Good Day everyone,

Following on the thread started on the Classified section, I am starting this new thread to talk about using a SVGA/VGA monitor to be used as a vector monitor for Tempest or StarWars to just a few...

Let's step back...
I guess everybody heard/read about what JROK did a couple year ago about modifying a regular CGA monitor to be converted in a vector monitor by just rewinding the yoke. Part of his conclusion was to relate the fact that the monitor was somehow missing some resolution and that he would try in the future a hi-res monitor to redo the test. Unfortunatly, it never happened and through out my struggle to rejuvinate my Tempest/SW monitors I took upon myself to go on from the point he left off...

So, I have acquired a MTG-1902EN (Vision Pro) from HAPP at 195.00 actually in sales!

I started playing around with it today and here are the different tests I have done so far...

My first goal was to be able to use that monitor has a vector monitor without modifying it the least, so my first thought was about trying to salvage the Yoke and use it as is without removing it.

So, I studied it for a while and I have realized that on each side of the vertical drive section, there is 4 layers of winding one on top of the other and that there is always a wire coming back to the origin. So for me, the I thought that I could use an intermediate tap for me to get a good impedance so I would have a descent scanning of the Y Axis. So, I manage to get in parallel 2 layers of winding on each side to get about the same impedance ( around 1.5Ohms) as the 6100.

Also, the VGA/SVGA are more fancy monitor when it comes to neck board, so instead of having a couple of transistor here there to drive the tube, I have this chip that is driving certain transistor then drive the tube. It also has this OSD feature that is bugging more then anything else...

Anyway, I have attached everything that needed to be attached and I fired it up... The firsts results where quite interresting but not fascinating. In terms of driving the yoke I think it was doing ok... the whole problem was with the colors and in the continuity of the lines being draw...

Actually I was seeing the redraw lines and all...

So, i did many tests... like changing the number of rows of winding, driving 1, 2 and 4. Driving 1, was not enough to get convergence, so we would see a horizontal line (because the monitor was not mounted in vertical position), 2 winding was pretty much the best I got, 4 would get the guns to shoot over the tube limits. However, All those test were always giving the same results in terms of not having a clear image because we would see the in between traces (redraw) like the guns don't shut off at some point or at the right time.

I also took my yoke off my 6100 tube I have putted on the VGA Tube and suprisingly enough the convergence was not bad at all, but still this retrace thing... So I sat down for a while thinking about it and I came up with possible answer:

1- My input inpedance at the neck board are not right and it is not enough for the level to not be optimised and the guns won't shut off at the time it is supposed to be. At this point I know they are not right, but would it be enough to cause that problem...
2- The second possible answer and which I think is really the big problem is that I am trying to feed a CGA timming type signal to a VGA/SVGA tube that is supposed to be driven twice as fast. So, I kinda realized that the persistance of the tube might be lower (less persistant then CGA tube) since it is refreshed more often. Which would mean that I will never see a full drawn vector image on it because of this fact!.

Which means that this project will end as quickly as it started and the conclusion would be: "You can't use VGA/SVGA monitor to be converted to be a 1980's vector monitor because of the reduced persistence" However, the goal was to get a higher resolution monitor to do the job. For me it easiest way was to use a VGA type. But I guess the real solution lies into finding a Higher resolution but still a 15K refresh as opposed as 31K.

At this point, I will try new test but on CGA type to see if there is a way to get something descent out of a regular type.
If you have any comment about it, just don't hesitate to let me know.

Ciao

Trinity

Good Day Everyone

Here is some news about my tests...

Despite the fact that yesterday's results were not very encouraging, I manage to fix the main problem I was having yesterday on the VGA monitor. Which was the first possible problem I have suggested, the RGB's signal are conditioned to drive the RGB guns directly as opposed as going trought the signal amplifier and all... So, I have bypassed the RGB amp and I drove the guns directly from the Tempest PCB. At that point I realized that was my major problem. However, I realized also that the orignal Vertical part of the yoke of that  monitor even if the resistance seem right, the impedance was too big thus too slow, so, when we are using it, we can see a distorsion in the image on the upper and downer of the image. So I replaced the original yoke with the 6100 yoke, I came about to have a perfect image. HOWEVER, my second possible problems yesterday remained right, even if the image is crispy clear and really nice, the persistance of it is still not enough, so the more info in the image, the more flashy it will be.

