MK2 cab has sound and monitor issues

bigbadmiker

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Hi,


I need some professional help with my MK2 cab. There is feedback coming from my speakers even when the sound is off. It sounds like a high pitched hiss. I messed around with the speaker wires but that didn't help.


Also, I've adjusted my monitor as best as I could, but there seems to be a problem with the vertical adjustment. I can't get it to increase enough. There's about an inch at the bottom of the screen that I can't get it to reach. When I adjust the v-size, it increases to a point and then starts to decrease. I'm not sure if this is normal. Here's some pictures. I've also got some issue with lines in the screen at the top, but most of them go away after a few minutes of being on. You can see the green line at the bottom of screen and at the top in some of the pictures.

Any advice is appreciated. Thanks.

http://s1012.photobucket.com/albums/af248/bigbadmiker/
 
Update: Now I can't move the picture to the top inch of the screen either. So there's an inch at the bottom and at the top that I can't adjust the monitor to cover.
 
sounds like this one will need a cap kit after all. :/

if you're any good with a soldering iron though, it's not hard. just time consuming to make sure you install the caps with the proper polarity.

only time it gets interesting is when it's a chassis that has lifting traces or the solder pads just fall off. :) (happened on a few WG monitors I've capped)
 
Okay, so a cap kit will fix the vertical problem then? At least there's a solution now. And what about those lines in the screen? Maybe I'll get lucky and it will take care of those too. I don't know if I'm brave enough to do a cap kit myself. I've never done it. I'm also a novice solderer...lol. I think it's the removing of the chassis that is going to be a pita. And I've never removed a chassis...but I've discharged a monitor. I guess that's a start. Got to learn this shit at some point, right? Thanks for the help.
 
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(1990s Midway cabinet lesson ahead:)

unfortunately, the only real way to work on monitors in Midway cabs like these is to take the monitor completely out. it's not rocket science... just dig out a 7/16" socket, preferably use an extension for your ratchet, and undo the 4 nuts that hold the monitor frame in. a 7/16" wrench can do too.

oh, forgot about the retaining clip (it's either going to be the original phillips head bolts or in the case of my KI cab, potentially modified with 1/4" hex head screws lol) and then you have to lift up on the glass to get it out of the wood retainer, slide that down, then take the plastic bezel out... then you can unbolt the monitor. :)

take note of disconnecting the video signal cable (the RGB one that comes off the JAMMA connector), the AC power cable, and you could just unplug your remote board too, or take it with the monitor (just wrap the cabling around the monitor frame, use like masking tape or a zip tie if you don't want it dangling around loosely.)

if you wish to move onto the fun part, let me know. cause it's gonna get really exciting. lol

what kind of monitor is this by chance? please tell me it's a Wells...
 
Yeah, it's a wells. I'm just not sure what model. I"m pretty sure it's a 25K7191, if it's the original. Where is the model # on the chassis?

What do you use to discharge the monitor? I made one of those screwdriver/alligator clip things, but I don't trust it that much. I've only discharged a monitor once or twice and it seemed like it had already discharged itself (waited a week) by the time I went to discharge it.

Where can I pick up a cap kit? I've seen them on ebay like this one. Is this the best place to pick one up?

http://cgi.ebay.com/Wells-Gardner-K...emQQptZLH_DefaultDomain_0?hash=item1c0d230033
 
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Yeah, it's a wells. I'm just not sure what model. I"m pretty sure it's a 25K7191, if it's the original. Where is the model # on the chassis?

What do you use to discharge the monitor? I made one of those screwdriver/alligator clip things, but I don't trust it that much. I've only discharged a monitor once or twice and it seemed like it had already discharged itself (waited a week) by the time I went to discharge it.

Where can I pick up a cap kit? I've seen them on ebay like this one. Is this the best place to pick one up?

http://cgi.ebay.com/Wells-Gardner-K...emQQptZLH_DefaultDomain_0?hash=item1c0d230033

the model number placement varies. if you saw something like 25K7191 somewhere on the monitor frame or on or next to the main deflection board, then that's it.

the good news is, those are easy to fix. and you should be extremely glad you don't have a Polo LOL.

your screwdriver/alligator clip method is valid. I actually snipped one of the clips off, stripped the wire a lot, and I think I tinned it with solder and wrapped it around the base of a long Craftsman #2 flathead, and then of course layered that with electrical tape. I don't think you're alone with this particular monitor with it not making a cool *SPARK*, cause my K7171 doesn't do it either.

I actually reach up at the suction cup part of the anode and lift it up on one side just enough to see the anode hooks, then stick the flathead underneath while clipping the other end to the monitor frame. I've been zotted before, but that's because I went to pull a U5000 chassis out and grabbed it from one of the spots that still holds juice when it's off. :001_ssuprised:

everyone here buys from Bob Roberts (http://www.therealbobroberts.net/) but you have to send him a check first before he processes your first order or two. since my family operates an arcade and we order a lot of parts from them anyway, I've gotten my kits from Happ. every monitor I've re-capped with their kits worked fine, except I had one cap on a K7500 pop... I like to think that wasn't my mistake, but there was probably something else wrong with that monitor too.

if I'm not mistaken, since Happ's an authorized NTE dealer, they probably just get all their caps from MCM anyway. that K7500 was the only one I had probs with, I think the kit came with 2 wrong sized caps (that I didn't install).

but......... you won't be ordering from Happ anyway. :)

Bob's excellent, I would've ordered from him, but I haven't set up anything with him yet, like a dufus.

solid advice for you: don't get your electronic components from ebay. I don't trust those people. they overcharge mostly anyway.
 
The only number I can find is the same on the monitor frame and on the tube.

WG 1572795

There was a WG schematic thrown in with the MK2 manual that was in the cab. That's where I got the model #.
 
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yeah, that isn't it then. can you take a picture of it? (I know, this is going to be a challenge :))

most of these shipped with Polos I think, and then they changed to WG 7xxx if I'm not mistaken.

picture quality suffers a little but the WGs are more reliable. I got one in my SFA3 cab that's from Pit Fighter! it's got some minor quirks but otherwise doesn't give me any problems.

the WG K7xxx are all the same except for the K7200, that one's a little different, like it has its own cap kit.
 
I'll take pictures in a couple hours when back at home.

So, I would still think it's a WG because of the number on the frame and tube, not a hantarex.
 
Bob Roberts has a lot of parts. It seems he charges about $7 shipping for the first pound. I may pick up some buttons/switches for the MK2, since they're dirt cheap. I'm already gonna pay the shipping on the cap kit, might as well.
 
mon70.jpg


K7400 perhaps? see if you can find any labels on the top of the monitor frame that say 25K74xx (the xx can vary)
 
my god, I have 2 of those, and I've done a lot of work on one of them. I couldn't see the resolution selector headers. am I correct in understanding that after the U5000 was a flop, the K7400 became the standard res variant, and the K7500 became the medium res variant?

cause the boards are all the same on those. lol

ok, so you're saying the vertical position pot won't adjust the picture, right?
 
my god, I have 2 of those, and I've done a lot of work on one of them. I couldn't see the resolution selector headers. am I correct in understanding that after the U5000 was a flop, the K7400 became the standard res variant, and the K7500 became the medium res variant?

cause the boards are all the same on those. lol

ok, so you're saying the vertical position pot won't adjust the picture, right?



Correct, well, it won't completely. Still have a good inch at the top and bottom that the vertical won't cover.
 
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