Installing Wei-ya Chassis in Hantarex Polo - Help!

[jrbean]

I am replacing a 25" Hantarex Polo chassis with a Wei-ya 826HR chassis. The monitor was nonfunctional before I started, but I was assured when I purchased it that it had worked recently (FWIW).

With all of the documentation out there, It really was pretty straightforward to hook it all up, but when I powered it on, the monitor was dark, and I got a wisp of white smoke drifting up from the 2 tall white resistors adjacent to the fuses. I quickly unplugged it, but am now unsure what to do. I don't see anything obviously burned, but it looks like it was the white plastic on the resistors smoking.

*Could I have the A/C wired reversed? The wires coming from my iso transformer are Purple and Purple/Yellow. I wasn't sure which was which (and didn't think it mattered), so I just picked one. Currently, Purple/Yellow is connected to '+'.

*I was just wanting to do a smoke test, so I didn't have anything driving the inputs -- can that cause a problem?

*Any ideas how to proceed? What to check?

Thanks,
John

[Ken Layton]

Here's your problem: The Polo doesn't use an isolation transformer for power. The Wei-ya 826 requires an isolation transformer. You probably have damaged the power supply section of the Wei-ya immediately when you powered it up.

[jrbean]

Hmm...the interesting thing is that this cabinet (an NBA JAM) has both a Hantarex Polo and an isolation transformer. Both were covered in the same grimy/smoky residue, so I'm assuming that both have been in the cabinet for quite some time.

I was under the impression after reading some of the other posts that while the transformer was not required for all monitors, that it could be used for all monitors to protect against miswired power. Is that not the case?

Thanks,
John

[Ken Layton]

Oh, I didn't see that it already had one.

Well the next thing to check then is the yoke specs. The Polo yoke has these specs and wire colors:

Vertical section is red & brown wires with a dc resistance of 5.4 ohms. Horizontal section is yellow & orange wires with a dc resistance of 1.7 ohms.

I do not have any specs for the yoke requirements of the Wei-ya 826, but I kinda think the Polo yoke resistance is lower than what the Wei-ya needs. I can't find any specs on the 826 chassis even on Wei-ya's site.

[jrbean]

On the tube, I'm able to measure 5.8 ohm vertical, and 1.5 ohm horizontal.

The Wei-Ya chassis is rated for 9.6 ohm vertical, and 1.3 ohm horizontal. I was under the impression from reading some other posts (ok--maybe I read too much) that when it was that close, it was adjustable using the H/V pots or by tweaking the H/V circuit itself.

As a test, I completely unplugged the tube from the chassis, and powered it on. I got the same result--white smoke drifting up from the vicinity of the power supply after 20 sec (actually seems to be the plastic covering R740 and/or R804).

What are the chances I got a bad chassis board?

John

[Ken Layton]

The yoke you have is nearly half the resistance the Wei-ya is looking for which means a big difference in current draw from the monitor. I'd say you may have damaged the chassis. In this case your better option might have been the Jen Shinn chassis from 8liners as I think it will work with that low of a resistance.

[Kevin Mullins]

Can you throw a pic of what you are calling an isolation transformer up here for us to see?

Just curious as to if it really is an isolation transformer and not just a power supply type transformer.

[jrbean]

Sure! This is what is in the chassis:



I measure 135V AC across the Purple and Purple/Yellow wires, and rougly half that from either Purple wire to the green wire.

One other point that Mr. Layton's note reminded me of is that when I first turned on the power, I'm sure I saw one of the fuses glowing out of the corner of my eye. By the time I looked back, it wasn't glowing anymore (and is not blown). I guess that goes back to his proposal that I damaged something when I turned it on the first time.

Are there typical things that blow when you do this sort of thing? Should I call back Alva Amusements to see if they can help?

This has been typical of my experiences with this cabinet--I've already given up on the original chassis board, after failing to repair it with a cap kit and new flyback transformer. Now I'm thinking that I should just punt and order a whole monitor...

John

[jrbean]

I guess my other alternative would be to start over with an 8liners chassis.

I've never seen this monitor function--Is there any way to know that the tube is ok, or even worthwhile to put another $100 in?

I can see that there is some burn-in. It is enough that I can read "Insert Coin" at the top of the screen.

Thanks!
John

[Ken Layton]

I see the problem. I saw this very same thing last month. Midway in their infinite stupidity wired everything that's 120 volt powered to the SECONDARY of that isolation transformer thus defeating it's purpose. They wired the monitor, game power supply, light fixture, and dollar bill acceptor (if so equipped) to the output of the isolation transformer. That's a big no-no. Look at the "Power Wiring Diagram" in the Mortal Kombat 2 manual and you'll see what I mean. The person that designed that should be shot because that's a serious shock hazard!

It wouldn't have hurt anything with the original POLO monitor because it didn't need isolation, but it does make a difference with the Wei-ya model you have since it DOES need isolation.

[Ken Layton]

I measure 135V AC across the Purple and Purple/Yellow wires, and rougly half that from either Purple wire to the green wire.

Whoa! That's screwy. For one thing that's too high of voltage coming out of the transformer. Are the voltage setting jumper wires in that 15 pin connector configured to your local voltage standards? There's a 115 volt and a 132 volt setting in the way the jumpers are set in that connector to choose the correct voltage.

Measuring the voltage from the purple and purple/yellow is the correct wires to use. That voltage reading from either the purple or purple/yellow to green ground tells me the isolation transformer is electrically leaking voltage and is in an UNSAFE condition.

[jrbean]

Just a quick followup question....

Since I don't know whether the problem that caused the destruction of my new chassis board was related to the tube or the "isolation" transformer, I'm considering just pitching the whole mess and replacing it with a Wei-Ya 25" monitor and a new isolation transformer.

This is actually my 2nd attempt at fixing this monitor--in my first attempt I installed a new cap kit and flyback transformer (with the result being a *dead* chassis board. Because of this, I'm hesitant to throw more money at a tube that has obvious burn-in, especially when Alva Amusement is selling new monitors for $200+shipping.

Am I likely to run into issues mounting it into my chassis, or are these 25" chassis fairly standardized?

Any other issues I should consider?  I am going to be driving it with an ArcadeVGA and amplifier.

Thanks!
John

[Ken Layton]

Remember that the purpose of the isolation transformer is to 'isolate' the monitor from everything else. Be sure that only the monitor is connected to the output of the isolation transformer.

As to mounting concerns, the only problems I run across is that even though the bolt holes in the 'universal' type of mounting frame generally are standard from brand-to-brand and model-to-model, it's the bent bars that hold the circuit board to the frame that are never in the same place as the monitor you're replacing. This almost always involves driling new holes and moving those bars so the monitor fits the cabinet. I had to do this on a Dynamo cabinet when I replaced a Hantarex with a Wells-Gardner.

[jrbean]

Just a quick note to follow up on this thread...I ended up replacing the Hantarex Polo 25 with a Wei-Ya 825HR monitor from Alva Amusements.



See lots of pictures of the montor in my pbase gallery:
http://www.pbase.com/jrbean/arcade

So far, so good. It powered up with my original NBA JAM iso transformer, and seems to be working ok. I still have some adjustments to do--looks like I have a bit of rotation, some of the colors are a bit too yellow, and the edges aren't as in-focus as the center of the screen.  Overall, a pretty good deal.

Fit-wise, the one thing to note is that this tube is a good 1-2" smaller in width and height than the Polo I replaced, and it is quite a bit flatter. I had to make some adapter brackets to mount the monitor, and the face now fits inside the bezel, instead of the bezel covering the overscan area.

John