So, the real conclusion to this story is... can we use a VGA/SVGA monitor to create a Vector monitor out of it, YES and only YES if you manage to have the persistance of a CGA screen. So, in other word, if you can find a monitor that support CGA and VGA and has a very good dot pitch I guess it would be the perfect specimen. Otherwise, You will have to stick with the CGA for now.

Hope it helped.

Trinity

Well,

It seems that the plot thickens....

I might not have been right about my second assumption, that the persistance of the tube was causing this flashy refresh thing...

You see since the beginning, I have been doing tests on a VGA and on a CGA... Yesterday night I noticed that both had exactly the same CRT (same model) which meant many things!

First, that my persue to make the VGA model was pointless because the CGA version would give me the same type of resolution
Second, I realized that my problem was probably caused by a FLYBack running at 31Khz for the VGA as opposed to 15K for the CGA.

Right now, I made the CGA worked, but the image is not stable (jiggy & noisy), it seems that the Flyback might be causing the problem too.
I made the VGA worked too, but in that case, the lines are stable but they are flashy. Like there is a black redraw on top of them.

So, At this point, I will continue my investigation, so all is not lost ! but like I said, the conversion of the CGA is pretty straight forward and I guess there is no point into trying to get a VGA since both tube are the same (In that case 2 Vision Pro of course)

To be continued...

Trinity

PS: If peeps are interrested (which you don't seem to be) I could post in detail how to tranform a CGA monitor into a Vector Monitor.

Quoted from Trinity

PS: If peeps are interrested (which you don't seem to be) I could post in detail how to tranform a CGA monitor into a Vector Monitor.

It's not that we're not interested, but more likely that most (if not all ) of us
are several time-zones below your monitor technical level.

To many of us, ...well me anyways, you're almost talking another language !  

Beyond cap kits and fuses/transistor replacements, few of us would dare to mess with a monitor like that.


But hats off to you,  I'm sure your research holds great promise for all vector collectors...

Cheers,
Steph

I didn't see you had moved it here... what are you saying? That the vision-pro vga has the same tube as the cga model? Dot pitch is the same?

Could what you are seeing be the mask?

Quoted from tester007

I didn't see you had moved it here... what are you saying? That the vision-pro vga has the same tube as the cga model? Dot pitch is the same?

YES, the 2 Vision Pro model that I have purchased from HAPP which the OEM are
CGA -> Wells Gardner 7300
VGA -> Tovis MTG-1902EN

They both use exactly the same CRT tube a LG A48AQD220X if I recall. which is a .82 pitch type CRT

Mind you, I did not buy the most expensive Monitor around...

So, like I was mentionning, I pretty much figure out the NeckBoard setup, I pretty much figured out how to properly wind the yoke. BTW, the Horizontal yoke on the CGA one is arranged in series, so they have to be putted in parallel, otherwise the horizontal drive gets the image outside the tube.

However, on the CGA, the dispay is noisy like the WG6100 when the capacitor on the HV section ought to be changed. So, it is most probably something related to the High Voltage section.
on the VGA, the Flyback is driven from a 31K source and I suspect that the flyback system might create somekind of beating frequncy which would create this flashing effects.
In both cases, I think (and it is still is suggestion), the problem would be related to flyback system. Don't forget that both monitor don't drive any yoke windings anymore and none of them are fed with external signal, so the flyback transformer is being driven with a local free running Horizontal frequency. Also, the VGA version has a OSD system which complicate the extern system setup since everyting is being controlled digitally and obviously we can't use the OSD system anymore

I have to investigate more on that (the flyback system) or find a way to disable it. The best would be to have a simple oscillator system to drive the flyback transformer.

Trinity

PS: Make note that Flyback transformer is the part where the HV is created. the Flyback system is somekind of feedback loop that controls the transformer from the horizontal drive. see this actual link for more detail hxxp://an.hitchcock.org/repairfaq/sam/deflfaq.htm#dshdh

Quoted from tester007

Could what you are seeing be the mask?

What mask ?

