Author Topic: K7000 (7197) arc / spark repair (Read 6422 times)

4nic8tor · « **on:** January 26, 2007, 12:39:57 am »

So, I've been reading for days and I just want to make sure I'm doing the right thing before I start buying parts. So I bought a used jamma cabinet and I'm getting ready to convert it. It has a 25" Wells Gardner K7197 carriage with a zenith tube. It worked when I took it but moving around on the ride home the ground that wraps around the carriage of the monitor came disconnected so when I turned it on I heard it arcing. It took me a bit to track it down but I finally realized it was because of the ground wire (I maybe turned it on 4-5 times for a few seconds each time). Once I had reattached the ground wire it stopped arcing but now the video is all distorted and vibrating with horizontal lines.

So I was thinking I probably need a flyback and a cap kit...does that sound right or could it be something else?

4nic8tor · « **Reply #1 on:** January 26, 2007, 12:42:59 am »

I also have a X-Men cab with a RCA TrueType A63ADT10X05 in it but I'm not sure if it works or how bad the burn in is on it. The manufacture date on it is 1990 vs 1993 on the Wells-Gardner. I don't know if it's worth putting in the other cab and trying it or not.

SirPeale · « **Reply #2 on:** January 26, 2007, 01:19:44 am »

Quote from: 4nic8tor on January 26, 2007, 12:39:57 am

...but now the video is all distorted and vibrating with horizontal lines.

So I was thinking I probably need a flyback and a cap kit...does that sound right or could it be something else?

Did you try adjusting the picture with the controls first?

4nic8tor · « **Reply #3 on:** January 26, 2007, 12:46:29 pm »

Ok, that was that problem. I got it up and running and then after about five minutes the monitor just shut off and now it won't turn on. I notice that the ground prong is broken out of the three-pronged power plug. Could that be the problem? Do these monitors have some kind of protection mode? Why would it just go black all of a sudden? It didn't make any noises...it just kind of shut off.

Ken Layton · « **Reply #4 on:** January 26, 2007, 01:15:27 pm »

If the monitor has not had a capkit then that's the first thing I would do.

4nic8tor · « **Reply #5 on:** January 26, 2007, 02:06:21 pm »

Yeah, I just ordered a cap kit and a flyback just in case I need it too. Where do I test for the B+ voltage? The neck does not glow anymore if that helps to diagnose it at all...

grantspain · « **Reply #6 on:** January 26, 2007, 03:16:16 pm »

i think you should check for bad solder joints before buying anything

4nic8tor · « **Reply #7 on:** February 18, 2007, 10:15:36 am »

Ok, I need some help here. Before it just shut off and would not turn back on no matter what I tried. So I cleaned up the board, installed a cap kit, checked and re-did most of the soldering joints, and replaced the HOT and the flyback. Then it turned on perfect. However, just like before it shuts off after like five minutes and will not turn back on. The difference is that now if I unplug it from the wall for like 30 seconds then it will turn on again but it always shuts back off and then you have to unplug it again to get it to come back on. Does anyone have any idea what could cause this? It's obvious that the problem was not with the flyback. I don't want to turn it on anymore for fear it will damage some components and never turn on again like before. Thanks for your help.

Ken Layton · « **Reply #8 on:** February 18, 2007, 10:54:45 am »

Double check the soldering at R89 and R101 resistors. R89 is especially known to have tarnished copper foil under the solder layer. You need to unsolder that resistor to look for evidence of tarnishing.

Also the High Voltage shutdown pot has been known to go bad. The glue they used to seal it sometimes causes problems with that pot.

Diode D18 can sometimes cause problems too.

I'll bet your B+ voltage regulator (mounted on the sidewall) is flaky and needs to be replaced. It has the "STR" prefix on the part number. Wells used 4 different devices (STR 30123, STR 30130, STR 3123, STR 3130) at that location during the production run so it must be replaced with the same device number that's installed now.

4nic8tor · « **Reply #9 on:** February 18, 2007, 11:06:07 am »

Thanks for your super fast reply!! That's exactly the type of information I was looking for. You don't happen to know where this 'high voltage shutdown pot' is located do you? Does it have a number on the board? Could it just be out of adjustment?

4nic8tor · « **Reply #10 on:** February 18, 2007, 11:34:38 am »

Ok, the guy who sold this to me said he had just got it running again and he showed me for a minute before I left. However, from what I can see there is NO isolation transformer in this cab. There is a big huge transformer? on the bottom that has all of the ground wires hooked to it and a gold box which I assume is the power supply but there is no small iso transformer on the sidewall like the one pictured here http://www.therealbobroberts.net/iso.html on Bob Robert's site. Perhaps this is why he only turned it on for a second. So what wires would hook to the isolation transformer? The main power wires (positive & negative) that come from the ps to the main board, correct? Also, what could have been damaged by not having this? And how am I supposed to know which part number to get if there is not one here to compare it to? You said I needed to use the specific one that it came with. Thanks for all your help. I wouldn't know where to start without this board.

Ken Layton · « **Reply #11 on:** February 18, 2007, 11:47:35 am »

Show pictures (small file size please for those of us on dialup like me) of the inside of your cab.

