WG 25K7197 New Wei Ya Chassis - UPDATE: Might have just fried it

[MaxAsh]

Waiting for the components to arrive. In the meantime, I've been trying to tackle the isolation transformer situation. I mentioned previously that the output seemed high. It was suggested I test it under load to see what happened. Here are some test results, please let me know if this seems odd:

Isolation Transformer Output tests:

Zero load = 133.6 V
Hooked up 13" old CRT TV/VCR to it = 132.1 V
Hooked up TV above and a large fan = 131.2 V

Would I need a much heavier load item? Or is this proving the output is too high? Thanks for any advice, just trying to figure out if I should buy a new ISO or not.

[ed12]

120 +/- 10% =130 or 110
u olny have 1 of the secondary's loaded,so i would expect it to be a tad high

ed

[MaxAsh]

120 +/- 10% =130 or 110
u olny have 1 of the secondary's loaded,so i would expect it to be a tad high

ed

Okay, thanks ed. I just wanted to make sure before I keep going. I think I'm going to swap the Hantarex Polo 25 I have over to the MK cabinet, and then continue to work on repairing this one in the less-important Time Killers cabinet. Based on what I've read, the Hantarex Polo 25 doesn't require isolation (though I'll still rewire the MK cabinet anyway just in case). This will give me a functioning Ultimate Mortal Kombat 3, and a project with the Time Killers cabinet (which is fine, because I'm probably going to MAME it eventually anyway). Any objections to that plan? If not, I'll go with that, and come back here with advice as I work on the busted chassis.

[ed12]

no by all means get to gamming

ed

[MaxAsh]

no by all means get to gamming

ed

Swapped the Hantarex Polo 25 with the broken Wells G monitor. I've had it hooked up and running now for 30+ mins, no major issues. Two things popped up, but seem to be okay:

1) After first hooking up the monitor, the controls all went dead. That seemed really odd. I adjusted a couple of wires, thinking perhaps something was loose, and that seemed to do the trick. Strange, perhaps I bumped something. Been good ever since.

2) The image was a little off at first, but I made some adjustments. I saw some retrace lines, so I turned the brightness down. That seemed to help, but I noticed the screen will randomly "brighten" now and then, going back to the correct darkness level shortly after. I'm not sure if that's just a wobbly/dirty/lose pot for the brightness adjustment or something else. I used the flyback brightness, as the remote adjustment didn't do much.

Overall, looking good. Attached a pic for reference. Any issues, I'll update. Once I get the parts for the blown chassis, I'll come back for some advice on repairing it. Thanks!

[ed12]

u might as well add some control cleaner to your order
this way u can spray down and clean them dirty control's proper like

ed

[MaxAsh]

u might as well add some control cleaner to your order
this way u can spray down and clean them dirty control's proper like

ed

I've got some Control/Contact cleaner & lubricant spray from radio shack. It's probably 6 years old, but I doubt it expires. I'll test it out, thanks for reminding me I had it!

I noticed that the Sync pin on the RGBGrSync connector plugging into the chassis is loose. The connector pin itself is beat up/twisted from being removed and reinserted. I want to replace the connector and grab new pins, but it's expensive (shipping-wise) to order just that from mouser. The connector + pins are probably $1 or so, but the shipping is minimum $5 most places. I tried eBay, no luck so far. Anyone know where I can snag a normal 6-pin RGBGrSync connector and half dozen pins for a couple bucks? Would a local store have them? I know they often have bigger molex connectors, but I've never seen these smaller ones. If someone has a pile of connectors and pins lying around, I can paypal them a couple bucks if they'll toss 'em in an envelope 

[MaxAsh]

Ken - for reference from our conversation, see attached pics of the existing RGB connection to the chassis. I attached a shot from both sides in case you wanted to see the traces from the reverse. As you'll note, there appears to be a 6-pin position squeezed in next to the 5-pin they automatically give you. Based on the board layout, I'm assuming I remove the 5-pin and put the 6-pin I ordered in the position adjacent to it. Seems like common sense, but given that I've blown the board up once, I wanted to double check.

Thanks!

[Ken Layton]

Yes, the new 6 pin will be placed in the 6 position holes which are to the right of the 5 pin holes. The "locking ramp" of your new 6 pin header (if it has a locking ramp) will face the 3 black electrolytic capacitors directly to the left of the connector.

I would connect the harness composite sync wire to pin 5 of the new connector.

[MaxAsh]

Yes, the new 6 pin will be placed in the 6 position holes which are to the right of the 5 pin holes. The "locking ramp" of your new 6 pin header (if it has a locking ramp) will face the 3 black electrolytic capacitors directly to the left of the connector.