Trin

Quoted from Steph

It's not that we're not interested, but more likely that most (if not all ) of us
are several time-zones below your monitor technical level.

ditto

The shadow mask..you said it looked like black lines. You can see them on a regular 6100 if you rotate the yoke.

Why would the stock flyback have any feedback? Could it be a frequency issue?

Quoted from tester007

The shadow mask..you said it looked like black lines. You can see them on a regular 6100 if you rotate the yoke.

Why would the stock flyback have any feedback? Could it be a frequency issue?

The phenomena on the VGA, because I don't have it on the CGA it is like I see somekind of retrace being done, it is like all the lines are there but each line are disapearing one after the other very quickly and then they reappear. This is done very quickly which give's a flashing motion on the lines, the only time we don't have this effect is when tempest is written on the screen you ear the yoke scanning very fast.

On a regular raster monitor you have the horizontal driver, driving one windings in the Flyback transo and the Horizontal windings of the Yoke. On one of the primary windings of the Flyback transformer, this signal is fed back to the Horizontal Oscillator (AFC, automatic frequency control). That pulse makes a close loop feedback system. In our case, we don't need that, but one of our problem is that we don't drive any yoke anymore, which suspect is unbalancing this feedback circuitry which in return get the HV voltage to oscillate... That's my theory, I will cut off the loop tonight and we will see.

tts,

trinity

PS: I  should have invested a little more and get a K7000 which has a .71 dot pitch instead... I guess it is going be the next one on my list !

Quoted from Trinity

Well,

PS: If peeps are interrested (which you don't seem to be) I could post in detail how to tranform a CGA monitor into a Vector Monitor.

Please keep posting on this.  I am loving this level of detail for a project that I may just take on someday.

newf

So how exactly are you driving this? You have the HV stock section driving the monitor, but have a 6100 deflection driving the stock neckboard and stock yoke or did you put the 6100 yoke on and use stock neckboard?

Have you tried unwinding the 6100 yoke and winding onto the stock yoke?

Quoted from tester007

So how exactly are you driving this? You have the HV stock section driving the monitor, but have a 6100 deflection driving the stock neckboard and stock yoke or did you put the 6100 yoke on and use stock neckboard?

Have you tried unwinding the 6100 yoke and winding onto the stock yoke?

Test,

The way it is setup now is that I wanted to used the maximum of the original monitor, because ultimatly I would just like to modify the original monitor and add a new deflection board. But right now, i use the CGA/VGA neck board, CGA/VGA original motherboard if you will (i.e, Flyback and all). I also use the original Yoke that I have rewinded the vertical part. So, the only thing I am using from my 6100 is the deflection board... period.

Basically, the 6100 deflection board drive both windings on the YOKE, the Game Board RGB output drive the Neckboard directly (like on the 6100) and the HV is created with CGA/VGA controller board since those monitor require 25K instead of 19K.

I did not have enough time yesterday to try my Flyback feedback system theory. I should have enough time to do it tonight, I will keep you updated about it...

At this point I will try to make my CGA work first.

Trinity

Just to keep you updated on my effort to transform a Raster into a Vector.

So far, I have yet elucidated the problem on Both monitor that I have to achieve a perfect image, no jiggy or noisy or whatever.

Let's step back here...
There is 3 components that needs to be address in order to drive the CRT:
1- The neck board - RGB component <--- I am quite sure at this point that both monitor are being driven the right way but neck board are different from one board to the other.

2- The Yoke deflection board <--- Despite the fact that my Yoke is not totaly perfect, I have 50% of chance to be ok, however I found out yesterday that a not well winded yoke can create lot of ringing (which could possibly expain the behavior on the CGA)

3- The HV section, in the CGA case, the Flyback is being driven at 15Khz and in the VGA case it is beinh Driven at 31Khz. In the 6100 the flyback is driven at 20KHz. Our problem in that case might be the beating Frequency that might be introduced. However, modifying those would be increasing the HV Voltage at the tube and I just don't know if the HOT (Horizontal Output Transistor) would support it, thus blowing up the whole thing.

Also, important fact to note is that We are driving a CGA and VGA monitor that has the exact same tube. In my test those tube are driven by the same YOKE and the same deflection board. What differs is the Neck Board and the HV section.

