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Thread: Nanao MS7-20L to Weiya 820HR Swap and a Question

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    Nanao MS7-20L to Weiya 820HR Swap and a Question

    After just recently finishing my first monitor restoration (a WG K7000 dead flyback and HOT), I also received my repaired Outrun PCB from the UK and could finally play that game. Sadly I realised I'd be doing my second monitor restore already as this one in the Outrun (a Nanao MS7-20L) would slowly go blurry after 15 minutes or so. After about 45 minutes the game wasn't playable at all.

    After a bit of research it looked like it was a clear sign of the flyback failing. This seemed about right as I could adjust the focus on the flyback and it would look pretty good for a minute or so but then start blurring again.

    More research into this monitor revealed there's no replacement flyback. So it was time to contact Jomac and see if there's anything that could be done. Joey got back to me straight away and confirmed my research - there's no replacement flyback but there's a replacement chassis that I think is a universal chassis? Anyway it's a Wei-Ya 820HR. I quickly ordered this and hoped to get it the next day - I had guests coming around for the weekend and I wanted Outrun up and running! Amazingly, Joey and crew did an awesome job and had it in my hands next day.

    I'm still a little green when it comes to this monitor malarkey. As mentioned I've only done one before. But jumping straight in and discharging the old beast and - I still live! I'm still concerned about discharging monitors but I'm getting more comfortable as I go along.

    DKTcGssUQAEt5X-.jpg

    The chassis is out and it looks pretty dirty.

    DKTcGu_VoAAJv_0.jpg

    Then I flip it over and see this...

    DKTgIglVAAAKTSD.jpg

    Ouch! I'm surprised the thing works at all, let alone just focus issues. But knowing what problems I'm having I'm guessing whatever dodgy job the person did on this to keep it working did actually work. It might look nasty but it kept the thing humming along.

    The new chassis looks much much cleaner:

    DKTcGsrV4AA1-b3.jpg

    Throwing the new chassis in was pretty easy. Spliced in the power (the Wei-Ya had a power plug on the end that had to be snipped off), and the header for the video cable was different so spliced into that as well from the game PCB.

    I got a little stumped at one point - the tube has two ground wires coming off the degauss coil (the ground wires not the degauss coil connector). One going to the neck board which is fine, but on the old chassis one would plug into the chassis. I looked around for ages on the new chassis but there was no ground pin to plug this into. I seemed to recall on the K7000 that it didn't have one either and maybe the Nanao was just a bit unique in that respect. I spent a fair bit of time researching to make sure though (not plugging in ground wires is bad news - I know that much!). I rewatched a couple of John's Arcade youtube videos and reaffirmed my thoughts. I also scoured the internet for information on the Wei-Ya but this chassis may as well not exist - there's nothing out there on it, no manual or anything. I was pretty much flying blind (not that it's hard or anything but I don't want to get anything wrong).

    So anyway, after looking into this as much as I could I determined the extra ground wire was not needed for the tube so left it off.

    Plugged everything else back in, fired the game up and - success! The game is super sharp and focused, doesn't drift over time and looks great. I had to adjust some sizing and so forth but otherwise it looks good.

    DKUuYfnUEAACt0X.jpg

    But it's not all roses I'm afraid. I now have another issue and I'm hoping @Jomac or someone else can give me some advice:

    The monitor colours go 'hot and cold' (is probably the best way to describe it). You can see in the above picture, that it's too yellow and red. Well it does that and then in other parts of the game the colours go back to normal. And in other parts, it goes colder and goes darker and more blue. It's like the chassis is interpreting what the game is outputting and putting too much colour into areas it shouldn't be. It's doing it in all the same parts of the game so it's not the monitor going in and out at random, it's being told to display these colours depending what the game is doing and making them too bright or too dull. It's a bit jarring too because when you go uphill it goes hot yellow / red, and when downhill it goes back to normal. In Outrun, that can be separated by seconds over and over so it's very obvious.

    It didn't do this on the old monitor (nor the monitor used on the bench for the repair for the guy in the UK) so I can rule out that it's the game PCB. Something weird is happening with the new chassis or the tube I reckon. I've tried playing with all of the pots, the flyback screen and focus, and degaussing with a degauss wand. Nothing I do changes the fact the colours go hot and cold.

    Any suggestions?

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    Can't resist having a stab before Joey gets here to see if I'm right

    Assuming the chassis is working properly, i reckon it's a case of the beam-current limit vs the video levels being too high. The chassis will only deliver so much drive and no more. If the levels were balanced on a static image, and the contrast was as high as it would go, and you then turned up the red colour, the red would get brighter while the green and blue dimmed slightly to compensate, and the overall image brightness wouldn't change. Though a redder image often looks slightly dimmer.

    If you drop the overall contrast, does the problem still occur?

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    Quote Originally Posted by buttersoft View Post
    Can't resist having a stab before Joey gets here to see if I'm right

    Assuming the chassis is working properly, i reckon it's a case of the beam-current limit vs the video levels being too high. The chassis will only deliver so much drive and no more. If the levels were balanced on a static image, and the contrast was as high as it would go, and you then turned up the red colour, the red would get brighter while the green and blue dimmed slightly to compensate, and the overall image brightness wouldn't change. Though a redder image often looks slightly dimmer.

    If you drop the overall contrast, does the problem still occur?
    Thanks for the suggestion, much appreciated. I didn't know that colours would dim to compensate for other colours so perhaps that's on the right track. I'll try fiddling with the contrast again when I'm next in the arcade.

