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Author Topic: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...  (Read 7424 times)

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sjbaines

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Hi everyone,
I've been lurking for quite a while now, but I've decided that I've now done enough up-front design on my first MAME cab that it's time to share some renders and get some feedback...

I'm going for a stand-up cab with a rotating 21" CRT computer monitor (kindly donated by Franco B - thanks!), and I'm intending to have a semi-modular control panel. 
I'm going with a computer monitor over an arcade one because I like the old vector games and I want to be able to play them without them looking awful. (I'm happy that a hi-res raster CRT can fake being a low-res raster CRT much better than a low-res raster CRT can fake being a vector monitor.)
And I'm going with a CRT over an LCD, becuase I don't like the look of LCDs.

So, first off a general view of what I'm thinking at the moment:

Dark cab, blue illuminated cp. Not decided what to do art-wise yet. Very much liked Ghost in the Machine, and might try something simular for vector art. Or, I might go for a mimimalist approach, and have a plain panel like in the render.
For the marquee, I'm planning illuminated space invaders, but I've not done a render of that yet.
One reason for going for lighting over printed art is that it means that when the machine is off, it all goes black, and is less intrusive (since it's going to be in a family area...

Next, here's a shot showing the machine in its designated alcove. Fitting it in there puts some size/shape constraints on the cab.


Looking down at the cp:


Now the rotation support assembly:

Since it's quite a heavy CRT, the mechanism is quite beefy. I'm using some big rubber wheeled castors for the main supports,
and some smaller nylon ones to stop the whole thing moving forwards or backwards (you can just see the back ones in this image).
In theory the monitor will never try to go forwards, but I want to make sure that the monitor stays put, so they are in there. Also, by pressing back on the top of the rear monitor support wheel they will also make sure that it doesn't lift up - there being no space in the cab for top-rear castors to do this.

Another view of the rotation assembly:

Some of the smaller front-back support wheels are visible. The top shelf is shorter than the bottom one, and a different design at the top, due to space constraints.

I'm intending to build this rotation assembly first, so that if it ends up being a nightmare, I can scrap the idea without having to rework the cab. Assuming all goes well, this will be a self-contained assembly, which I can then just slide into the cab frame as a single unit onto support rails attached to the cab sides. The thought of trying to assemble it and align it within a cabinet didn't appeal...

Side view showing the fairly tight fit of the monitor plus rotator:

Proportions still look a little off to me - cp too high?
(I'm very tall (6'4"), and I want this thing to be comfortable to play, so I'm still struggling with this a bit.)

The 'semi-modular' control panel, showing centre section removed:

My plan here is to have the joysticks and buttons fixed, and to have a replaceable centre section for specialist controls.
The standard option shown for the centre section is a spinner, because I'm keen on Tempest...
I've sized the centre panel so that it would hold a trackball, and of course other panels could be analoge sticks, etc.

Since most games use sticks and buttons, I decided they should be permanent. This also means that the front-end can rely on them always being there, so that simplifies that.

I'm thinking of having the centre panels pressing on one or more of a set of hidden microswitches, so that each panel effectively has a different binary id, so the front end knows which panel is plugged in.

I'm going to use a uHID for input, and a LedWiz for driving the LEDs.
For monitor rotation I'm going to use a car window motor, driven by a H-bridge, under parallel port control, as discussed in this excellent thread: http://forum.arcadecontrols.com/index.php?topic=94350.0

I'm going with a 'controls in use light up' plan, and in theory, the blue rings around the spinner and sticks are also included in that.
In practice though, I don't know if I'm realistically going to be able to make them... (For the sticks I've gone for Seimitsu LS-32-01, which have an S-plate for mounting in wooden panels. However, once I've routed out the space for them, and allowed for a perspex cp cover, I'm only going to have a few mm thickness of wood left, so squeezing a lighting arrangement into that might be tough...).

Anyway, this is what I've got now, I'd be interested in hearing any thoughts, since at this stage most things can still be changed.

   Cheers - Steve



javeryh

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #1 on: December 14, 2010, 09:25:16 pm »
Woah - are you going to automate the rotation?  Can't wait to see that.  Looks good so far!

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #2 on: December 15, 2010, 04:39:47 pm »
Hi,
Woah - are you going to automate the rotation?  Can't wait to see that.  Looks good so far!
Yes, automatic rotation is the plan. MALA, plus the software in the thread I quoted, provides all that's needed for software control - at least I think it does!

Originally I was going to have a button or switch to rotate the monitor, and then get the front end to update itself and games lists to match the current orientation whenever the orientation was changed.

But then it occured to me that a cleaner solution was to create two top-level game lists, one for Horizontal, and one for Vertical.
That way, any game can be selected, and the front end will rotate the monitor to match _if needed_, BUT because the lists are sorted by orientation,
a rotation will only actually be needed when you switch from one list to another.