Finally, I am wondering why JROK did not get those problems, he just rewinded the yoke and that's it, no noisy images or flashy images, however he was using a Ampliphone deflection board... I use a WG6100 deflection board....

Hum... so many questions....

Trinity

Quoted from Trinity

Finally, I am wondering why JROK did not get those problems, he just rewinded the yoke and that's it, no noisy images or flashy images, however he was using a Ampliphone deflection board... I use a WG6100 deflection board....

Trinity

Well you don't know how many problems he had prior to getting it going... he could have had major issues then put that page together when he solved it quick and dirty like. I emailed him and asked him to take a look at this thread a few days ago but never heard back.

Quoted from tester007

Well you don't know how many problems he had prior to getting it going... he could have had major issues then put that page together when he solved it quick and dirty like. I emailed him and asked him to take a look at this thread a few days ago but never heard back.

Tester,

Thanks for the help!

I am presently looking into the winding of Yoke. It seems that the vertical yoke is ringing by nature, because of the interaction between the Vertical Winding and the Horizontal one. The phenomena created by the ringing on the Yoke could certainly explain the noisy lines on the CGA monitor. So I am presently looking different method to solve the problem... some are directly related to the windings itself and others are electronic in nature (RC filter). I guess these days ringing is usually handled electronicaly with filters on the board. This is might be the solution to the problem... will see, I don't give up on it, however I beleive that the CGA might b e easier to fix so I am concentrating on it now...

I will keep you updated !

Trinity

PS: Then again, I am wondering why I have some noisy lines on the CGA and not the VGA... this is very strange... Same tube, same yoke, same deflection board but one has noise and not the other.... Hum...

Good Day Gentlemen, (and Ladies if there more then 1 )

Well a little bit of an update on my quest to get a CGA/VGA monitor work as a Vector Monitor.

CHIZAM!, I finally found the problem on the VGA one. The problem was that the retrace was somehow slowdown or we had somekind of a black retrace... Since bothe Model use the same tube, I was about to switch neck boards and I realized that even if the tube was the same it was driven differently... and the main difference was the "GRID1" drive, it is not been driven on the CGA so, I have unconnected the G1 Drive on the VGA and that solved the problem...

So at this point, I have a VGA monitor working without this retrace thing anymore. It is a little bit noisy but I think most of my noise is comming from the ringing of my bottom Yoke part which is not exactly the same as top one. So, I guess I will optimze my YOKE windings, which I found a way to wind and limit the ringing on it.

More to come...

Trinity

Sounds good!

Quoted from tester007

Sounds good!

Some Images

Colors sucks! So don't worry, I have a nice bright RED, GREEN and BLUE!

Trinity

PS: FYI, This the VGA Vision Pro, MTG-1902EN with a .82 Dot Pitch, certainly not the best VGA dot pitch ever !

Excellent! so what is your next step?
I have a couple 6100 yokes and a Tovis svga monitor so would like to try this out...maybe I should find a higher dot pitch one though...

Quoted from tester007

Excellent! so what is your next step?
I have a couple 6100 yokes and a Tovis svga monitor so would like to try this out...maybe I should find a higher dot pitch one though...

Well, Yesterday night I have rewinded (again...) my 2 vertical yoke and I made sure they both would be the same. I guess I am becoming good at it now... So far I have improved on it... however it is not perfect and I don't think anybody that will try this will get it to be perfect and peeps have to keep that in mind. This VGA modification things is for me an excellent solution to replace any WellsGardner or Amplifone monitor. Again like I said, it is not perfect. In my actual case, the overall convergence is pretty good, however, when the lines are going off limit at the top and bottom, it seems that there is one of the yoke that get saturated and you see the line bend... At this point you only see it, when you are zaping withing one maze and then to reappear in the next one. For me this is acceptable, I will try to find the problem one way or the other but it could happen to anybody (I did not have this problem on the CGA by the way, same yoke).

Anyway, my point was just to let peeps know that, it is a great solution but it is not perfect, but I guess the WG and Amplifone are not perfect anymore either.

Ok, now, Happ sells a WG7000 (that got replaced with another model ie 7700 I think) anyway, WG claim to have a .71 dot pitch, this is not half bad and the monitor is a CGA. BTW, Something that might cause my noise problem on the CGA is the switching power supply which act as a isolation barrier. Anyway, that WG7700 doesn't have this Switching PS at the input, so I guess this WG7700 could be a very good choice.

