JK Cabinet to MAME - Arcade project Part II!

CRT MONITOR

The type of monitor CRT - Cathode Ray Tube that were in my JK Cabinet had lost colors in the picture and needed to be replaced. This is because the cabinet has been turned on for many hours every day, year after year, which result in a decrease of brightness and color in the monitor picture. The reasons why the monitor's picture will be poor may be many, for example dried out electrolytic capacitors on the monitor chassis board or other electronic components which are obsolete. Another reason may be that the magnetic rings (purity/covergence rings) located on the monitor tube may be affected, with the result that it has started to become demagnetized. My CRT monitor has the brand Samsung with size 25 "(inches).

The picture above also shows the original Bezel used to cover the areas that are outside the monitor's picture glass.

There are new produced CRT monitors 29 "(inch) available on the market that are suitable for arcade games but they are expensive since they are imported from the USA, which was not an economical option in my case.

!!! WARNING !!!

The alternative was to start debug the monitor and its chassis board but since there are high levels of voltage up to 25000 volts, it is not something that a person without a license or experience should do. It may be associated with DANGER OF LIFE touching the wrong details on the monitor case or the chassis board even though the voltage to the cabinet is unplugged, even after electrical power is disconnected to the cabinet high levels of residual chages can be present in the monitor and associated parts up to a year afterwards.

Dell P1130 Trinitron 21"

My choice was to replace the old CRT monitor with a used computer monitor of the brand Dell P1130 Trinitron 21 "(inches) at a cost of SEK 500. Which means that the picture area is reduced by 4" which will probably be marginally to the overall gaming experience. However, instead will the Trinitron technology from Sony give a picture which is incredibly sharp with vivid colors. The flatter tube minimizes reflections in the picture area and straight lines remain straight from all viewing angles. A highly appreciated monitor by companies using CAD/CAM/CAE.

Another major advantage of a computer screen as opposed to the older CRT monitors is that you can play both vertical and horizontal games on them. The older CRT monitors you need to turn 90 degrees when you change from a horizontal to a vertical game.

To get the computer monitor in the cabinet I had to remove the plastic housing by loosening the screws on the back and bottom of the casing.

The casing snaps apart at the top with the help of a couple of screwdrivers.

Then the housing cover can be removed from the "front frame" which forms part of the plastic casing.

Happ! - Plastic housing is now split.

Then "front frame" is screwed away from the front of the computer screen.

The upper bracket (marked with a green ring) and the bottom bracket will be used to attach the computer screen inside the cabinet whith help of support consoles.

Now is the "frame" loose and lies in front of the computer screen, there is a circuit board inside the "frame" and on the outside there are buttons which control the strength of color and brightness. The front frame will be used with the computer screen when it is mounted in the cabinet and serve as bezel. Bezel is a black paper covering the surfaces that are outside the screen to give a clean look inside the cabinet.

Some pictures on the computer screen without plastic casing. Please note computer monitor brackets that can be seen in the green rings in the picture, the computer monitor brackets will be bolted to the brackets inside the cabinet.

NEW BRACKETS

The old CRT monitor was suspended in brackets in the cabinet. To get the computer screen into the cabinet new brackets are made by angle brackets. First I make a paper template by holding it against the brackets on the computer screen. A lot of measuring is done to know how much of the angle bracket that needs to be cut off.

By using the paper template a black line is drawn on the angle bracket to mark where to cut.

Angle bracket after cutting.

In the picture we see an angle bracket mounted to the monitor too se how it works.

Angle brackets mounted in the cabinet. To take up tolerances between the cabinet and the computer monitor the holes in the brackets was made oval by using a round file, highlighted green in the picture.

OUT WITH THE OLD AND IN WITH THE NEW

Time to clean out the cabinet. After CRT monitor is dismounted from the cabinet, chassis card, power supply and JAMMA board are removed to make room for the "new" computer monitor and the computer.

The space is limited and it is heavy to lift in and out a monitor from an arcade game, but to facilitate it is possible to unscrew the rod of wood that sits in JK Cabinet that the glass rests on. A monitor weighs anywhere from 20 to 30 kg so watch your back!!!

Now is the computer monitor in place inside the JK Cabinet and in the picture we can see the screws holding the computer monitor in place against angle brackets.

It became very well and a new bezel need to be made to cover the area around screen.

Finally, a picture showing the front. The computer fits just below the computer monitor.

ARCADE CABINET BEZEL

Bezel - is a frame that is cut out of cardboard to cover the area around the monitor. I bought a sheet of black cardboard carton at the bookstore that I felt had the right rigidity to carry itself around the monitor, bezel set around the monitor on the consoles.

To get the outside dimensions I drew of the old frame (bezel) on the cardboard carton.

After some measurements around the monitor in the cabinet, I drew a inner frame to be cut out.

Here is the outer edge and the inner frame cutout in the cardboard carton.

Bezel fitted perfectly around the monitor.

A picture when MaLA is loading.

A picture of MaLa screen.

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