Now, if you play the same set of games in the same order, the number of monitor rotations needed is the same whichever way it is done.
BUT, by sorting the lists like this, you'll be browsing the list corresponding to the current orientation by default, so you are more likely to spot a game in that same list to play next.  If you want to play one from the other orientation, just switch to that list in the front end.

This also means that you can browse the lists for both orientations without anything changing - rotation will only happen when you choose to start a game, so there should never be any rotations that weren't needed.



    Cheers - Steve

HaRuMaN

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #3 on: December 15, 2010, 04:46:32 pm »
Will you have an auto-degauss function as well?

opt2not

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #4 on: December 15, 2010, 05:09:32 pm »
Nice concepts. It's been a while since any new rotatable-monitor projects have been posted here. Good luck! Most people have problems getting figuring out a solution for enough torque to rotate a CRT. Here's to hoping you've got a decent motor solution.  :cheers:

Donkbaca

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #5 on: December 15, 2010, 05:59:55 pm »
Hey I am going to try the illuminated Marquee thing too.  I was thinking about etching the back of some smoked plexiglass, then painting the area behind it black and then edge lighting the marquee.  I am hoping that when the lights are off its looks like a flat black surface and then when the lights are on it would look cool, like the design is just hovering in space.

My only concerns are:
1) The cab is going to be awfully heavy with all that extra hardware in there.  Make sure you plan accordingly!

2) the biggest challenge, from what I have seen, with regards to rotating displays is how to make the bezel look right.  Are you going to have a circular bezel?

3) I respect the anti-franken panel notion of a modualr CP.  but, I have yet to see what that looks right.  I know one ting others have done is use cat 5 cable to plug and play modular panels, though I am not sure how succesful it is.  I say just keep the spinner and ditch the modular idea.  Where are you going to keep the modular panels?  And it would seem like a pain to have to constantly swap out pieces. 

I am not trying to be negative, just giving you my thoughts...

I love the look of the cab though.  keep us updated

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #6 on: December 15, 2010, 06:56:51 pm »
Will you have an auto-degauss function as well?
Yes - the mrotate2 software from DaOld Man provides software support for a degauss signal, so I'll trigger usung that.
One thought I did have though - whether it would be possible to avoid the need for degauss via a software trick...
When I tip the monitor on it's side the colours shift in a predictable way. If I could get the graphics card to use a custom colour table, I wonder whether the colour shifts can be removed in software and so avoid the need to degauss..?

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #7 on: December 15, 2010, 07:01:08 pm »
Nice concepts. It's been a while since any new rotatable-monitor projects have been posted here. Good luck! Most people have problems getting figuring out a solution for enough torque to rotate a CRT. Here's to hoping you've got a decent motor solution.  :cheers:

Thanks!  The motor I'm planning to use is from a car electric window, and it's got a worm drive on it,
So I'm pretty confident it'll have the torque - though of course I won't know for sure till I build this.
Of course, you can always trade torque for speed by changing the gearing.

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #8 on: December 16, 2010, 05:55:38 am »
Hey I am going to try the illuminated Marquee thing too.  I was thinking about etching the back of some smoked plexiglass, then painting the area behind it black and then edge lighting the marquee.  I am hoping that when the lights are off its looks like a flat black surface and then when the lights are on it would look cool, like the design is just hovering in space.
The 'Ghost in the Machine' cab does that kind of thing on the cp - very nice it looks too.
I was planning on conventional backlighting for the marque but still with the dark Perspex on the front so it's all dark when switched off. OR, possibly somthing using EL-wire, though I believe that fades relatively quickly...
I'll do a render or two soon showing what I have in mind.

Quote
My only concerns are:
1) The cab is going to be awfully heavy with all that extra hardware in there.  Make sure you plan accordingly!
Yes - and potentially top-heavy at that. As you say, I'll have to be careful. If there's any danger whatsoever that the completed thing could topple then I'll put more weight in the bottom. I'll probably also hook it to an eye in the wall behind, just to be extra safe - especially since there's a 3-year old in the house who might try climbing up it...

Strength-wise I think it should be fine - I'm going to use 3/4" MDF for the sides (probably 1/2" for all the other pieces), and all the weight of the the monitor assembly will be hanging directly off the cab sides.

Quote
2) the biggest challenge, from what I have seen, with regards to rotating displays is how to make the bezel look right.  Are you going to have a circular bezel?
Not certain yet. If you look at the side view render - the monitor (which has a completely flat tube front) is  right up against the front glass, so whatever it is, it will have to be thin.  I'm intending to have slightly tinted perspex as a cover over the screen, so if I mask off the rest of the inside of the cab, then the image will hopefully just float there.
So, yes, I'll probably have a circular bezel, but it probably won't be visible behind the cover glass anyway.
I may or may not have some subtle art in the corners, haven't decided yet.