If you are trying to find another VGA with a better dot pitch you might find yourself in a difficult possition since, the more precise and the more resolution the monitor has the more complicated and integrated the monitor circuitry is, so it makes it more difficult to hack into it. The CGA monitors is the simpliest circuitry you can find and these are the easiest to modify as well.

So, since you have some Tovis, are they the same as the one I have done ? You could probably hack in one of the them and I could help you out. I think the best thing is still to use the original YOKE and rewind it, you should sell those WG6100 instead ! But to understand and practice those could be usefull.

So, let me know what YOU want to do ! In my case, I will probably get myself a brand new WG6100 Driver Board and I will have a brand new monitor setup.

Trinity

Quoted from Trinity

Well, Yesterday night I have rewinded (again...) my 2 vertical yoke and I made sure they both would be the same. I guess I am becoming good at it now... So far I have improved on it... however it is not perfect and I don't think anybody that will try this will get it to be perfect and peeps have to keep that in mind. This VGA modification things is for me an excellent solution to replace any WellsGardner or Amplifone monitor. Again like I said, it is not perfect. In my actual case, the overall convergence is pretty good, however, when the lines are going off limit at the top and bottom, it seems that there is one of the yoke that get saturated and you see the line bend... At this point you only see it, when you are zaping withing one maze and then to reappear in the next one. For me this is acceptable, I will try to find the problem one way or the other but it could happen to anybody (I did not have this problem on the CGA by the way, same yoke).

What did you do to wind? Did you add or subtract windings as you tested? Jrok had a certain number of windings..did you match that?

Quoted Text

Anyway, my point was just to let peeps know that, it is a great solution but it is not perfect, but I guess the WG and Amplifone are not perfect anymore either.

Ok, now, Happ sells a WG7000 (that got replaced with another model ie 7700 I think) anyway, WG claim to have a .71 dot pitch, this is not half bad and the monitor is a CGA. BTW, Something that might cause my noise problem on the CGA is the switching power supply which act as a isolation barrier. Anyway, that WG7700 doesn't have this Switching PS at the input, so I guess this WG7700 could be a very good choice.

If you are trying to find another VGA with a better dot pitch you might find yourself in a difficult possition since, the more precise and the more resolution the monitor has the more complicated and integrated the monitor circuitry is, so it makes it more difficult to hack into it. The CGA monitors is the simpliest circuitry you can find and these are the easiest to modify as well.

So, since you have some Tovis, are they the same as the one I have done ?

Hmmm.. I am looking on the website and it says .26 dotpitch. Man...and I just sold off a bunch of these because I thought I couldn't use them...ARggghh!

Quoted Text

So, let me know what YOU want to do ! In my case, I will probably get myself a brand new WG6100 Driver Board and I will have a brand new monitor setup.

Trinity

Don't buy the repro deflection..it sucks.. I just sold off the two I had and went back to original. replace resistors and caps and you should have no worries.
I think I will start on theis Tovis then! I will probably use a 6100 yoke to re-wind on the Tovis yoke just to get it exact..I'll need your help on disbling G1 if I need to.

Quoted from tester007

What did you do to wind? Did you add or subtract windings as you tested? Jrok had a certain number of windings..did you match that?

I used my hands and finguer to wind! , I wond 46 turns on one side and 46 turns on the other side. I am talking about one half part of the Yoke. I will tell you how later.

Quoted from tester007

Hmmm.. I am looking on the website and it says .26 dotpitch. Man...and I just sold off a bunch of these because I thought I couldn't use them...ARggghh!

Which model are you talking about ?

Quoted from tester007

Don't buy the repro deflection..it sucks.. I just sold off the two I had and went back to original. replace resistors and caps and you should have no worries.
I think I will start on theis Tovis then! I will probably use a 6100 yoke to re-wind on the Tovis yoke just to get it exact..I'll need your help on disbling G1 if I need to.

I would have to dismantled my existing working WG6100 (even if it is not perfect, I am not sure I want to take it appart). So, my solution was to use the NOS one. Why isn't that great ?