I would connect the harness composite sync wire to pin 5 of the new connector.

Great, thanks Ken, will do. After this I'm just waiting on one transistor that for some reason got stuck in FL for 4 days during shipping. Going to work on cleaning up the isolation transformer wiring.

My plan is to test-bench this setup this time around, instead of trying to just setup the chassis inside the cab. Aside from the AC power, isolation transformer, chassis/monitor... is there anything else I would need just to test the chassis portion? Could I essentially just set the monitor/frame/chassis on the workbench, set the power block and isolation transformer on the bench, hook it up to power, and fire it all up? The reason I ask is because the power coming from isolation to the chassis has no ground wire in this setup, meaning the only "ground" setup on the chassis/monitor will be the wire-wrap around the monitor going to the neckboard. That just seemed odd to me. Thoughts? Setup would look like this:

• AC (w/ ground) -> Isolation -> 2 wires (no ground) to chassis
• Neckboard in place with ground wire-wrap from tube on it
• Anode in place
• no ground on monitor frame

Just feels like something will be hot that I don't want in that scenario, so I welcome input, thanks. Assuming the monitor-only test goes well, I'd try it with the PCB, etc hooked up next, adding in each item one at a time.

[ed12]

all them green wire's should be your earth ground
and at least 1 of them will find it's way to the chassic of the power transformer..
as for the power supply,there will a post marked :fs:,that is the earth ground,
as to the monitor chassic that spot u posted the picture on is your earth connector point

ed

[MaxAsh]

all them green wire's should be your earth ground
and at least 1 of them will find it's way to the chassic of the power transformer..
as for the power supply,there will a post marked :fs:,that is the earth ground,
as to the monitor chassic that spot u posted the picture on is your earth connector point

ed

Hi ed - I got a little confused by your post. The power block itself is grounded of course, as are most connections in the cabinet. The power going to the chassis isn't, because the Wei Ya only has AC 2-wire coming off the board, not a 3-wire with ground. Using Ken's directions, I cut the AC cord on the chassis and added a regular 2-pin connector so I could plug it into the existing power. Here are some pictures that should help. I'm thinking the picture you're referring to was the one from post #32 in this thread, where I posted an image of a ground wire on the side of the monitor frame that was cut sometime by a previous owner? In any case, here's the setup. One pic shows the power "block" where you see the incoming AC (filter, fuses, etc under the metal casing). On top of that, bolted to the metal casing, is the transformer. I see tons of ground wires coming off the top of the metal casing, none of which go to the transformer, but the fact that the transformer is bolted to the metal casing, which is grounded, makes me thing I'm good there. The second pic shows the 2-wire power plug coming off the chassis, as well as the neckboard where I connected the monitor's wire-wrap ground strap cable.

I just thought it was weird that the chassis power has no ground, and the frame's ground wire was cut as well. I can re-wire the missing frame-to-ground connection for safety purposes. But am I okay with the incoming power to the chassis being ungrounded?

[ed12]

picture #3 is what i am refering too

>I can re-wire the missing frame-to-ground connection for safety <

just do that part
and u are gold

ed

[MaxAsh]

picture #3 is what i am refering too
>I can re-wire the missing frame-to-ground connection for safety <
just do that part
and u are gold

ed

Okay, cool, will do. Now I just stare at the mailbox until the last transistor arrives. I finished rewiring the isolation transformer to remove the marquee and switching PSU from the same output as the chassis power. I'm basically ready to test as soon as I solder on the last component. Come on mail... hurry up

[epicfatigue]

Sounds like you have two of the best people helping you with this should have it fixed in no time.

As for the light bulb in series with the fuse this is kinda what they are talking about if you want a visual this is one i built (half finished in this pic)
That does 240/110 and has a range of watt globes that can be switched between then completely cut off for quick testing i made for my little workshop.




Good luck with the repair!

[MaxAsh]

Nice, thanks for the visual!

Still waiting on the last transistor... it left FL a few days ago. In the mean time, working on the MAME build.

[chiemgau1]

Could you post some pictures of all the cabinet wiring.
I am in the same position as you are... Same monitor, same game, same cabinet just a nba jam setup at the moment.
Just need to get the monitor chassis and set up the wiring to work for UMK3.

So I'm following your posts.
Thanks

[MaxAsh]

Could you post some pictures of all the cabinet wiring.
I am in the same position as you are... Same monitor, same game, same cabinet just a nba jam setup at the moment.
Just need to get the monitor chassis and set up the wiring to work for UMK3.