Quote
3) I respect the anti-franken panel notion of a modualr CP.  but, I have yet to see what that looks right.  I know one ting others have done is use cat 5 cable to plug and play modular panels, though I am not sure how succesful it is.  I say just keep the spinner and ditch the modular idea.
From the electronics pov, I don't think there's a problem, I'll just need to connectorise some of the LedWiz/uHID connections. As you say, cat 5 plugs and sockets seem quite a good approach. Since most of my panel will be fixed, this wouldn't be a big job as I'd only be doing it for a handful of connections (and using a uHID means that the connections don't even need to be the same type - i.e. analogue, switch, or optical can all share the same lines, since the uHID can be reprogrammed on the fly when a panel is replaced).
I guess I'm reluctant to lose the option to be able to use other controllers, BUT it would be simpler and realistically the panel would look cleaner as a single unit. I'll give it some more thought.
Of course, the cp is one part of the cab that could be replaced later fairly easily, so maybe for version 1 I should go for the fixed panel - and then see how much I miss the games I can't play. I can always rebuild the CP later.

Quote
Where are you going to keep the modular panels?  And it would seem like a pain to have to constantly swap out pieces. 
Probably inside the cab. I deliberately kept the modular bit relatively small (just big enough for a 3" trackball).
Given that I'm not going for an 'everything under the sun' fixed panel, I guess it comes down to what's the bigger inconvenience - not being able to play certain games at all, or having to swap a panel to play those games.

Quote
I am not trying to be negative, just giving you my thoughts...
No problem - thoughts are what I'm after!  I've not done this before, and lots of people here have, so I'm open to suggestions, and if anyone thinks I'm doing something wrong, I'd rather know about it so I can make an informed choice of whether to make a change or not.

Quote
I love the look of the cab though.  keep us updated
Thanks, will do.


jipp

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #9 on: December 16, 2010, 01:33:22 pm »
looks great.  look forward to the build.

chris.

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #10 on: December 16, 2010, 01:42:13 pm »
Will you have an auto-degauss function as well?
Yes - the mrotate2 software from DaOld Man provides software support for a degauss signal, so I'll trigger usung that.
One thought I did have though - whether it would be possible to avoid the need for degauss via a software trick...
When I tip the monitor on it's side the colours shift in a predictable way. If I could get the graphics card to use a custom colour table, I wonder whether the colour shifts can be removed in software and so avoid the need to degauss..?

Hmm.  I doubt that you could do that...  but I've been wrong before, so who knows?  I would think the auto-degauss in in the mrotate2 would a far less complex solution.

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #11 on: December 16, 2010, 08:25:24 pm »
Alright! Another rotating monitor project.
I like your design, and am looking forward to seeing it take shape.
About your degauss question:
Most CRT monitors will automatically degauss on power up, so if you use the Mrotate2 function to turn the monitor off while rotating, the monitor may degauss when Mrotate2 turns it back on.
If so, the degauss circuit may not even be necessary.
Its an easy test, with monitor turned on, turn the monitor on its side, see if the colors mess up, if so, just turn it off then back on. I bet it will degauss and straighten out the colors.
Good luck with your project, and just to give you a sneak peek, I am just about finished with MRotate3.
I was thinking; I can program it to just turn off the monitor then turn it back on, at the end of rotation.
This will allow you to leave the monitor on, yet degauss it by cycling power at end of rotation.
What do you think?

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #12 on: December 17, 2010, 07:36:09 pm »
Hmm.  I doubt that you could do that...  but I've been wrong before, so who knows?  I would think the auto-degauss in in the mrotate2 would a far less complex solution.

I'm planning to go for the degauss approach, because that definately works, and there's enough complexity in this design already.

I do think there is potential in the colour fiddling approach though. As long as the colours change consistently, and I don't see why they wouldn't, then it just comes down to whether you can get the gfx card to remap the colours. I've not looked into it, but I do think it could work. Anyway, it's something I could experiment with later, and if it does work then I can switch to using that approach. It's certainly a big unknown though, so for now I'm not going to persue it.

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #13 on: December 17, 2010, 07:51:17 pm »
DaOld Man - hello!
Alright! Another rotating monitor project.
I like your design, and am looking forward to seeing it take shape.
Thanks - quite pleased with the reaction so far.
Quote
About your degauss question:
Most CRT monitors will automatically degauss on power up, so if you use the Mrotate2 function to turn the monitor off while rotating, the monitor may degauss when Mrotate2 turns it back on.
If so, the degauss circuit may not even be necessary.
Its an easy test, with monitor turned on, turn the monitor on its side, see if the colors mess up, if so, just turn it off then back on. I bet it will degauss and straighten out the colors.
Yes, the colours are screwed with the monitor rotated, and power cycling does trigger degauss and fixes it.