I personally would NOT use a 6100 yoke to rewind the TOVIS one, it will do you no good, buy a bunch of magnet wire size 24 (200') and strip appart the glue on top of the TOVIS yoke and then seperate both sides and the cut off in the middle all the wire and you will be ready to start winding. When you are ready, let me know I will post some pict and tell you how to do it. Keep your 6100 Yoke Intact for Pete's sake!

Trinity

PS: Do you have other interresting stuff to sell like that, Monitors, 6100 drivers....

Quoted from Trinity

Which model are you talking about ?

I think it is a mtg-1960xt..there are no markings on boxes or the frame itself. Tube is Phillips M46EJC325X100
The yoke though on it is FAR different from any yoke I have seen..don't know if it will work...

Quoted Text

I would have to dismantled my existing working WG6100 (even if it is not perfect, I am not sure I want to take it appart). So, my solution was to use the NOS one. Why isn't that great ?

Its not NOS..its a repro. Some games it cause the vectors to shake. There is supposedly a fix for it, but I don't think it is 100% and getting info out of arcadeshop is like pulling teeth..he was gonna send me the info twice..but didn't..I ended up selling them.

Quoted Text

I personally would NOT use a 6100 yoke to rewind the TOVIS one, it will do you no good, buy a bunch of magnet wire size 24 (200') and strip appart the glue on top of the TOVIS yoke and then seperate both sides and the cut off in the middle all the wire and you will be ready to start winding. When you are ready, let me know I will post some pict and tell you how to do it. Keep your 6100 Yoke Intact for Pete's sake!

Is all wire created equal? I was only wondering if there would be any impedence issues or if any wire is fine?

Quoted Text

PS: Do you have other interresting stuff to sell like that, Monitors, 6100 drivers....

I have extra monitors, not for sale though..for my test rig and/or ZVG when I get around to it.. I have HV units and deflections..yokes..but have a guy up in Edmonton with a bunch of Sega vector tubes that wants all my extra frames and parts to get those running...so all that stuff is pretty much spoken for unfortunately.

Quoted from tester007

I think it is a mtg-1960xt..there are no markings on boxes or the frame itself. Tube is Phillips M46EJC325X100
The yoke though on it is FAR different from any yoke I have seen..don't know if it will work...

Well, according to what I have seen, MTG-1960XT would be a good candidate. I have found the schematic and they look alike the MTG1902. I would have to see the picture of the YOKE to help out...

Quoted from tester007

Its not NOS..its a repro. Some games it cause the vectors to shake. There is supposedly a fix for it, but I don't think it is 100% and getting info out of arcadeshop is like pulling teeth..he was gonna send me the info twice..but didn't..I ended up selling them.

That's a pitty, me that was looking to have a full brand new setup! I guess I will have to wait and see !

Quoted from tester007

Is all wire created equal? I was only wondering if there would be any impedence issues or if any wire is fine?

Well, it is not necessary to use the old wire of a 30 year old yoke to get good results... The size of the wire is very important, if it is too small then, it is more resistive, thus slower, thus garbage image. So, JROK said #24, #24 it must be. This is what I have used and it is perfect...

Quoted from tester007

I have extra monitors, not for sale though..for my test rig and/or ZVG when I get around to it.. I have HV units and deflections..yokes..but have a guy up in Edmonton with a bunch of Sega vector tubes that wants all my extra frames and parts to get those running...so all that stuff is pretty much spoken for unfortunately.

I was just kidding, I was kinda of impressed about all the stuff you had in your hand!

Trinity

Ill get you a shot of the yoke...'very' different from anything else I have see...

Just re-do the stock deflection..not too many resistors and caps actually.. If you want a 'big' dif on your 6100's, I always find completely re-doing the neckboards makes pretty much the biggest difference of anything..at least in my experience..

Tester,

You know I was thinking... and I think the best way to find ourselves some nice monitor with .26 dot pitch would be to use a used 19' PC monitor that we find in good quantity on ebay for exemple for very cheap. I mean after that, all we need is the schematic to know how to hack into it. We could even use the Flat ones....

Anyway, is there anybody here that as a good and working 19" inches monitor for PC that would like to get rid of it for the advancement of the science and to see if we could use them as vector monitor !

Please post here or PM me. I would be glad to see if they could work, I can buy it if necessary!