So I'm following your posts.
Thanks

Do you mean the corrected wiring (changing the transformer to normal isolation setup) or the original Midway cabinet wiring? If you mean the original, I posted a diagram from the service manual a ways back in the thread. If you mean the way I re-wired it, I basically just removed the Marquee Light and Switching PSU from the transformer output terminals and changed them to direct from AC. I can draw up a sketch, which would be cleaner than the pics of the actual wiring, if that would help. Let me know.

[MaxAsh]

UPDATE: I finished replacing the friend components on the Wei Ya chassis. After some thorough pre-hookup testing, I went ahead and setup everything on a test bench and gave it a try.

First, the good news: It powered on, and the game displayed on the screen immediately. Looked good too, better than my original attempt before the chassis blew. No sync issues either.

Now the worrisome news: I think something is about to go again, so I turned it off. Looking for some thoughts/advice. Here's what happened...

I left it running and continued to observe and check heat levels on components. Last time it blew, I felt a large amount of heat coming off the tall white resistor (25W, 140ohm). I smelled "burning" and then that resistor cracked/blew and produced an ominous white cloud. This time, that resistor is nice and cool, no issues, looking good. Unfortunately, the resistor immediately next to it (labeled 5W 2.2ohmJ) is giving off a LOT of heat, and is very hot to the touch. I'm starting to smell a similar scent to the one I did previously when I lost the larger resistor. I shut everything down as a precaution. Should I just fire it up again and let it run, see if something cooks? I let it go for 4 minutes before the heat seemed too high and I started to catch a smell. Last time, when the big one blew, it was after about 5-7 minutes of running time.

Thoughts? I know some heat on a resistor is okay, but I can't keep my finger on it for more than a second or so without having to remove it, which sounds hotter than I'm used to feeling on a resistor. See attached pic of the resistor.

Quick Edit: Tested power at chassis, still showing around 131 V while running. I know previous replies said this is okay, but we're certain that's not cooking things?

[chiemgau1]

Could you post some pictures of all the cabinet wiring.
I am in the same position as you are... Same monitor, same game, same cabinet just a nba jam setup at the moment.
Just need to get the monitor chassis and set up the wiring to work for UMK3.

So I'm following your posts.
Thanks

Do you mean the corrected wiring (changing the transformer to normal isolation setup) or the original Midway cabinet wiring? If you mean the original, I posted a diagram from the service manual a ways back in the thread. If you mean the way I re-wired it, I basically just removed the Marquee Light and Switching PSU from the transformer output terminals and changed them to direct from AC. I can draw up a sketch, which would be cleaner than the pics of the actual wiring, if that would help. Let me know.

The cabinet I have is NBA Jam but most of the wiring has been removed. The tube from the monitor with no chassis the power supply wiring as well as the iso transformer are still hooked up but that's about it. So I was just wondering if you could post a few pics of the inside because I want to see how it's wired up. I got the wiring for the joysticks and buttons from the machine the UMK3 board come out of but it's a mess right now. Thanks

[MaxAsh]

Sure, I can pop it open and take some pics of various wiring sections.

Anyone have feedback on the last post I made about the overheating 5W resistor?

[MK3FAN]

Sure, I can pop it open and take some pics of various wiring sections.

Anyone have feedback on the last post I made about the overheating 5W resistor?

Glad you got it running again. As for your overheating resistor, it might be normal. There are some resistors on the K7000 that get extremely hot also. I forget, are you running this chassis through an isolation transformer? If so, is it funtioning and hooked up properly?

[MaxAsh]

Glad you got it running again. As for your overheating resistor, it might be normal. There are some resistors on the K7000 that get extremely hot also. I forget, are you running this chassis through an isolation transformer? If so, is it funtioning and hooked up properly?

It appears to be an isolation transformer, but for whatever reason midway used to wire them so the switching power supply, marquee light, and monitor all came of the same side. I re-wired it so the light and switching power supply are coming off the AC power/ filter area instead, and just the monitor chassis is on the transformer now. Both cabinets I have are wired this way, and both seem to output around 131V on the transformer output. I'm told this is because back when they were manufactured, household current wasn't consistently 120V range like it is today?

I tested the transformer using instructions I found online, which basically tested to make sure no DC current was coming through, and normal transformer functionality was indicated by the tests.

So that resistor being really hot, and starting to smell, is okay? It sure smelled like burning to me, which happened just before the big resistor blew. Maybe I'm just paranoid?

[MK3FAN]

Hell, is shouldn't be melting of course but a lot of times, the factory puts a coating on those resistors and the smell is the coating being burned off. In my personal opinion, I'd say you're probably ok using it.