I need to re-read your thread again to remind myself of all the options you explorede, but ultimately I either need to trigger the degauss circuit, or cycle the power, after a rotation. Although cycling the power is simpler to rig up, I'm inclined to go for triggering the degauss directly because:
1. It's less stress on the monitor (maybe insignificant - I don't know, I'm not a monitor expert).
2. Display remains active throughout.

Quote
Good luck with your project, and just to give you a sneak peek, I am just about finished with MRotate3.
Thank you, and interested to see what's new in MRotate3...

Quote
I was thinking; I can program it to just turn off the monitor then turn it back on, at the end of rotation.
This will allow you to leave the monitor on, yet degauss it by cycling power at end of rotation.
What do you think?
I think I need to re-read your original thread, and remind myself of the details, but options are always good!

If you mean rotate, then power off-on, then I guess there's a question of how long it should be off for the monitor to actually trigger the degauss when turned back on (I'm guessing that there's a cap somewhere that discharges when monitor is off, and when you turn it on again, the lack of charge on the cap is the signal to trigger the degauss?).

Anyway, once I've reminded myself of the details of the mrotate2 options, I'll post again here, or pm you.

   Cheers - Steve

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #14 on: December 17, 2010, 08:51:05 pm »
Sounds good. There are a lot of guys on here that are monitor experts, I am not, but from what I have learned from this forum, Im pretty sure the degauss is on a thermal switch, that needs a few minutes to cool down before it will allow degauss again.
I think I will go ahead and program the option to pulse the monitor off/on after rotation in Mrotate3. This will leave the display active while rotating. The off/on pulse will happen when the monitor is finished rotating and the motor drive is turned off, and user can set how long to leave the monitor turned off. (I am thinking between 1-30 seconds). Of course like all other options, it does not have to be used, plus user will still have the degauss option as it is now.
Anyway, I will post on here when Mrotate3 is ready.
I will be following this thread, if I can help in any way, I will be glad to.

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #15 on: December 18, 2010, 05:44:20 am »
Sounds good. There are a lot of guys on here that are monitor experts, I am not, but from what I have learned from this forum, Im pretty sure the degauss is on a thermal switch, that needs a few minutes to cool down before it will allow degauss again.
Ok, so thermal switch prevents excessive deguaussing, but separate to that there must be some minimum off-on time such that the monitor tries to trigger degauss when switched back on.  E.g. if the monitor was only switched off for say 1/10th sec, would it try to degauss, or not? I'm guessing that that choice is based on charge on a capacitor, and is likely to result in a different time for different monitors.

Quote
on power up the monitor presumebaly always tries to trigger the degauss, but if the thermal switch is still too hot then nothing will happen. So, the amount of time the I think I will go ahead and program the option to pulse the monitor off/on after rotation in Mrotate3. This will leave the display active while rotating. The off/on pulse will happen when the monitor is finished rotating and the motor drive is turned off, and user can set how long to leave the monitor turned off. (I am thinking between 1-30 seconds). Of course like all other options, it does not have to be used, plus user will still have the degauss option as it is now.
Anyway, I will post on here when Mrotate3 is ready.
That sounds great.
Quote
I will be following this thread, if I can help in any way, I will be glad to.
Thanks very much.

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #16 on: December 18, 2010, 06:17:49 am »
So - if you rotate the monitor twice quickly, then the second degauss may not fire because of the thermal cutout.
Fine, that protects the monitor, but it does mean that the colours are still broken. 
But even once the thermal cutout has cooled and degauss could now happen, nothing would happen because another degauss signal needs to be sent, but the cab doesn't know it.

Unless there's some additional way to retrigger the degauss, then the only way to get the colours right again would be to rotate back to original orientation (which would needlessly trigger another degauss), then wait for the thermal cutout to cool, then rotate back again.

However, there is another possibility:
If you know what the minimum allowed interval between degausses is, then mrotate could make sure that it always enforces that interval.

E.g. each time it is about to trigger degauss, it could:
1. Read timestamp file for last degauss
2. Compare time with current system time to find time since last degauss
3. Wait for however long is needed
4. Actually trigger degauss
5. Update timestamp file.
6. Done

Since the time taken for the thermal cutout to cool is going to vary, then even this still wouldn't provide any guarantee, but it would be more robust than just triggering as soon as rotation finishes, and it would only delay triggering the degauss in situations where not waiting means that the degauss woudn't happen.

What do you think, DaOld Man?