Trinity

Here is the Tovis in my mame... You can see the yoke is a little more complex. Its like a bakelite or maybe thats the magnet, ring over top of the windings on the neck.

Ya..I immediately started looking at computer monitors about 4 posts ago lol! A flat monitor would be awesome but then some correction would probably need to be applied to the pcb. I 'do' have an amplifone version of a Space Duel pcb (yes it is different) that has correction applied for the different shape of the tubes (amp flatter I believe)...so we would know where to experiment.

Looks pretty impressive.  Well over my head technically.  I'm hoping one day for a cheap(ish) solution to getting a colour Mame vector game.

Quoted from tester007

Here is the Tovis in my mame... You can see the yoke is a little more complex. Its like a bakelite or maybe thats the magnet, ring over top of the windings on the neck.

Ya..I immediately started looking at computer monitors about 4 posts ago lol! A flat monitor would be awesome but then some correction would probably need to be applied to the pcb. I 'do' have an amplifone version of a Space Duel pcb (yes it is different) that has correction applied for the different shape of the tubes (amp flatter I believe)...so we would know where to experiment.

Tester,

I think they have added some stuff to remove the ringing off the Vertical/Horizontal windings. I mean, we don't have to worry to much about it. Actually there is a cover on top of the vertical yoke that should be removed and then we could see if all those windings/parts added are for the vertical part or the horizontal part. One thing for sure though is that the neck board is exactly the same at the VGA I have now.

So, are you going to do something with monitor or you would like to attack another one ?

Trinity

I could probably do one of these..I have another in the garage I was gonna use for a cocktail mame...man I had 5 of these just a while ago and was having trouble selling them for 75$ to get some space in garage...

Tester,

I think I found a place that sell some Diamond Pro 920, 19" inces Flat monitor, they sell them for $45.00 I guess it worth the effort to go pick them up and try to do something with them !

I will keep you updated about it, now... what about you... what are your plans now ?

Trinity

Got a couple more games in..up to around 25..gotta sell a couple.. Moved the garage around to make it a more workable area..took the whole weekend and still have cleaning to do...not enough shelf space for all the parts..just got a gutted battlezone as well.. Anyways...one of the additions I am pretty happy about..its quite the frankenstein right now, but I will give away the cab and keep the guts...'beautiful' 6100 in it....almost NO burn...check out

Missile Havoc!



Also got a second Gravitar I am putting the Black Widow kit into..all in all a good weekend.

ANYWAYS...I pulled off all the yokes on my busted 6100's, tossed out the tubes...Monday clean off the workbench and then set up a 6100 test rig. I will probably have time to work on this Tovis..what do you think I should do? pop off that big ring and look underneath?

Cool Pop Machine in the Background, Where did you get that??  

Did you get that part changed out OK??

Dave

Not yet..I actually took it out of the truck..but that is about it..honestly it was about 20 hours of moving stuff around and organizing over sat/sun..so no time.. I still have battlezone guts all over the inside of my truck that need to be cleaned out... I'm trying to make room for some Rock's and maybe a pin...

Hi Guys,

Just a small detail, Just to mention that it seems that the CRT tubes have not been created equal. I say that because I have connected my CGA tube to my VGA electronic and the result is quite interresting and mostly different. It seems that each board is somehow calibrated to go along a certain tube. I just don't get it why though, if I am driving the same tube, I am getting different image results... Hum...

Also, it seems that the origianl 96 turns might not be quite enough to have a sufficient deflection on the Y axis. I will do more test on this and I will keep you updated.

Trinity

Good Day Peeps!,

Because, my schedule is kinda full these days, I don't have much time to play around, so I am posting this last message about my results on my experiments:

1- At the begining, I bought 2 Monitors, 1 CGA (0.82 Dot Pitch) and 1 VGA (0.82 Dot Pictch). At that point I did not kow that they had the same Dot pitch thus the same CRT Tube.

2- Then, I start working on both. The first step was to see if I could use the already existing (vertical Part)Yoke on the Monitor, it turns out that none of the both could be saved or salvaged in any way. The reason is very simple, the Vertical Yoke needs to be very fast and if the wire is too small or the overall impedance is too big then, the image generated will be deformed. Also something that I have noted, is that the Horizontal Part of the YOKE of the CGA was arranged in series as opposed to the VGA monitor where the horizontal yoke windings were in parallel. So, if you planned on using them, the Horizontal should be arranged in parallel.