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    Quote Originally Posted by Mar View Post
    I didn't know that colours would dim to compensate for other colours so perhaps that's on the right track.
    Some chassis, in particular for TV's, can have each channel sort of buffered, so each colour sets it's own level. From memory the Wei Ya's are kind of all-in prospect though, rather than separated.

    TBH this is just a guess, and i'd listen to what @Jomac says first, but it can't hurt to turn the screen settings down and see what happens.

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    Quote Originally Posted by buttersoft View Post
    Can't resist having a stab before Joey gets here to see if I'm right

    Assuming the chassis is working properly, i reckon it's a case of the beam-current limit vs the video levels being too high. The chassis will only deliver so much drive and no more. If the levels were balanced on a static image, and the contrast was as high as it would go, and you then turned up the red colour, the red would get brighter while the green and blue dimmed slightly to compensate, and the overall image brightness wouldn't change. Though a redder image often looks slightly dimmer.

    If you drop the overall contrast, does the problem still occur?
    Great post and pretty much on the money,
    There is only so much drive a chassis can deliver and to be fair we are comparing the Rolls Royce of 20" chassis in the Japanese Nanao MS7-20L to a KIA , The Nanao has a little module on the front that hasn't been replicated as well on any other chassis, It amplifies , mixes and compares the incoming signal then references it to the ABL , Automatic Black Level , in essence self adjusting the contrast levels on the fly.

    With the Weiya like 90% of 20" chassis will as buttersoft mentioned basically have the drive limit shared across the 3 colors that is set to deliver pure white ( a combination of all 3 together )driving a maximum at what is considered an acceptable level , the acceptable level is supposed to be cut off / reduced when reaching close to Xray protection level.
    You need to set each color so that on a purity test pattern you are getting perfect white.
    It's possible with pretty much any chassis to disregard Xray protection and bring levels way beyond a safe range , (enough to see your breakfast ! ) but not something I would ever supply.

    The original Mitsubishi tube you have was actually a bit inefficient compared to more modern tubes but as the Nanao was designed to perfectly drive them they had the best picture available, the Weiya chassis made much later didn't need this capability so are working quite hard on the older CRT's but more than acceptable especially considering nothing else is left in the market that will work on them tubes.

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    Quote Originally Posted by Jomac View Post
    Great post and pretty much on the money,
    There is only so much drive a chassis can deliver and to be fair we are comparing the Rolls Royce of 20" chassis in the Japanese Nanao MS7-20L to a KIA , The Nanao has a little module on the front that hasn't been replicated as well on any other chassis, It amplifies , mixes and compares the incoming signal then references it to the ABL , Automatic Black Level , in essence self adjusting the contrast levels on the fly.

    With the Weiya like 90% of 20" chassis will as buttersoft mentioned basically have the drive limit shared across the 3 colors that is set to deliver pure white ( a combination of all 3 together )driving a maximum at what is considered an acceptable level , the acceptable level is supposed to be cut off / reduced when reaching close to Xray protection level.
    You need to set each color so that on a purity test pattern you are getting perfect white.
    It's possible with pretty much any chassis to disregard Xray protection and bring levels way beyond a safe range , (enough to see your breakfast ! ) but not something I would ever supply.

    The original Mitsubishi tube you have was actually a bit inefficient compared to more modern tubes but as the Nanao was designed to perfectly drive them they had the best picture available, the Weiya chassis made much later didn't need this capability so are working quite hard on the older CRT's but more than acceptable especially considering nothing else is left in the market that will work on them tubes.
    Thanks Joey, it's great to hear this and confirm what the issue is. I'll play around with the settings next time I'm in the arcade (likely Friday night). It sounds like I should be able to get the colours to normalise some more which is good news as it's a little jarring at the moment, but I'm actually happy regardless as it at least means I did nothing wrong! The second stage (turning right) in the game is the worst as it goes a dark blue so I should be able to normalise that a bit more to neutral hopefully. It's also much better even as it is now than it was before because at least I can play the game perfectly - having the game in focus and the colours funny is better than not being able to see any of the oncoming cars!

    Thanks again.

    Marc.

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    Design us a chassis, Joey! You could do that and then sell them, and live like a king on the profits...

    Quote Originally Posted by Jomac View Post
    There is only so much drive a chassis can deliver and to be fair we are comparing the Rolls Royce of 20" chassis in the Japanese Nanao MS7-20L to a KIA , The Nanao has a little module on the front that hasn't been replicated as well on any other chassis, It amplifies , mixes and compares the incoming signal then references it to the ABL , Automatic Black Level , in essence self adjusting the contrast levels on the fly.

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    Finally got some time to play with the monitor again.

    First problem: There is no contrast control on the WeiYa chassis! So there goes that idea. However, I learned that the cutoffs are basically contrast anyway so I turned those down and then played with the other pots (gains and screen). The hot / cold colours are still doing what they were doing, but to a slightly lesser degree. I've come to accept that this is just what this chassis is going to look like and I'll live with it.

    Not entirely happy with the chassis but the game is completely playable so it was worth the money (and time) for sure. However, later on down the track I do plan to maybe change out the entire monitor or attempt to repair the Nanao. The changing colours are just annoying enough that I won't be happy until it looks right.

    Thanks all for the tips, and thanks again to @Jomac for the chassis, great service and advice.


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