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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #17 on: December 18, 2010, 08:35:37 am »
Ok, that option will be included in MRotate3.
You could also add a button somewhere on your cab (like on top or in the back), that you could press in case the mentioned scenario happens. The button could turn on the relay that MRotate does when it degausses.
I think it would just require a diode and a N.O. button, attached to a +5VDC supply (computer power).
Of course doing it auto magically would be much cooler.

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #18 on: December 18, 2010, 11:16:23 am »
Ok, that option will be included in MRotate3.
Excellent - thanks very much.

Quote
You could also add a button somewhere on your cab (like on top or in the back), that you could press in case the mentioned scenario happens. The button could turn on the relay that MRotate does when it degausses.
I think it would just require a diode and a N.O. button, attached to a +5VDC supply (computer power).
That's true, but if the need for the button can be avoided, that's better still.

Quote
Of course doing it auto magically would be much cooler.
Indeed.

Having a system that does everything automatically - unless you change orientatation twice quickly - in which case you have to press a hidden button, feels like a bit of a bodge...

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #19 on: December 18, 2010, 01:43:46 pm »
i think it would be a good idea.  lets face it anything mechanical can break down.. and would you rather have to tear it apart to manually fix the issue when a hidden button could do the work for you.

i understand you would like something more, but seems like a logical safety feature to me.

but none the less good luck in whatever you do.
chris.

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #20 on: December 18, 2010, 03:11:07 pm »
i think it would be a good idea.  lets face it anything mechanical can break down.. and would you rather have to tear it apart to manually fix the issue when a hidden button could do the work for you.

i understand you would like something more, but seems like a logical safety feature to me.

but none the less good luck in whatever you do.
chris.

Hi Chris,
I assume you mean adding a manual degauss button?

It's not a safety feature, it's a convenience feature. If the degauss is prevented by the thermal cut-out (which IS a safety feature), then all that happens is that the colours remain messed up - so nothing in any way dangerous. If this happens, you don't need to open the cab, you just need to trigger the rotation back and forth again.
Now, that itself is an irritation, which is why I want to try and automate around this situation happening - but if the automatics fail (e.g. if the delay isn't actually long enough), then nothing terrible will happen.  If mrotate3 can enforce the delay, then there should never be a need for manual degaussing. If the software crashes, the cab will need a reboot anyway, which will degauss again on startup.

You're quite right though that mechanical things can/will break down/jam, etc.

Because of this, and since there's going to be a fairly beefy motor, and heavy rotating things in the cab then I'm planning the following safety features:
1. Fuses in the motor supply (silly not to, really).
2. Microswitch limit switches which physically cut the motor power when rotation reaches the limits, rather than relying on software shut off.
3. A hidden (but easy to press in a hurry!) kill switch, which will kill power to the entire cabinet instantly. I know the PC won't like it, but if you can see/hear that the rotation mechanism has jammed or is straining then you want to be able to kill power quickly, rather than waiting for fuses to blow (which they might not).
4. An interlock on the cab door(s), which will kill power to the motor, so no rotation can happen whilst the cab is open.
(MAYBE kill power to the whole cab, but I think that's not actually a good idea. It would basically mean no access to the PC whilst the cab is powered up.
Since all the huge voltage stuff is cased, and I may well need to get at the PC sometimes, I think just killing motor power makes sense. Incidentally, the monitor will be out of its original plastic casing, but still fully enclosed in its internal cage.)
5. I'm considering adding a bunch of other microswitches which are arranged so that one or more will be triggered if the rotating assembly moves out of line. Again, if any of these trip then power to the whole cab would be killed instantly.

It might all seem like overkill, but for the sake of a bit more wiring and a few more (relatively cheap) components, I think it's well worth it for the increased safety against electrical or mechanical faults.

   Cheers - Steve

jipp

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #21 on: December 18, 2010, 07:13:08 pm »
Hi, i miss understood.  i follow.  over kill maybe.. peace of mind.. priceless :)

chris

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #22 on: December 23, 2010, 05:03:57 pm »
  Hi Steve,
I just want to add my 50 cent for your project. I did something similar. You can see this on my small blog about my MameCab. It is in german but the pictures tell a lot. The interesting part is, that I try the same as you try: set a CTR inside a piece of wood, set them on wheels and try to rotate. My version wont work:
1st try was to use a frame of copper tubing - but it always jump out of the wheels
2nd try was to cut a round wood plate and center the CRT inside, but this also jump out of the steering wheels. Always remeber that the CRT is not vertical, it has a small angle and don't underestimat the weight of the monitor and the power of gravity.
3rd try was a success (like you can see on the blog http://daddelraum.blogspot.com/2009/03/der-monitor-soll-sich-doch-drehen.html) I got a hint from an other member of a german arcade forum and I use a empty bicycle rim to place the CRT inside. And this worked perfect for me.