SirPeale · « **Reply #12 on:** February 18, 2007, 11:56:10 am »

Isolation transformers aren't always small.

Sometimes they're also combined as power supplies in older games. I've got a Moon Patrol cabinet that has only one transformer in the bottom. It definitely isolates, but also has other connections for different voltages.

4nic8tor · « **Reply #13 on:** February 18, 2007, 12:15:36 pm »

So, would all of the ground wires in the cab run to the isolation transformer like the one on the bottom of my cab? Because there are two screw holes about 1 1/2" apart on the sidewall of my cab where it looks like there used to be one <edit> Actually, these are the screw holes where the adjustment board for the monitor was mounted.</edit> Also, there is a tag on the black and white power wires on the monitor board which say "WARNING: Isolation transformer must be used!" I can tell that this cab has had some work done on it before so it's possible that they removed it. The big transformer on the bottom looks old as hell and is stamped with the original williams serial number stickers that match all of the other components so I know that it came with the cab. It is where the AC power cord goes and the numbers on the brown paper wrapping around the transformer are:

5610-13326-00REV
682 (9313 stamped)
115/230 Volts
50/60 hz

The power to the monitor comes from this transformer with two purple wires and one ground and they have the matching plug as the wires from the monitor board with no apparent splicing so I don't know where it would have connected in-line. Perhaps it is this large transformer (AC/DC converter???) that needs replaced. I will post pics in just a minute...

SirPeale · « **Reply #14 on:** February 18, 2007, 12:19:06 pm »

That sounds just like my cab, down to the wire colors. It's definitely isolated.

4nic8tor · « **Reply #15 on:** February 18, 2007, 12:27:31 pm »

Ok here are some small pics...

4nic8tor · « **Reply #16 on:** February 18, 2007, 12:41:04 pm »

Quote from: Ken Layton on February 18, 2007, 10:54:45 am

Double check the soldering at R89 and R101 resistors. R89 is especially known to have tarnished copper foil under the solder layer. You need to unsolder that resistor to look for evidence of tarnishing.

Also the High Voltage shutdown pot has been known to go bad. The glue they used to seal it sometimes causes problems with that pot.

Diode D18 can sometimes cause problems too.

I'll bet your B+ voltage regulator (mounted on the sidewall) is flaky and needs to be replaced. It has the "STR" prefix on the part number. Wells used 4 different devices (STR 30123, STR 30130, STR 3123, STR 3130) at that location during the production run so it must be replaced with the same device number that's installed now.

I'm going to try all of this now. I found the high voltage shutdown pot. Is there any specific value that this should be? If you have to replace it do you adjust it while it is on or with a multimeter to a certain value and then glue it? I also wonder if that old ass transformer needs replaced....

Ken Layton · « **Reply #17 on:** February 18, 2007, 01:11:38 pm »

That Midway sticker on the cabinet wall by the monitor tells you what the game was originally.

Your cabinet does have an isolation transformer....sort of. I mentioned this in the thread about the Nieman monitors I installed at the Blue Fox Drive-in theater. Midway in their infinite stupidity wired virtually all the 120 volt AC operated things in the cabinet on the SECONDARY side of that isolation transformer (a big no-no). As these cabinets were originally shipped with either a Wells-Gardner U-2000, U-5000, or Hantarex "Polo" monitor it didn't matter as these models had a built-in switching power supply which did not need isolation. However since you have a k7000 series monitor in there now (which DOES need isolation) it definitely matters.

Midway should have wired the gameboard swiching power supply to the PRIMARY of the isolation transformer. How the Underwriter's Laboratories inspectors let the $eriou$ wiring mi$take get by i$ beyond me.

4nic8tor · « **Reply #18 on:** February 18, 2007, 01:19:42 pm »

Sweet, I did read that thread about the Nieman monitors you installed but I must have missed that. I will re-read it and correct the wiring. Also, (sorry for so many questions) there are some problems with r101. The trace seems to be pulled from the board, but it IS still making contact when I test from adjacent points. However, when I measure the resistance on the actual leads right at the resistor (or otherwise) it starts at 5K ohm and then slowwwwly rises to about 6K where it pretty much stops. It's supposed to be 6.8K. I've never seen a resistor change values all slow like that so I assume that means it is bad? Also, when the layer beneath the solder is tarnished do you usually jump it to the next closest point with some excess solder or scrape away the protective layer on the trace adjacent to the existing point and spread it out to there? Probably all the same, huh? Thanks.

SirPeale · « **Reply #19 on:** February 18, 2007, 01:22:21 pm »

You'll have to check the resistor out of circuit.

4nic8tor · « **Reply #20 on:** February 18, 2007, 01:25:26 pm »

Thanks Peale, that worked. The resistor is good. Looks like the cab started out NBA Basketball...

4nic8tor · « **Reply #21 on:** February 18, 2007, 01:39:45 pm »

I've been doing electronics, consoles, and stuff like this for a long time but for some reason these game cabs are making me feel like a total noob, LOL.

