Introduction

Got a broken arcade monitor? Maybe you're just tired of searching for an decent-looking display and don't have the dough to shell out for a new (and extremely heavy) Betson Imperial or Wells-Gardner D9200. If you already have monitor with minimal burn-in, you can save a ton of money by simply replacing the chassis (monitor guts) instead of buying a whole new display.

The following article will outline the steps involved in replacing the chassis of a 25” Hantarex Polo arcade monitor, with a new one from 8liners. 'Polos are a common display found in many Midway and Capcom cabinets, including the Mortal Kombat, Killer Instinct, NFL Blitz, and Street Fighter line of games. The one used here was removed from a non-working MK 3 cab and was determined to be the perfect candidate for an 8liner swap due to a very crispy chassis that needed more than just a few capacitors replaced!

This tutorial should give you an idea as to the level of difficulty and skill involved in making such an installation. If you have a moderate understanding of electronics and are relatively handy, this just might be the project for you. In addition, if you have a larger or smaller display than what I used, many (if not all) of the steps can be used as a guideline in replacing a different chassis than the one I used. Just email the folks at 8liners.com and see if they have any tips or suggestions. It should be fairly simple for them to determine which replacement board is right for your tube and what additional measures (if necessary) will be needed.

Here are the specs of the 8Liners board I used:

Specifications :

DEFLECTION YOKE MATCHING IMPEDANCE :
HORIZONTAL :
LH 1.9 MH
RH ~2.2 OHM
VERTICAL :
LV 116 MH
RV~ 54.4 OHM, RV ~13 OHM
INPUT VOLTAGE : AC 110 VAC 50/60 HZ
POWER CONSUMPTION : 50 WATTS
INPUT SIGNAL : R.G.B POSITIVE POLARITY 2.5~5.0VPP
SYNC SIGNAL : H/V COMPOSITE NEGATIVE 2.5~5.0VPP
MATCH SOCKET : 1.2,3,4
H-FREQUENCY : 15 KHZ
V-FREQUENCY : 60 HZ
BANDWIDTH : 8 MHZ
CONNECTOR : 5 PIN (R.G.B,GND,SYNC)
DIMENSION(mm) : L265×W200×H130
WEIGHT : 1.5 KGS/PC
PACKING : 12 PCS PER CARTON(N.W 19 KG G.W 22 KG)
PER CARTON : L63×W49×H53 CM

-Disclaimers-

1. Though I may refer to 8Liners.com in several places throughout this article, I am in no way affiliated, related to, or being compensated by the proprietor(s) or personnel of this establishment for this tutorial. Some of the information in this article is borrowed from the 8liners.com website, but are edited or expanded upon for clarity and simplicity.

2. The following procedures require a fair amount of knowledge in electronics, good physical condition, and a HUGE amount of common sense. If you lack even ONE of these traits, please don't attempt any of the following procedures. Neither I, nor any other reference cited in this article are responsible for any injuries/damages that occur as a result of your actions. So please, don't be stupid.

What you get

OK. So you bit the bullet and bought a new chassis from 8Liners. What can you expect when you open the box?

8-Liners Chassis as Shipped

The Chassis Unpacked

* Monitor chassis w/ neck board and 110v power cord attached (sorry, no 230v models available)
* Remote cable bundle
* RGB input cables
* Degaussing wire
* Braided grounding cable
* Horizontal/Vertical wire bundle

Getting Started

Before we begin, there are a few things you'll need besides the new 8Liners kit in order to install it safely and thoroughly:

Tools lined up and ready to go

* Digital Multimeter (or continuity tester)
* Assorted socket set with drivers
* Flat-head (--) and Phillips (+) screwdrivers
* Pencil, grease pen, or permanent marker
* Suitable work area
* Discharge tool*
* 5 BLUE terminal crimp connectors (tube or spade-style)

*If you are unable to locate a commercial discharge tool, you can make one out of a length of wire, 2 alligator clips, and a long-handled (insulated) screwdriver. Read on for instructions.

Discharging

Before going any further, you'll need discharge the monitor (using the discharge tool) by attaching the clamp to the monitor's metal frame and inserting the tip under the anode cap. If you are unfamiliar with the dangers involved in discharging a CRT, I highly suggest you read up on the the subject. Getting zapped by 20,000 volts would not be the best start an otherwise fun project. Below are a few good links to demonstrate how to discharge a monitor safely. Check 'em out:

http://www.instantarcade.com/discharge.php

http://www.arcadegames.net/sightsound/discharge.ppt

http://www.stickycarpet.com/pinx/md.html

**Remember**

1. Unplug the monitor from the wall
2. Use a long handled screwdriver with an insulated handle or commercial discharge tool
3. Keep the alligator clip as close to the tip of the screwdriver (away from you) as possible
4. Put one hand in your pocket to ensure you don't accidentally touch a hot circuit
5. Remove all watches, rings and other jewelery
6. Pause for one minute after the first discharge and then discharge again. Repeat this 2 more times to ensure the tube is completely discharged before removing the anode cap (suction cup).