[MaxAsh]

I guess I could just leave it running and cross my fingers. Last time it made it a little over 5 minutes. So far I've gone 4 minutes since I replaced the blown components, smelled bad things/felt heat and shut it down. I guess at this point, worst case it blows again. Technically, I don't "need" the monitor since I swapped the Hantarex I had into the UMK3 cabinet, and then converted the cabinet I pulled it from into a MAME with LCD.

Basically, I have a monitor/chassis on my work bench hooked up to a Time Killers PCB that I don't really need. Ideally I'd sell it, or better keep it for another cabinet project. So... I guess if it blows, I just call it a day. Deep down I just don't want to admit I may have wasted $95 on a chassis, I want to see that thing work like a charm and feel good about it. After you blow it once, you want it to work the second time haha. Well... maybe I'll give it a try. Gulp.

[Ken Layton]

I'm looking at the power supply section of a schematic to a model 825 Wei-Ya. The 2.2 ohm 5 watt resistor is connected in series with the 140 ohm 25 watt resistor. Looks to me like it's supposed to get hot.

[MaxAsh]

Okay, Thanks Ken and MK3fan, I guess it's time to go for it. I've done everything recommended and tested everything suggested. I'll plug it all in and let it ride. I'll let everyone know how it goes.

Thanks to all for the advice and assistance! Either way, regardless of if this works, you've all been awesome.

[boostin4hp]

I have the same configuration and problem with sync. Did you ever get this running again and fix the sync issue?

[MaxAsh]

I have the same configuration and problem with sync. Did you ever get this running again and fix the sync issue?

I haven't had a chance to set it up and let it run to see if it has another meltdown. Part of me has been avoiding it, but mostly I've just been busy working on another project. As for the Sync issues, I'm guessing you're referring to something from earlier in the thread. The two things that fixed it were:

1) Americanize the Wei Ya Chassis (search for Ken Layton's post on it, very informative). One of the key points from that process is changing out the Wei Ya's 5-pin RGBGrSync connection for a standard 6-pin one.

2) Making sure my sync pin was in the correct place. The game I had, for whatever reason, had the sync pin setup for pin 5 instead of pin 6. I just had to move it to the other position to fix the sync issues.

Hope that helps! I'll report back when I setup my test bench and try out the chassis/monitor again for a full, long-term test.

[MaxAsh]

Good news, followed by some seemingly very bad news:

Setup everything on the test bench, wired it all up, turned on the game. Looked excellent, colors, brightness, you name it, perfect. Ran it for just over 2 hours to ensure it was working great, no issues. I proceeded to mount everything, making sure it was all properly wired, hooked up, etc. Plugged in the cabinet, turned in on, worked great. Ran it for about 10 minutes, no issues. This is where things suddenly went bad:

My back is to the screen as I'm looking at something else and I hear what sounds like "scrambling". Not sure if you know what I mean, but basically that sound a CRT TV/Monitor makes when the image suddenly goes all wacky. I turn around and see that the image is basically a wash of rainbow colors, no coherent image. Looks all crazy for unknown reasons. I attempt a couple of adjustments, nothing helps, so I turn it off. I checked everything, looked okay, so I turned it back on. This time the screen stays almost completely dark. There's not "static" on the screen when I touch it like usual, but I have neckglow. Every 30 seconds or so, I see a little flicker of light randomly on the screen, then blackness again. Nothing appears to have blown this time, but I'm back to a dead screen. No idea what I did or what went wrong. After 2+ hours of great functionality, I'm at a loss. Ugh.

[grantspain]

disconnect your video signal and then turn the screen volts adjustment on the flyback and hopefully you will get a raster,if you do get a raster then the issue will be related to power supply dc voltages or your game board

[MaxAsh]

disconnect your video signal and then turn the screen volts adjustment on the flyback and hopefully you will get a raster,if you do get a raster then the issue will be related to power supply dc voltages or your game board

Game works perfectly on another monitor, but I'll go give that a try and report back thanks

[adidas1984x]

any updates??

[MaxAsh]

any updates??

Sadly I've had zero luck after the monitor died a second time. Really frustrating to go through everything, get it working for a couple of hours, then suddenly have it go out again. I'm fairly certain the original crash and burn was because of the incorrectly setup isolation transformer the cabinet had in place. The second was probably a damaged or weakened component from the first blowout that didn't get replaced in my fix. Not really sure.

I've put it off to the side to give me space to work on several other arcade-related projects. I sold the UMK3 cabinet with a different 25" monitor in it, so I don't have UMK3 to test it on anymore. I do have a Street Fighter II World Warrior... not sure if there would be an issue using a 25" monitor with that? If it would work, I could try testing on that too when I have time.