I don't know which side is the primary and secondary. The monitor is powered from purple wires. One purple, one purple/yellow. Do I only need to rewire the wires from the monitor and do I just splice them with some on the right instead of the left? Do I need to move both purple wires or just one? I re-read this thread http://forum.arcadecontrols.com/index.php?topic=61470.0 and I still don't see mention of these transformers....maybe I'm a blind noob too.

I have no idea what I'm doing here....

Kevin Mullins · « **Reply #22 on:** February 18, 2007, 01:52:19 pm »

Follow the AC cord that plugs into the wall back to the transformer....that's your PRIMARY side.

Power for the switching power supply should come from that side as well. (I believe that is what Ken is trying to explain)

The monitor should be wired to the SECONDARY side. This would then keep it "isolated" from the rest of the AC components. (switching power supply, game pcb, etc)

4nic8tor · « **Reply #23 on:** February 18, 2007, 02:25:44 pm »

Ok, I have never worked with transformers before so please excuse my ignorance. The ac goes into the emi filter then out to the switch on top of the cab. Then it goes to the side of the transformer with the numbers on the brown paper opposite the side with all the purple wires. The switching power supply's wires seem to run up to the switch as well. Am I supposed to tear the brown paper off the transformer then? I can't see what is happening with the wires once they go into the paper....

Ken Layton · « **Reply #24 on:** February 18, 2007, 08:20:41 pm »

I know I just talked about that Midway transformer in another thread about two weeks ago....I just don't remember what the thread title was or if it was on this forum.

Anyway, the purple wires stay connected as they are now since that is the correct side of the transformer going to the monitor. You don't tear the wrapper off the transformer...ever.

I had downloaded a copy of the transformer module wiring from a Mortal Kombat 2 manual I think, but I no longer have that diagram. I took it up to the Blue Fox Drive-in theater and left it inside the Ultracade machine. It's a conversion cabinet of a Blitz game that uses the same transformer and their (the theater's) cabinet had no wiring diagrams at all so I left the diagram in the machine figuring If I ever needed one again I could go download & print another one.

4nic8tor · « **Reply #25 on:** February 20, 2007, 01:13:28 pm »

Ok, I am now checking diodes D18 and D12. D12 is a 1N5240B and the data sheet says it is a 10v diode. So what should the reading on my multimeter be? It's reading .680v and the D18 (apparently a DG3 sinterglass diode??) is reading .452v. I haven't really tested diodes before so hopefully I'm doing it correctly. Just set it to diode and negative to the banded side positive to the other side, right? These readings don't seem like anything I'm seeing in the data sheets so are they both bad?

4nic8tor · « **Reply #26 on:** February 20, 2007, 01:57:18 pm »

Ok, I have confirmed that neither diode is shorted or 'opened up' but apparently I have to build a circuit with slightly more power than the diode is rated for to test it. Is this worth it? Do they generally short or open up when they fail or does their value change?

SirPeale · « **Reply #27 on:** February 20, 2007, 07:15:09 pm »

When you check a diode, you should check it out of circuit. You don't have to completely remove it. Just unsolder one leg and lift it up slightly.

Use the diode setting on your meter. Black on the banded side, red on the other. You'll likely get a reading somewhere between .500 and .800. These are approximate measurements. Then swap the leads to the other ends. If you get any reading at all, it's a bad diode.

4nic8tor · « **Reply #28 on:** February 20, 2007, 09:47:42 pm »

Got it...it's fixed!

Thanks for all of your help guys. It's not the greatest monitor but it will do the trick for a year or so until I can buy a nice brand new one. I believe the flyback was the original problem and then I had a hairline piece of solder splatter that may have been shorting to a trace. I also re-did the soldering on the recommended resistors and no more shutdown! I was going to try the voltage regulator and then I think I was done with this monitor so I'm glad it's working now.

4nic8tor · « **Reply #29 on:** March 02, 2007, 07:37:24 pm »

Ok, I'm done. This thing is frustrating. It worked for like a week and then went out again. So I replaced the voltage regulator and it's still dead. I just can't see putting any more money into this thing. I guess I'm just going to buy a new monitor for it when I get my tax returns. So does anyone have any recommendations for a good 25" arcade monitor for use with an ArcadeVGA card? It sounds like these Nieman monitors are pretty good. What are my other options? I heard something about refurbished monitors from WG. What are other good options and price ranges if anyone knows?

ACJ · « **Reply #30 on:** March 12, 2007, 01:47:04 pm »

I recently came across the transformer assembly mentioned (part number 5610-13326-00). In my search for info I think I've found the schematic that Ken mentioned:

http://www.arcadedocs.com/vidmanuals/M/mk2-wiring.pdf

Looks like it was used in Mortal Kombat II (1993). In the power wiring diagram you'll see the part number of the transformer and indeed all but the coin door lights are connected to the secondary. Apparently it can handle the load as the rating on the secondary is shown as 2 amperes. Ideally, the transformer one uses should be capable of supplying the needs of any future monitor one plans to use.

I expected the open circuit voltage to be a little bit high with 120 Vac input, but was surprised to measure 130 Vac. This was undesirable. I checked the jumpers and reset them (per Bob Robert's tip) and now the voltage reads 114 Vac, quite a bit better.

I welcome any comments, corrections, etc.


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