Removing the Tube

After you've successfully discharged the monitor, mark out its relative position with either a heavy pencil, grease pen, or permanent marker against the support brackets inside the cabinet . This will allow you to later place the monitor in the same position you removed it from, helping eliminate any bezel/positioning problems.

Marking the postion of the monitor now will save you time later

Use a socket driver and remove the 4 machine nuts holding the monitor in place while an assistant presses on the face of the tube to keep it from falling forward. Remove the monitor by pulling it straight out and put it on your work area.*

As easy as one...

two...

three...

*An alternate method of removal would be to lay the cabinet on its back, remove the 4 nuts, and lift it up and out. Be careful though, a 25” monitor weighs roughly 110 lbs, (50 kg), so use proper lifting techniques!

Taking out the Chassis

Once you have the monitor out and on a suitable work surface, disconnect the following from the chassis:

* Power cable
* RGB cable
* Remote Adjustment (Input signal) connector
* Horizontal/Vertical connectors
* Neck board
* Earth rail connector (on neck board)
* Degaussing wire

Take out the 4 retention screws and carefully remove neck board from the tube. Lift the chassis from the frame.

Install the 8liners board

Place the new 8liners chassis where the old one was. Note its differences in size and mounting points. Secure it to the frame by drilling 2 small holes in the plastic along the rear and thread in the old screws where the chassis used to mount. This should be enough to keep it from moving around and sliding anywhere, but if you still don't feel this is secure enough, you can make 2 more holes along the front edge and run Zip-Ties around the frame to hold it in place.

Connecting all the wires

To connect the chassis to a degaussing source, the easiest solution is to use the one already wrapped around the tube. To adapt it to the new chassis, simply clip both connectors off and splice the new one onto the old wire. Connect the cable to the chassis.

Carefully attach the neck board to the tube. Work it in gently as to not stress the glass to much. Enough pressure here can crack the neck and destroy your tube by equalizing the vacuum stored inside.

Next we need to attach the braided ground wire that wraps around behind the tube to the neck board. Because the original monitor used a spade-type connector, and the neck board uses a post, you can make your own connector instead of running a new ground by taking a blue insulated terminal connector and crimping it to the end of your existing braided ground wire. This works out perfectly since the diameter of the crimp connector is the same as the post and makes for a snug fit. Its cheap, easy, and saves a trip to the hardware store.

Note: If your crimp connector doesn't fit very well, give it a light squeeze with a pair of pliers to make it grip better.

Recap

Up to this point you should have the chassis mounted and secured, the degaussing wire connected to the chassis, and the earth rail (braided wire) connected to its post on the neck board. You should now be left with 3 cable sets; the RGB (video), horizontal/vertical cables, and remote connector bundles. The RGB and remote connectors are fairly simple to hook up since they are the only connectors left and have unique fittings. The horizontal/vertical cables will require a little extra attention, but we'll get to those in a moment.

Seat the remote connector and RGB cables in their places as shown in the picture.

Attention to detail

Next we'll be attaching the horizontal and vertical signal cables to their respective posts on the yoke. It's actually a very simple process, but requires some extra attention if you want to get it done right the first time.

If the little white connectors on the old chassis are still in good condition, you may be able to salvage and reuse them here. Unfortunately, this monitor's original connectors were brittle and cracked making them unsuitable for reuse.

To see how good your crimping skills are, take a digital multimeter (or continuity tester) and set it to “Ohms”. If it has an audible function that sounds a tone when it detects resistance, enable it. Test your crimp job by inserting one of the multimeter leads into the cable connector's red wire terminal, and the other lead into your new crimp connector at the other end. You should either get a noticeable resistance load or hear a tone from your multimeter signifying continuity. If not, check your crimp job and test it again. Repeat for the 3 remaining wires.

Now connect the “factory” end of the H/V cable to the chassis. Notice that there are 2 sets of pins on the chassis that would accept this connector. If you are performing this on a 25” Hantarex Polo, you must use the post set shown in the picture (the one to the right). If you are unsure which one to use, contact the guys at 8Liners.com and ask them for clarification.

Finally, attach the anode cap (thick wire w/ sucker on the end) to the tube (you might have to give the cap a squeeze to help the metal prongs seat properly). Once you've done that, go over all your connections and ensure they are seated securely.

Congratulations! You've just replaced a monitor chassis. Now wire up your RGB cable and start tweaking the display.