3- At this point, it was clear to me that the vertical Yoke winding needed to be redone and winded by hand (JROK info are good). The overall hand windind is not such a big problem, the point is really to come to a point where the winding is good enough to be able to converge properly, I had gread succes with my upper screen convergence but I failled to have a very good bottom screen convergence. But I guess with trial an error, I am sure I would have found a good trade off to make it work acceptably.

4- The RGB signals were another thing that I needed to figured out, I failled to see any details about that stuff in JROK page. I first thought that we could drive those signal directly to the RGB input but it did not work. the RGB signal coming out of the game board have been conditioned to drive the neck board directly and this is what I have done. In the CGA's case, it was really easy beacuse the overall design of the monitor is pretty simple. In the case of the VGA, despite the fact that the CRT dot pitch sucked big time, the neck bord was a little bit more complicated, but I did manage to make it work too. So, it ends up being not such a big deal after all.

5- So, after playing around with neck boards and hand windings yoke, even if I was getting close to have something acceptable I still had some small but anoying problems:
           - The new monitor are designed mostly with Switching regulator which means that no isolation transformer is needed. however despite the fact that Switching Reg are better in Power Transfer they remain to be a switching type regulator and in the CGA monitor case, the switching PS was switching at Horizontal Frequency 15Khz, which I am quite sure kinda brought a beating frequency in the image display. Because the CGA monitor shown a trembling and shaky image that I tried to remove with a little bit more filtering but it did not work. However, the VGA PS in that case was switching at 31K, the VGA horizontal frequency. The shakyness in the picture was quite negligeable, so in that case the VGA was a better fit. Let me remind you that in a 6100, the flyback switching frequency is 20Khz.

           - So Switching power supply was one problem, the other major problem I faced and which I admit kinda discouraged me of using either of them was the CRT dot pitch sucked tremendously. I mean 0.82 it is like a freaking big pixel. I was looking forward to use the VGA to replace my existing Tempest, but when I realized that I was kind of discouraged. It doesn't make sense to go through all that trouble for a 0.82 dot pitch. So, the solution to this problem is to use 0.27 dot pitch monitor, but those which can found very easily these days are a little bit more complicated to modify. I don't say it is not feasable, I am just saying that it might requires a little bit more precision and effort to use them. But I guess with a dot pitch 0.27 it would certainly worth the effort.

So, to concluded : What needs to be done (or needs to be careful about) in order to modify a raster monitor to a Vector monitor

1- The best would be to find a CGA monitor with a dot pitch of .26", which I think can not be found. Maybe a EGA could do the trick. Anyway, find the less complicated monitor electronic implementation possible with the best dot pitch.
2- Try to use a monitor that does not use a switching Power Supply.
3- Make sure the Horizontal Windings are in parallel (schematic can help, or if the image goes to far horizontally then, they are probably in series)
4- The RGB signals needs to drive the RGB neck board direclty. However, make sure everything is driven properly and be aware that if some grid are powered on the tube it may slow down the drawing which would give a flashy look.
5- If you don't see any image at first, you might want to play around with Flyback adjustment (not the focus, the other one )
6- Make sure your both vertical part are winded the same way with the same amonth of wire. (96 windings, see JROK page for details)
7- If you manage to find the good monitor with a good dot pitch and you get to see an image, the biggest challenge will be to come up with a Vertical arrangement that will minized the divergence problem. <- this is the biggest issue
8- If when you start the monitor and your ear your coil make a lot of noise it is because they have been arranged so one is going into opposition to the other. Like 2 magnet south pole part or 2 north pole part together, they want to get separated. In that case, you need to inverse one of the coil wiring.
9 Vertical Yoke coil should be arranged in parallel. If you can't get your image to go over the tube boundary, it is because your driver board needs its aluminum cap to be changed (4700uF/50V).

So, I think that's about it. At this point I don't forget the idea of doing it, I just don't have much time to do so. I will however try to find a suiteable monitor to try and when it will be done I will let you know guys.

Cheer!

Trinity