I like you're idea about using the rotate3 for the mame. I decide against, because the rotation was slow and I don't wan't to rotate the monitor all the time. To going around the color problem during rotation i physically switched the monitor off during the turn. You can see the wiring and the turning on the monitor on this blog page http://daddelraum.blogspot.com/2009/03/relaisschalter-motorsteuerung_22.html

I build inside the cab on the upper left three buttons. One for the Power on/off (yes it send the power switch to the basic linux system and initiate a init 0) and one to rotate into landscape and one for going into upright mode.

cheers and a merry Xmas to you
Dirk

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #23 on: December 24, 2010, 05:58:44 am »
Hi Dirk,
  Hi Steve,
I just want to add my 50 cent for your project. I did something similar.
Thanks for posting - interesting to see variations on this idea.
I did consider using a bike wheel rim, but couldn't find one the right size. I've got very little spare space, since the cab can't get any wider or it won't fit into the alcove in the room it is going in. This leaves very little clearance between the monitor and the cab sides, so the 'wheel' has to be a very exact size.

It looks like you are supporting the entire CRT using a single wheel?
In my design there are two, (one at front, one at back) so the weight is supported across them, and there shouldn't be any twisting forces trying to pull the wheel out of position, so I'm hoping it won't be inclined to 'jump out'.

You say that rotation is very slow, and I notice that you are using a small pinion on the drive motor (which looks very similar to the one I've got). Have you tried putting a larger pinion on so that it drives faster?

BTW, I'm going to have to modify my design anyway, as I've just noticed (and I don't know how on earth I failed to notice before) that where I've got some of the front/back castors means that they will foul the monitor tube half-way through rotation...
On the plus side, the revised design will make some other things simpler.  I'll post again when I've updated the model.

Happy Christmas!


sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #24 on: January 04, 2011, 05:43:12 pm »
A small update now holidays are out of the way.

I've tweaked the design of the rotating monitor support:




Nothing now clashes, and there's more scope for adjustments.

Also, In this design, I've added a third disk to the back, which will be the one driven by the rotation motor.
The benefit of this over driving one of the other two wheels is that I can set the diameter to set the
rotation speed, and the drive mechanism is out of the way of the rest of the assembly.

Anyway, I think I've done enough planning on the mechanical bits of this section, so next steps for this are to get
a some wood supplies, and start cutting...

So, I need to make my decision between MDF or Plywood.  I was going to go with MDF, but several people have
strongly recommended ply instead, so I'm still unsure.
Unfortunately, the ply at my local wood supply place looks pretty poor quality, so if I do go for ply then I need
to find somewhere I can order from that I can trust to ship me decent quality material...

More later.




DaOld Man

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #25 on: January 04, 2011, 06:26:32 pm »
I made the discs for my rotating monitor out of 3/4" MDF.
I used CPVC glue and smeared it all around the outside edges of the mdf discs, this strengthened it so the MDF edge doesnt bend or dent any at all against the bearings I used. I used roller skate bearings, which are a lot smaller diameter that the caster wheels in your plan, so you should not have as much weight bearing against the edge of the disc, as I did. (More surface area on the casters should result in less force against the edge of the disc.)

EDIT: link to my rotating monitor project:

http://forum.arcadecontrols.com/index.php?topic=72750.160
« Last Edit: January 04, 2011, 06:28:50 pm by DaOld Man »

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #26 on: January 04, 2011, 07:05:26 pm »
I made the discs for my rotating monitor out of 3/4" MDF.
I used CPVC glue and smeared it all around the outside edges of the mdf discs, this strengthened it so the MDF edge doesnt bend or dent any at all against the bearings I used. I used roller skate bearings, which are a lot smaller diameter that the caster wheels in your plan, so you should not have as much weight bearing against the edge of the disc, as I did. (More surface area on the casters should result in less force against the edge of the disc.)
I was considering whether to put any sort of rim on the disks to toughen up the edges, especially if I do end up using ply.
The castors that will be taking the load are 3" diameter (the renders have them to scale) with hard rubber tyres, so not likely to damage the wood, so maybe not needed.
Your idea of a glue coating sounds quite good.

For a harder wearing surface, I was wondering about using a length of T-Molding.

Quote
EDIT: link to my rotating monitor project:
http://forum.arcadecontrols.com/index.php?topic=72750.160
Thanks - I've had a quick skim, and looks to be lots of useful stuff in there, so I'll go back and have a proper read.
Cheers.


