instance:

"This was my experience with the Extron's, I had flagging and turning off(on?) ADSP fixed that but you lost the centering controls."

I'd hate to go to all that bother & find the controls need to be bypassed!

[orange808]

The Extron RGB units can handle CGA and that's 200p. If there is a minimum required amount of lines for the input signal, it's suitably low. I haven't had any issues related to any specific amount of lines in the signal.

[andykara2003]

The Extron RGB units can handle CGA and that's 200p. If there is a minimum required amount of lines for the input signal, it's suitably low. I haven't had any issues related to any specific amount of lines in the signal.

Good to know, thanks. So its just the matter if the Extron will process the 240p signal and also output 240p without 'flagging' while the H/V controls are active - which that guy mentioned and that I've also come across with RGB shifters before. If it does produce flagging, then the only way to sort it is by disabling the horizontal and vertical controls.

Looks like the only way to check is by trying it. Thanks all, I'll leave it there. I have some of the kit needed so that's a start if/when needed. I really appreciate all the help :)

[matt]

Thanks for this - I have a Sony Trinitron consumer TV from 1992 (bought it brand new a couple of years ago).

The main question is are you feeding 240p in and getting 240p out? I wasn't sure if that was possible with the Extrons so it'd be great if you are managing that.

So following your suggestion, I'll lay out the signal chain I think I'll need & I'll appreciate any corrections I already own an Extron RGB203Rxi which has horizontal and vertical shift so I'll use that:

1: Scart plug from console plugs into an arcadeforge sync strike as the Extron needs stripped sync.
2: D-sub15 from sync strike to Extron
3: Need to work out settings on Extron
4: Output of Extron is TTL sync so Dsub15 cable to etim's VGA to scart converter to down covert sync to composite sync that a consumer TV can handle ( the unit is a scart plug, so stright into TV.

Does that sound OK? The only doubt is that someone on the forums has questioned whether the shift controls will work in this instance:

"This was my experience with the Extron's, I had flagging and turning off(on?) ADSP fixed that but you lost the centering controls."

I'd hate to go to all that bother & find the controls need to be bypassed!

Thanks for clarifying - that makes a lot more sense.

The main problem with the Extron RGB units is indeed the sync issue. They work very well if you have a device that outputs composite or H/V sync, but RGB + composite won't work. Moreover, they don't fare well with the LM1881, and if you use a sync stripper that uses that chip you may not be able to use the horizontal shift properly. I haven't tried this with a 203Rxi but my 192 definitely chokes on it.

However, you may be able to get around that limitation by routing the RGB signals separately, and running sync by itself through the green input. The RGB unit should effectively function as a sync stripper while maintaining the horizontal shift function. You could either get composite sync, or even horizontally shifted composite video if you use the green output and enable SOG. With the latter option you wouldn't have to attenuate the sync output.

All that would be much easier to realize if you're able to make your own cables. Failing that, it should be possible to find the relevant adapters to make it work - you'd need a SCART to BNC adapter, female BNC to VGA, BNC to SCART, and 3 female to female BNC couplers.

[Melbont]

Been looking at the those Extrons too but didn’t want the hassle of a sync strike on the input plus my soldering skill isn’t great. I watched a review on those Aliexpress scart shifters and it looks like exactly what I need for my custom arcade cab

https://youtu.be/lxH2itK2w_k

[Moosmann]

an older one just called the deluxe RGB shifter that causes the top of the image to skew.

For this problem, I made the A-B switch:
https://playoffline.wordpress.com/cable/rgbshifter/

the Aliexpress one that does vertical and horizontal shift which causes image instability

That's one reason, why I didn't build vertical shifters back then. Instabilities can result from shifters that are not good adjustment (some TV`s need an other "basic" adjustment) or from an unshielded housing. However, there are also problems with the LM11881, since there seem to be many counterfeits.

[Gunstar]

an older one just called the deluxe RGB shifter that causes the top of the image to skew.

For this problem, I made the A-B switch:
https://playoffline.wordpress.com/cable/rgbshifter/

the Aliexpress one that does vertical and horizontal shift which causes image instability

That's one reason, why I didn't build vertical shifters back then. Instabilities can result from shifters that are not good adjustment (some TV`s need an other "basic" adjustment) or from an unshielded housing. However, there are also problems with the LM11881, since there seem to be many counterfeits.

Is this an improved recreation of the old deluxe RGB shifter? interesting, I wonder if the Aliexpress shifter is using a counterfeit LM1881 or perhaps it needs that capacitor you mentioned

In order to avoid instability, you can connect a 100nF Ker. switch capacitor.