Trying to identify what monitor I have

marcdavis

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All,

Try to be gentle as this is my first venture into video game realm and I think I am in over my head.

I am trying to figure out what someone did to a Gauntlet Legends arcade that I got at auction. This should use a medium resolution 27" monitor by the manuals I have found. I have not measured the monitor yet but I think it is still a 27" since there is not much gap to the side of the cabinet but the Vegas I/O board has the dip switches set to Standard Resolution. (SW1 OFF) The chassis has some masking tape on some of the metal heat sink (I say heat sink may be a something else) that says K7400, a date, and "good". The chassis board has stamped P763 in one corner. I have tried to match pictures of the K7400 and K7500 chassis pictures and they look too similar to me right now for me to tell.

Could someone have kept the tube and replaced the chassis to be a K7400? or would the tube have needed to be replaced also? Are there any markings that I can go by to identify what I have in here to start with? Like what resolution tube is in here and what chassis is installed.

Thanks for the help,
Marc Davis
 
7400 = standard res

7400 is a standard res monitor, the tube is the same between standard res and medium res. If it is marked 7400 and the switches are on standard res I think you have a 7400 but give us some pictures especially of the neck board if you want us to tell you.
 
The chassis board has stamped P763 in one corner. I have tried to match pictures of the K7400 and K7500 chassis pictures and they look too similar to me right now for me to tell.

P763 is a K7400 chassis.

Could someone have kept the tube and replaced the chassis to be a K7400? or would the tube have needed to be replaced also? Are there any markings that I can go by to identify what I have in here to start with? Like what resolution tube is in here and what chassis is installed.

the tube is the same between standard res and medium res.

The tube is the same, but the yoke is not. the yoke for the 7400 can be used with a U2000 (standard-res) or U5000 (dual-res), but NOT a k7500. if in doubt, read the number on the label on the yoke and post it here. A K7400 yoke should be labeled 9A2988-1...
 
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Sorry as I was writing the original I realized I would need pictures.

By yoke you mean the magnets and coil section attaching to the CRT correct. (Sorry new to most of this terminology) I tried to get a picture of the only labels I see on the yoke. I believe it says PJ3051 and AT6027/20.

Hopefully those pictures help. If a better picture needs taking of something let me know and I will try to take the picture. I did not include the remote adjustment board picture but I took one of that just in case it is needed. It says P790 and only has 7 adjustments.

Marc Davis
 

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Definitely a 7400 - 25" chassis it seems since there is no pincushion board. Before we get too much into things, what problem are you having with the monitor?

1) Neckboard looks like a new replacement.

2) Caps look like they need to be replaced on main chassis.

3) Yoke may not be the right one, but you can measure the ohms on the windings to see if it's compatible...
 
The issues I have been having is trying to keep the focus and convergence. When I got it I had to use the focus on the flyback to get the white into focus. The white seems to stay in focus most of the time. The red at times can be way out of focus then the next time we turn it on the boot up messages (Text is in red) are not readable.

I think I need to work on the convergence as when I go into test mode on the white screen the I think I am seeing red up and to the left on the whole screen. But also I don't think I have a complete test screen as at least one side I believe right does not have the final borders.

Also when in the purity for the colors test patterns to me the left side always seems darker.

During game play it just seems at time to be blurry and not very crisp. To my son he says it is not a problem and just wants to play.

I measured the tube and it is definately a 27" so could the problem be that it has the 25" neck board? or am I measuring wrong and if it had a 25" neck board the screen would not even come on if it had a 27" CRT?

Eventually I would like to get this back to the correct medium resolution monitor. So that sounds like I need a whole new chassis, neck board, and maybe yoke. That is sounding like a more longterm goal though at this point.

I guess if I am going to keep this one for now I should re-cap the chassis as I saw some of the same stuff most likely of what look like caps blowing out the bottom onto the board so figure that needs doing. Does any of the focus/convergence sound like the flyback needs replacing also?

Marc Davis
 
Sorry to bump this older thread but can someone confirm this is a K7400 variant? Also, it has a 2nd set of pins identical to the input connector... do these chassis do dual-res?

K7400.jpg


EDIT: Actually ... I think that there be a U2000?
 
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it is one of the variants, but hard to tell which from the angle of the pic. Looks like the horizontal width coil is by the HOT, which would mean a standard-res U2000.

The dual-res U5000 would have two sets of headers in the center back with a connector to move between them...
 
it is one of the variants, but hard to tell which from the angle of the pic. Looks like the horizontal width coil is by the HOT, which would mean a standard-res U2000.

The dual-res U5000 would have two sets of headers in the center back with a connector to move between them...

There is a 5-pin molex connector next to the copper coil looking thing (not the width coil) in the picture to the left... middle of the board...behind the large brown component (resister?)

That is it.
 
P717 is a U2000 chassis. Other than that, I'd need to see better pics to determine what you are talking about. Some of the variants have a molex connector behind the remote cable connector for the purpose of installing a pincushion board, but it has more than 5 pins...
 
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