DaOld Man

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #27 on: January 04, 2011, 07:44:19 pm »
I was more worried about the MDF coming apart on the edge, since it puts off so much dust when cutting it. The glue seems to add a "crust" to the edge, I havent seen any dust at all coming from the edge during rotating.
Using T-molding might be a good idea, as long as it can hold up. With 3" diameter bearings, i doubt if you will need anything.
Im not too sure about the plywood, I did use it for the front and back frame, but you have to think about the monitor, which is a lot of weight, and the area of contact against the bearings. There is a lot of force in those areas, and rotating could bring out some weak areas of the disc.
I thought long and hard about MDF, but so far it has worked out good. (But I would definitely seal the edge with glue.)

And second thought about t-molding, the slot you would have to cut in the MDF would take out a considerable portion of the meat, so it could make it weaker. (Also may create a fault line which the forces may try to push apart).I would definitely seal the edge with glue first, then cut the T-molding slot after glue has sucked up in the MDF and dried.
This project is very interesting. Please take pics of your progress, and good luck.

jipp

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #28 on: January 05, 2011, 06:21:44 am »
very cool project old man.    you went all out with the plugins too.. very cool.. love this hobbie.

lots of inspiration for you to use to make this happen.  if it was me i would use plywood for the wheel tho.  just me.  but if you glue the edges maybe it would be stronger than plywood?

look forward to watching this unfold.. even tho i doubt ill ever have the skill set to make such a cab.

chris.

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #29 on: January 05, 2011, 06:53:41 am »
Good luck with the project buddy, I know how heavy that mo fo of a monitor is!  ;D

 :cheers:

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #30 on: January 05, 2011, 04:26:56 pm »
Good luck with the project buddy, I know how heavy that mo fo of a monitor is!  ;D

 :cheers:
Yeah, it's quite a biggy... Thanks for donating it though - it's the ideal size for what I'm trying to do.

   Cheers - Steve

D_Harris

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #31 on: January 05, 2011, 05:12:00 pm »
I didn't read through this whole thread, but a few years ago I created a rotating monitor support for one of my Donkey Kong cabinets that required one to pull the monitor out through the front, rotate it, and then push it back.

There was very little tolerance and the whole degaussing issue was a pain.

Darren Harris
Staten Island, New York.
My collection:Asteroids, Joust, Millipede, Ms. Pac-man, Pole Position, Robotron 2084, Star Trek, Star Wars, and 100+ PCBs. Trading/Selling:Arkanoid: R.O.D. Cocktail, Sanyo 20EZ, Hewlett Packard 16500A Logic Analysis System with Accessories. Wanted:Mach 3 joystick. Millipede Trackball. MVS 4-slot PCB. 100 or WG4600 monitor Tube.

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #32 on: January 27, 2011, 12:03:54 pm »
Some progress:

After agonising over what type of wood to go for, I finally made a choice, and I'm now in possession of:
1. Three sheets of 18mm hardwood ply for the cab itself (which seems to have an extremely thin veneer (maybe 0.1mm?) of some reddish wood - don't know what it actually is?
2. One sheet of 18mm MDF for the control panel, monitor rotation disks, and any other generally fiddly bits.
3. Lots of 25x25mm and 25x38mm strip for internal bracing.

I've also finished designing a H-Bridge based motor control circuit and corresponding stripboard layout, and
the postman delivered big box of assorted electronics this morning, so the soldering starts this evening!

Pictures soon...
« Last Edit: February 05, 2011, 08:45:28 pm by sjbaines »

sjbaines

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #33 on: February 05, 2011, 08:43:17 pm »
I finally finished putting together my DIY interface/motor drive circuit for the monitor rotation motor.
After spending ages checking and checking and checking, finally had the courage to hook it up to the parallel port
and an external power supply, and switch it on... and...  nothing exploded! Not only that, but it works properly!
Yay - victory is mine!

Picture time:

This is the interface board itself:
(BTW, just to be crystal clear - it does NOT have mains connected to it - I'm just using 2-core mains cable to connect the motor power supply and the motor itself)
It is built on 0.1" stripboard, and is based around an L298N 'Dual H-Bridge' chip, with both bridges connected in parallel to increase the current handling*

The connector on the left is for the power connections: Ground, 5V for the logic, and 12V for the motor*

The L298N is to the right of the connector. It's in a package that doesn't directly fit the 0.1" grid spacing of the stripboard, but some gentle persuation makes it go in.

Below that is the motor power output connector (middle terminal is unused), surrounded by rather chunky Schottky diodes to prevent a voltage spike when the motor is turned off.

To the right is a Quad 2-input And gate (74HC08) used to add some safety logic to the system, basically by switching the motor off when the appropriate limit switch is pressed,
even if the external control inputs are telling it to keep turning.

The connector near top-centre is connected to the two limit switches. One pin is at 5V, and is connected to common on the two switches. The other two pins are connected to the NC (normally closed)
connections on the microswitches. I wired them up this way around so that a bad connection to the limit switch (or not having them connected at all) is interpreted as 'switch pressed', and switches off the motor.

The final two connectors on the right are connected to the parallel port. The top one has a ground connection, and connections for the two limit switch status signals. The cluster of resistors is required to
safely interface the limit switches with the parallel port.
Finally, the bottom right connector carries the control signals from the computer - Enable, Clockwise, and Anti-clockwise. The Clockwise and Anti-clockwise control signals and ANDed with the corresponding limit switch state before being passed to the H-Bridge. This prevents the motor from being asked to rotate beyond its limits, even if the software is asking it to. In normal operation, the software sees the limit switches trigger, and stops asking the motor to rotate, but I didn't want to have to rely on the software.


This just shows the connection to the parallel port. I actually used a spare network patch cable and cut the ends off, to give me an 8-core cable. I'm currently using 6 of the wires, and expect to use one more to trigger degauss.
(still need to shrink the heat-shrink - I didn't want to do it until I was certain it was all wired up correctly!)


And here we have the improvised test-setup! The motor is a used electric window motor off eBay. It's got a worm drive on the output, so it's got loads of torque, and I'm pretty confident that it'll be able to haul the monitor around.
For the moment though - all it needs to move is a biro which I've crudely attached to the motor output so that it presses on the limit switches which are themselves crudely attached to the motor housing.
It looks messy (and it is), but it was good enough to test the motor drive.


Safety features:
1. Limit switches stop motor rotation regardless of computer command.
2. Bad connection to a limit switch is seen as that switch being pressed - hence motor stops.
3. If limit switches are not plugged in then motor will not move (same reason as 2)
4. If the top connection to the computer isn't connected then the computer won't know the state of the limit switches, but 1. above will prevent any damage being done.
5. If the lower connection to the computer isn't connected, then computer commands can't reach the board, but in this case the enable signal is pulled to ground, disabling the motor.

There will also be an off-board fuse in the 12V supply line, as an extra level of insurance, in case the motor jams for any reason.

That's all for now. If people are interested then I'll post the stripboard layout and schematic (I need to update them both a little to reflect some last minute changes I put on the board).

It's greate to be making some progress at last!

   Cheers - Steve

*For testing, I've been running the motor at low voltage to keep the current down. I still need to add some more conductors to the high current paths on the back of the board before I run it at full power,
otherwise the stripboard is likely to burn out...


drventure

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #34 on: February 05, 2011, 09:56:04 pm »
Nicely done!

Can't wait to see the monitor rotating

DaOld Man

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Re: First Cab concepts - Rotating CRT monitor, Semi-Modular control panel...
« Reply #35 on: February 06, 2011, 12:17:31 am »
Sweet!!

And +1 on what drventure said.

DaOld Man

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Any updates on this project?

sjbaines

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Wow, have two months really gone by since my last post?
As usual, other things have got in the way and slowed progress down a lot, but I am actively working on it.
Haven't got time (working!) to upload any pics at the moment, but progress is:

1. Degaussing
I found a point in the monitor wiring where there's a logic line which turns degauss circuit on,
so I've spliced a couple of diodes into that cable to make a crude OR-gate,
so that the monitor will degauss either when it normally would (internally triggered), or when it
gets a logic high from outside (i.e. mRotate triggered). Needs a bit more work, but concept proven.

2. Mechanical mounting
This is where I've been spending most of the time I've been working on this.
I've cut 23" diameter MDF disks, then made cutouts for the decased monitor to fit inside.
I spent a lot of time on this, because it was critical to get the measurements (and cutting) right.
Also, the front disk has a cutout which in the corners goes almost to the edge of the disk.
I wasn't at all convinced that the disk would be strong enough, so I then cut additional slots into
which I put strips of metal and lots of expoxy resin to fill the gaps. The cutting for this was especially
fiddly because in places there were only a few mm of material left...
Monitor is now (permanently, I hope) embedded in the front support disk, and the rear one should be attached tonight.

I've got pictures, I'll try to upload some tonight...





« Last Edit: March 29, 2011, 10:07:55 am by sjbaines »

sjbaines

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And now another year has flown by...

This post is just to state that this project is now dead.  :(

Basically what happened is that I started hanging around on the Jamma+ forum,
and got less interested in making a MAME cab, and more interested in collecting
a few classic cabs instead...

The only part that got completed was mounting the monitor in a rotating frame,
and I've posted in the free stuff thread to try to give that away.

It's kind of sad, because I was originally really enthusiastic about doing this,
but as I got more into dedicated cabs, I really couldn't see myself actually
using this cab much, so I decided to abandon it.

  
 

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